ALBERT

Description: This research aimed to address health and food security challenges affecting Los Angeles and beyond in our own backyard. One possible way to combat these challenges is through biotechnology. The purpose of this research was to characterize the arable soils at Los Angeles Pierce College and their potential uses. The methods employed were collection of soil physical and chemical properties, cultivation of soil microorganisms, and 16S rDNA sequencing with a citizen science platform. Statistical analysis in R revealed associations between field conditions and life in the soil. The testing of plant-based antimicrobial agents on antibiotic-resistant bacteria revealed that plant oils could be more efficacious for control than common antibiotics. We found evidence of plant growth-promoting, antibiotic-producing, and bioremediating bacteria in different fields with distinct microclimates based on the 16S rDNA taxonomy results and inferred functional profiles. The major findings included an abundance of Streptomyces, Bacillus, Methylobacteria, and others with desirable functions. Numerous Streptomyces isolates cultivated on selective media demonstrated the ability to reduce nitrate. These results will empower future trials and product development by identifying target soil microorganisms and the most viable fields.

Description: Soil conservation practices such as cover crops can improve crop production, soil quality, and water quality. Cover crops can also influence soil microbial growth and activity. Cover cropped and manured soils can potentially store and transmit fecal bacteria (e.g., E. coli) to surface water if runoff and subsurface seepage occur. While many studies have shown the soil health benefits of cover crops, fewer studies have evaluated the extent to which cover crops influence the abundance of potential waste-borne pathogens. A two-year study (2015–2017) was conducted on a limited-resource farm in Logan County, Kentucky, USA, to quantify the abundance of the fecal indicator Escherichia coli (E. coli) bacteria (as a proxy for fecal coliforms) in treatments with and without cover crops or composted poultry litter. The cover crop consisted of a cereal rye (Secale cereale L.), Austrian winter pea (Pisum sativum L.), and crimson clover (Trifolium incarnatum L.) mix. Summer crops consisted of a no-till maize (Zea mays L.)—soybean (Glycine max L.) rotation. Soil samples were taken before and after each summer crop season and assessed to detect and enumerate E. coli. At the end of the study period, no significant treatment differences in the E. coli abundance in soil were detected (ca. 104 CFU·g−1) (). However, season/time was a significant factor (). We conclude that the background E. coli already present in soil was sufficiently high, inhibiting the detection of the influence of added composted litter. These indigenous E. coli were unaffected by cover crop and nutrient management but did fluctuate on a seasonal basis.

Description: As an effect of intensive agricultural development of the steppes of the northern Black Sea coast, the finds of postantique agricultural landscapes that preserve relic elements of ancient land-use infrastructure are extremely rare. To these belongs the uniquely preserved ancient Greek land division system on the Tarkhankut Peninsula (north-western Crimea), which was studied using the methods of soil science and biomorphic analysis. This paper explores ancient land-use practices in order to reconstruct the original parameters of the land division system, as well as agricultural techniques employed. For postantique agricultural landscapes, an integrated geoarchaeological approach that includes GIS and remote sensing methodologies, in-field study of microrelief and soil registrograms, pedochronological dating technique, and physicochemical, geochemical, and biomorphic soil analyses has been developed and tested. The soil-geomorphological reconstruction shows that the Hellenistic land division system included a 4.5–4.9 m wide strip of land bordered by a 4.1–4.7 m wide (at the base) and c. 0.2 m high wall and a c. 2 m wide and over 15 cm deep trench, which controlled surface runoff and erosion. Ancient agricultural practices of slope farming resembled the modern ones. Surface runoff and soil erosion were controlled by dividing the catchment area into narrow plots, the borders of which on arable land were marked by simple earthen structures (low walls with shallow trenches). The biomorphic analysis of soil sampled atop these structures indicates that in ancient times, these earthen walls were not cultivated. The study of conservative properties preserved in pedomemory of postagrogenic soils provided valuable evidence of agricultural techniques used in the palaeogeographic conditions of the 4th and 3rd centuries BC.

Description: Land degradation is a global negative environmental process that causes the decline in the productivity of land resources’ capacity to perform their functions. Though soil and water conservation (SWC) technologies have been adopted in Geshy subcatchment, their effects on soil quality were limitedly studied. The study was conducted to evaluate the effects SWC measures on soil quality indicators in Geshy subcatchment, Gojeb River Catchment, Ethiopia. A total of 54 soil samples (two treatments–farmlands with and without SWC measures  three slope classes  three terrace positions  three replications) were collected at a depth of 20 cm. Statistical differences in soil quality indicators were analyzed using multivariate analysis of variance (ANOVA) following the general linear model procedure of SPSS Version 20.0 for Windows. Means that exhibited significant differences were compared using Tukey’s honest significance difference at 5% probability level. The studied soils are characterized by low bulk density, slightly acidic with clay and clay loam texture. The results revealed that farmlands with SWC measures had significantly improved soil physical (silt and clay fractions, and volumetric soil water content (VSWC)) and chemical (pH, SOC, TN, C : N ratio, and Av. phosphorus) quality indicators as compared with farmlands without SWC measures. The significantly higher VSWC, clay, SOC, TN, C : N ratio, and Av. P at the bottom slope classes and terrace positions could be attributed to the erosion reduction and deposition effects of SWC measures. Generally, the status of the studied soils is low in SOC contents, TN, C : N ratio, and Av. P (deficient). Thus, integral use of both physical and biological SWC options and agronomic interventions would have paramount importance in improving soil quality for better agricultural production and productivity.

Description: Decomposition is a key flux of terrestrial carbon to the atmosphere. Therefore, gaining a better understanding of how plant litter decomposes in soil, and what governs this process, is vital for global climate models. The Tea Bag Index (TBI) was introduced by Keuskamp et al. (2013) as a novel method for measuring litter decomposition rate and stabilisation. The TBI uses two types of tea bags representing fast (green tea) and slow (rooibos tea) decomposition substrates as standardised litter bags. To date, the TBI method has been used in over 2000 locations across the globe. However, before now, there has been no information on how the composition of the tea leaves change during incubation. These data are crucial in determining the validity of the use of the TBI method globally, to ensure the tea leaves decompose in a way that is representative of so-called “native” litters. To provide chemical underpinning of the TBI method, a laboratory incubation of the tea bags was conducted with destructive sampling at 0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, and 91 d. The incubated tea was analysed for total C and N. In addition, C was characterised as alkyl, O-alkyl, aromatic, or carbonyl C using solid-state 13C nuclear magnetic resonance spectroscopy with cross-polarization and magic angle spinning (CPMAS NMR). The results suggest that changes in carbon in both tea types are comparable to other litter studies, with a net decrease in total C and relative proportion of O-alkyl C fraction, which contains carbohydrates and cellulose. We conclude that the decomposition of tea leaves in the bags used in the TBI is representative of other litters.

Description: Soil loss triggered by water erosion constitutes a major issue that causes several environmental and socioeconomic concerns. The Moroccan Western High Atlas is the most vulnerable area in the High Atlas Mountains, due to the existence of different forms of landslides, and evidences of erosion are widely observed. This study aims at estimating and quantifying the amount of soil loss as well as highlighting potential areas to erosion risk, using the Revised Universal Soil Loss Equation (RUSLE) combined with GIS and remote sensing. The RUSLE model provides a possibility of computing erosion susceptibility for each pixel on the basis of the controlling factors which are rainfall aggressivity, topography, vegetation cover, soil erodibility, and support practices. In this study, results show that the erosion rate varies between 0 and 227.67 t/ha/year, with an average annual soil loss of 40.38 t/ha/year, and the Beni Mohand River basin is subject to very high rates of erosion which can be irreversible since it exceeds the tolerable standard rate which is 1 t/ha/year. These findings will provide land use planners baseline for land use and risk management and will provide data within the Moroccan Western High Atlas Mountains.

Description: Land degradation is a global negative environmental process that causes the decline in the productivity of land resources’ capacity to perform their functions. Though soil and water conservation (SWC) technologies have been adopted in Geshy subcatchment, their effects on soil quality were limitedly studied. The study was conducted to evaluate the effects SWC measures on soil quality indicators in Geshy subcatchment, Gojeb River Catchment, Ethiopia. A total of 54 soil samples (two treatments–farmlands with and without SWC measures  three slope classes  three terrace positions  three replications) were collected at a depth of 20 cm. Statistical differences in soil quality indicators were analyzed using multivariate analysis of variance (ANOVA) following the general linear model procedure of SPSS Version 20.0 for Windows. Means that exhibited significant differences were compared using Tukey’s honest significance difference at 5% probability level. The studied soils are characterized by low bulk density, slightly acidic with clay and clay loam texture. The results revealed that farmlands with SWC measures had significantly improved soil physical (silt and clay fractions, and volumetric soil water content (VSWC)) and chemical (pH, SOC, TN, C : N ratio, and Av. phosphorus) quality indicators as compared with farmlands without SWC measures. The significantly higher VSWC, clay, SOC, TN, C : N ratio, and Av. P at the bottom slope classes and terrace positions could be attributed to the erosion reduction and deposition effects of SWC measures. Generally, the status of the studied soils is low in SOC contents, TN, C : N ratio, and Av. P (deficient). Thus, integral use of both physical and biological SWC options and agronomic interventions would have paramount importance in improving soil quality for better agricultural production and productivity.

Description: Decomposition is a key flux of terrestrial carbon to the atmosphere. Therefore, gaining a better understanding of how plant litter decomposes in soil, and what governs this process, is vital for global climate models. The Tea Bag Index (TBI) was introduced by Keuskamp et al. (2013) as a novel method for measuring litter decomposition rate and stabilisation. The TBI uses two types of tea bags representing fast (green tea) and slow (rooibos tea) decomposition substrates as standardised litter bags. To date, the TBI method has been used in over 2000 locations across the globe. However, before now, there has been no information on how the composition of the tea leaves change during incubation. These data are crucial in determining the validity of the use of the TBI method globally, to ensure the tea leaves decompose in a way that is representative of so-called “native” litters. To provide chemical underpinning of the TBI method, a laboratory incubation of the tea bags was conducted with destructive sampling at 0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, and 91 d. The incubated tea was analysed for total C and N. In addition, C was characterised as alkyl, O-alkyl, aromatic, or carbonyl C using solid-state 13C nuclear magnetic resonance spectroscopy with cross-polarization and magic angle spinning (CPMAS NMR). The results suggest that changes in carbon in both tea types are comparable to other litter studies, with a net decrease in total C and relative proportion of O-alkyl C fraction, which contains carbohydrates and cellulose. We conclude that the decomposition of tea leaves in the bags used in the TBI is representative of other litters.

Description: Luong Son is a district to the east gateway of Hoa Binh province, adjacent to Hanoi the capital and the northwest of Vietnam. Against the background of the rapidly expanding natural resources exploitation, a lack of experience in the general management of resources is obvious. The problem of serious environmental pollution occurs due to the increase of mining activities. This is especially true in mining areas located near fast-growing urban areas. In particular, after the end of the exploitation and mine closure, there is a need to improve and recover the environmental conditions in order to protect untapped mineral reserves and to keep the exploitation site in a sustainable status. This includes questions of environmental safety and soil recovery within the affected areas. This article deals with 2 types of land improvement and restoration in Luong Son district: (1) designing a method for land improvement by afforestation and (2) designing a method for land improvement by planting fruit trees and short-term crops.

Description: Soil is spatially heterogeneous and needs site-specific management. However, soil nutrient information at larger scale in most cases is lacking. Consequently, fertilizer advisory services become dependent upon blanket recommendation approach. Subsequently, it affects yield and profitability. This study is aimed at explaining soil fertility heterogeneity in Wolaita zone, Southern Ethiopia. About 789 soil samples were collected to evaluate soil physical (color, particle size, and bulk density) and chemical properties (pH, OC, N, P, K, Ca, Mg, B, Cu, Fe, Mn, Zn, PBS, and CEC). The laser diffraction method for soil particles and mid-infrared diffused reflectance (MIR) spectral analysis for OC, TN, and CEC determination were employed. Mehlich-III extraction and inductively coupled plasma (ICP) spectrometer measurement were used for the remaining elements. The result based on principal component analysis showed that 52% of the total variations were explained by exchangeable bases, CEC, pH, available P, Cu, B, and particle sizes. Clay texture and acidic soil reaction are dominant. Soil parameters with the following ranges were found at low status: soil OC (0.2–6.9%), total N (0.01–0.7%), available P (0.1–238 mg/kg), S (4–30 mg/kg), B (0.01–6.9 mg/kg), and Cu (0.01–5.0 mg/kg). Besides, low levels of exchangeable Ca, Mg, and K (Mg-induced K deficiency) on 22, 34, and 54% soil samples, respectively, were recorded. The soil contained sufficient Fe, Zn, and Mn. In conclusion, the study aids in developing practical decision for optimum soil management interventions and overcomes lower productivity occurring due to fertilizer use that is not tailored to the local conditions. Overall, continuous cropping, low return of crop residues, and low and/or no fertilizer application might have caused the low status of N, P, K, S, B, and Cu. Therefore, application of inorganic fertilizers specific to the site, lime in acidic soils, and organic fertilizers are recommended to restore the soil fertility and improve crop productivity.

Description: Conservation tillage has many advantages in crop production and weed control management. N-residue of hairy vetch as a green manure cover crop through tillage and no-tillage practices may increase inorganic-N level in soils and contribute to sustainable agriculture. Prior to corn cultivation, hairy vetch was cut after growing in the pots for 103 days. Six treated soils were prepared for no-tillage treatments (SRN, RN, and CN) and for tillage treatments (SRT, RT, and CT), where the soils were treated by shoot and root of hairy vetch residues, only root residues, and without application of hairy vetch as a control, respectively. Seeds of corn (Zea mays L.) were sown and grown for 56 days after sowing. The shoot and root biomasses of corn under no-tillage were higher than those of tillage. Furthermore, the shoot biomass of corn in both SRN and SRT were higher than that in other treatments. The root biomass of corn was higher in upper layers (0–5 cm depth) and deeper layers (〉10 cm depth) than in middle layers (5–10 cm depth) of soils. In the upper layer, the NH4-N contents of no-tillage were higher at 9 and 23 DAT than those of tillage. The NH4-N content of the soils for no-tillage in the middle layer and the deeper layer was lower than that of the CT treatment. The NO3-N content of no-tillage in the middle and deeper layers was lower than that of CT at 23 and 65 DAT. N-uptake of corn in both no-tillage and tillage treatments with hairy vetch addition was higher than that of the control.

Description: Rapid land use changes have been observed in recent years in central Ethiopia. The shift from natural ecosystem to artificial ecosystem is the main direction of change. Therefore, this study was initiated to assess the effects of land use types on selected soil properties in Meja watershed, central highlands of Ethiopia. The randomized complete block design, including three adjacent land use types as treatments with three replications and two soil depths (0–15 and 15–30 cm), was applied in this study. There were significant differences in some soil properties among the three land use types. Lower soil pH and electric conductivity were observed in cultivated land soils than Eucalyptus woodlots soils. This has indicated the worsening soil conditions due to the shift from Eucalyptus woodlots to cultivated land. Less decomposition rate of the Eucalyptus leaves and debris collection for fuel could result in lowest soil organic carbon at the upper layer of Eucalyptus woodlot soils. However, the highest soil organic carbon at the lower layer was observed in Eucalyptus woodlot soils. The presence of highest soil potassium, cation exchange capacity, and exchangeable potassium in cultivated land soil was related to application of artificial fertilizers. Grassland soils have highest exchangeable sodium at the lower layer while highest soil carbon and sum cations at the upper layer, which can be related to the grass root biomass return and less surface runoff on grassland. There was the highest exchangeable sodium percentage on Eucalyptus woodlot soils at the upper layer; it can be due to the less surface nutrient movement and growth characteristics of the tree. The soils in cultivated land was shifted to more acidic and less electric conductivity.This shift can lead to soil quality deterioration that affects the productivity of the soils in the future.Nutrient leaching, application of artificial fertilizer, soil erosion, and continuous farming have affected the soil properties in cultivated land. The presence of highest exchangeable sodium percentage and lowest sum of cations at the upper layer of soil in Eucalyptus woodlot should be noted for management and decision makers. The previous negative speculations on Eucalyptus woodlots which can be related with the soil texture, soil moisture, bulk density, total nitrogen, exchangeable magnesium, calcium, and available sulfur should be avoided because there were no significant differences observed among the three land use types in the study area. The study recommends further studies on the effects of Eucalyptus on soil properties by comparing among different ages and species of Eucalyptus. Finally, planting of Eucalyptus on central highlands of Ethiopia should be supported by land use management decision.

Description: Structural characteristics of local saline-alkali soil in the Yellow River Delta were studied by microscopic test methods of liquid nitrogen vacuum freeze-drying machine, fully automatic mercury intrusion porosimetry, X-ray diffractometer, and high- and low-vacuum scanning electron microscope. Permeability of the saline-alkali soil belongs to two grades of micropermeable water and extremely micropermeable water. Average volume ratio of pores with diameters no more than 2 μm is 86.25%; therefore, the saline-alkali soil may mainly consist of micropores and ultramicropores. Most void ratios of the soil are not beyond 0.5, and its dry densities are all greater than 1.6 g/cm3. Because average proportion of the clay minerals is only 12.24%, they are obviously not the main reason for poor permeability of the local saline-alkali soil. Based on the structural characteristics of compact structure and slightly developed fracture, mechanisms of surface runoff, and water-salt migration of the local saline-alkali soil, a salt-discharging engineering model mainly with surface runoff was established considering auxiliary infiltration and without interflow. Salt content distribution of the local saline-alkali soil is studied experimentally, by which relationship between salt content and conductivity has been fitted as y = 2.74x. The relationships between depth and salt content in the saline-alkali soil region present that the depth of salt-discharging engineering as open ditch should be beyond 60 cm. From the relationships between precipitation and salt content, the effectiveness of engineering measure shown in the salt-discharging model has been verified immediately or indirectly, and the engineering salt-discharging model may be suitable for managing saline-alkali soil in the Yellow River Delta.

Description: The remediation of opencast bauxite mines in the natural forests of Indonesia is difficult. We have investigated and contrasted the chemical characteristics of soils from natural forests and mining sites and their effects on plant growth. The soil pH, total carbon (C), nitrogen (N) and available phosphorus (P) concentrations, cation exchange capacity, C/N ratio, and exchangeable K, Na, Mg, Ca, Fe, and Ni concentrations were determined. Falcataria moluccana and Albizia saman were then grown in these soils for 15 weeks, and their shoot heights, shoot dry weights, and root dry weights determined. The post bauxite mining soils’ N, C, and available P concentrations and exchangeable Ca, Mg, and Na concentrations decreased by 75, 75.7, 15.7, 92, 100, and 52%, respectively, in comparison with the natural forest soils. The shoot and root dry weights of F. moluccana when grown in the post bauxite mining soils were also lower than those from the natural forest soils. However, there was no difference in the shoot and root dry weights of A. saman when grown in the two soil types. The results suggest that opencast mining decreases the soil fertility, which in turn inhibits the initial growth of tree seedlings, and reduces the carbon stock in the land.

Description: Soil organic carbon constitutes an important indicator of soil fertility. The purpose of this study was to predict soil organic carbon content in the mountainous terrain of eastern Lesotho, southern Africa, which is an area of high endemic biodiversity as well as an area extensively used for small-scale agriculture. An integrated field and laboratory approach was undertaken, through measurements of reflectance spectra of soil using an Analytical Spectral Device (ASD) FieldSpec® 4 optical sensor. Soil spectra were collected on the land surface under field conditions and then on soil in the laboratory, in order to assess the accuracy of field spectroscopy-based models. The predictive performance of two different statistical models (random forest and partial least square regression) was compared. Results show that random forest regression can most accurately predict the soil organic carbon contents on an independent dataset using the field spectroscopy data. In contrast, the partial least square regression model overfits the calibration dataset. Important wavelengths to predict soil organic contents were localised around the visible range (400–700 nm). This study shows that soil organic carbon can be most accurately estimated using derivative field spectroscopy measurements and random forest regression.

Description: Phytoextraction is an effective and environment-friendly approach for remediation of soil polluted with toxic metals. Portulaca oleracea is a potential hyperaccumulator of Cr(VI) from polluted soil. In this study, the effect of soil organic content, pH, and sulphate concentration on phytoextraction of Cr(VI) using Portulaca oleracea was investigated. Seedlings of Portulaca oleracea were grown in soils with (i) three organic content compositions, (ii) six levels of pH, and (iii) six concentrations of sulphate salts; all were irrigated with Cr(VI) solutions at 200 ppm concentration. Chromium concentration in different tissues of plants was monitored under the variant conditions. Results indicated that the uptake of Cr(VI) by Portulaca oleracea is favoured at (i) low organic content soil (0.42%), (ii) slightly alkaline pH range (∼8), and (iii) with sulphate concentration in the range of 300–600 ppm.

Description: The use of silver in various spheres of life and production leads to an increase in environmental pollution, including soil. At the same time, the environmental consequences of silver pollution of soils have been studied to a much lesser extent than those of other heavy metals. The aim of this study is to estimate silver ecotoxicity using the soil state biological indicators. We studied soils that are significantly different in resistance to heavy metal pollution: ordinary chernozem (Haplic Chernozems, Loamic), sierosands (Haplic Arenosols, Eutric), and brown forest acidic soil (Haplic Cambisols, Eutric). Contamination was simulated in the laboratory. Silver was introduced into the soil in the form of nitrate in doses of 1, 10, and 100 mg/kg. Changes in biological parameters were assessed 10, 30, and 90 days after contamination. Silver pollution of soils in most cases leads to deterioration of their biological properties: the total number of bacteria, the abundance of bacteria of the genus Azotobacter, the activity of enzymes (catalase and dehydrogenases), and the phytotoxicity indicators decrease. The degree of reduction in biological properties depends on the silver concentration in the soil and the period from the contamination moment. In most cases, there is a direct relationship between the silver concentration and the degree of deterioration of the studied soil properties. The silver toxic effect was most pronounced on the 30th day after contamination. In terms of their resistance to silver pollution, the studied soils are in the following order: ordinary chernozem 〉 sierosands ≥ brown forest soil. The light granulometric composition of sierosands and the acidic reaction of the environment of brown forest soils, as well as the low content of organic matter, contribute to high mobility and, consequently, high ecotoxicity of silver in these soils. The regional maximum permissible concentration (rMPC) of silver in ordinary chernozem (Haplic Chernozems, Loamic) is 4.4 mg/kg, in sierosands (Haplic Arenosols, Eutric) 0.9 mg/kg, and in brown forest soils (Haplic Cambisols, Eutric) 0.8 mg/kg.

Description: The objectives of this study were to investigate effects of land use on accumulation of soil organic matter (SOM) in the soil profile (0–100 cm) and to determine pattern of SOM stock distribution in soil profiles. Soil samples were collected from five soil depths at 20 cm intervals from 0 to 100 cm under four adjacent land uses including forest, cassava, sugarcane, and paddy lands located in six districts of Maha Sarakham province in the Northeast of Thailand. When considering SOM stock among different land uses in all locations, forest soils had significantly higher total SOM stocks in 0–100 cm (193 Mg·C·ha−1) than those in cassava, sugarcane, and paddy soils in all locations. Leaf litter and remaining rice stover on soil surfaces resulted in a higher amount of SOM stocks in topsoil (0–20 cm) than subsoil (20–100 cm) in some forest and paddy land uses. General pattern of SOM stock distribution in soil profiles was such that the SOM stock declined with soil depth. Although SOM stocks decreased with depth, the subsoil stock contributes to longer term storage of C than topsoils as they are more stabilized through adsorption onto clay fraction in finer textured subsoil than those of the topsoils. Agricultural practices, notably applications of organic materials, such as cattle manure, could increase subsoil SOM stock as found in some agricultural land uses (cassava and sugarcane) in some location in our study. Upland agricultural land uses, notably cassava, caused high rate of soil degradation. To restore soil fertility of these agricultural lands, appropriate agronomic practices including application of organic soil amendments, return of crop residues, and reduction of soil disturbance to increase and maintain SOM stock, should be practiced.

Description: Landfills are major sources of environmental pollution. This study evaluated heavy metal concentrations in soils and plants around the closed Lumberstewart landfill in Bulawayo, Zimbabwe, to determine the pollution potential of a closed landfill and the risks they present to plants growing in this environment and surrounding communities. Soil samples were collected at depths of 0–30 cm, 30–60 cm, and 60–90 cm around the landfill and at a control site and characterized for various properties and concentrations of Cd, Cu, Cr, Fe, Ni, and Zn. Samples of Datura stramonium, collected from the same sites where soil samples were collected, were also analyzed for the same heavy metals. The soils were sandy, mostly acidic (5.01  Ni 〉 Cd with samples from around the landfill having higher concentrations than samples from the control site. Soil heavy metal enrichment was highest at a depth of 30–60 cm. Pollution load index (PLI) values indicated that all sites around the landfill were polluted (PLI 〉 1). Heavy metal transfer coefficient in Datura stramonium ranged between 0.0 and 209 with

Description: Active land disturbance of soil and environments appears even in remote landscapes of tundra and forest tundra. Wildfires become a frequent factor of soil degradation and intensification of permafrost degradation, also affecting the global balance of carbon, especially content and distribution of polycyclic aromatic compounds. Mature unaffected by fire sandy-textured podzols soils were investigated in comparison with the same soil strongly affected by surface fire in the end of August 2016 in surroundings of the Pangody settlement, Nadym district, Yamal region. Data obtained showed an intensive morphological transformation of the topsoil layers, decreasing total organic matter and apparently increasing the humus enrichment by nitrogen. Wildfires also result in complete transformation of the fractional composition of the polycyclic aromatic compounds. The sum of PAHs increases intensively as well as benzo(a)pyrene content in soils. Therefore, soils of the cryolithozone become more faced to the wildfires during the last decades. Even one-time fire effect results in serious transformation of soil geochemical state.

Description: Recent research findings imply that the slope aspect has a great impact on soil genesis and soil microclimate. The microclimate has a significant effect on the soil geobiochemical processes taking place in the soil. However, the slope aspect impact on soil properties has not been yet studied well in Ethiopia, particularly in the northern highlands. This research was initiated to link selected soil physicochemical properties with slope aspects under different land use practices. The research was conducted in Gumara-Maksegnit watershed located at the upper Lake Tana basin, Ethiopia. Four slope aspects, eastward (Ew), northward (Nw), southward (Sw), and westward (Ww), and three land use types at each slope aspect, cropland (Cl), forest land (Fl), and grazing land (Gl), were considered. In total, 36 undisturbed soil samples for bulk density and 36 disturbed soil samples for selected soil properties were collected. Soil particle size (texture), bulk density, electrical conductivity (EC), soil pH, available phosphorus (av. P), available potassium (av. K), total nitrogen (TN), and soil organic carbon (SOC) were analyzed. The resulting analyses showed no significant variation (p

Description: Despite the fact that mineral fertilizers are widely considered as a major option for addressing the crisis of nutrient depletion, their use among smallholder farmers is not adequate due to an escalating cost. Alternatively, nutrient-rich organic sources that are easily available to farmers are not widely promoted. Thus, this study was carried out in the research field of Wolaita Sodo University, Southern Ethiopia, to evaluate the effects of locally available organic nutrient sources and nitrogen (N) phosphorus (P) sulfur (S) fertilizer (19N-46P2O5-7S) on the productivity and economic performance of common bean. The organic materials used were Croton (Croton macrostachyus) and Erythrina (Erythrina brucei) at 2 : 1 ratio, respectively. The experiment was laid out in a randomized complete block design with three replications. Treatments for organic fertilizer (OF) were 0, 2.5, and 5 t·ha−1 and for NPS fertilizer were 0, 50, 100, and 150 kg·ha−1. Chemical composition analysis of organic materials showed high nutrient content where the amount varied from 4.7%–5.2% N, 11.07–18.6 mg/kg P, and 2.12%–3.07% K. Results on agronomic parameters revealed that the leaf area index, grain weight, number of pods per plant, dry matter per plant, and grain yield of haricot bean were significantly affected by both main and combined effects of NPS and OF fertilizers. The grain yield under integrated application of 150 kg NPS/ha and 2.5 t·OF/ha (4.16 t/ha) was significantly higher than that obtained from unfertilized crop (1.01 t/ha) by 312%. Additionally, it resulted in 34%, 31%, and 79% yield increment over the blanket dose (100 kg·NPS·ha−1), 2.5 t/ha and 5 t/ha, respectively. It was also noted that resource-poor farmers, compared to unfertilized crop, can get grain yield superior by 130% and 214% using sole OF at 2.5 and 5 t·ha−1, respectively. Furthermore, the highest economic benefit (27, 179.5EtB) was recorded from 150 kg NPS/ha + 2.5 t·OF/ha. The finding suggested that locally available organic materials of plant origin alone/integrated with NPS fertilizer are helpful for increased yield of haricot bean.

Description: Different land use systems can have different soil properties. It is important to study the soil properties for wise use and sustainable management of land resources. This article reports the findings of a research conducted in Makwanpur district of Nepal, to determine and compare the selected physicochemical and hydrological properties of soil in forest, rainfed agriculture land, and grassland. These forest, agriculture land, and grassland represent tropical land use systems. Soil samples were collected from 0 to 30 cm depths of soil profile from nine randomly distributed pits dug in forest, grassland, and rainfed agriculture land in 2019. Soil samples were analyzed in the laboratory to determine the soil properties using standard methods. Bulk density, porosity, moisture content and infiltration, pH, total nitrogen, available potassium, and available phosphorus were quantified from the soils samples. It was found that the highest BD was found in the grassland (1.29 g/cm³) followed by the forest (1.23 g/cm³) and rainfed agriculture land (1.18 g/cm³). The highest porosity was found in rainfed agriculture land (55.50%) followed by the forest (53.74%) and grassland (51.63%). The highest MC was found in the grassland (26.94%) followed by the forest (10.17%) and rainfed agriculture land (9.92%). The mean cumulative infiltration amount was highest in the rainfed agriculture land (39.27 cm) followed by the forest (33.47 cm) and grassland (8.4 cm). The highest soil pH was found in the grassland (7.91) and the lowest pH (5.70) in the forest. The highest level of total nitrogen was found in rainfed agriculture land (0.121%), followed by the forest (0.106%) and grassland (0.096%). The highest level of available phosphorous was found in rainfed agriculture land (84.94 ppm), followed by the forest (67.76 ppm) and grassland (6.69). The highest level of available potassium was found in rainfed agriculture land (154.24 ppm), followed by the forest (84.49 ppm) and the grassland (44.71 ppm). Bulk density, porosity, and total nitrogen were not found to be significantly different and other soil properties were found to be significantly different between different land use systems. The contribution of farmers in maintaining soil properties on the farmlands is clearly reflected in the results, so their knowledge on soil management needs to be explored and adapted for wise use and sustainable management of other land use systems.

Description: The objective of the study is to investigate the effect of released silicon (Si) and aluminum (Al) during the formation of volcanic ash soil on the content of Si in groundwater on Jeju Island. Volcanic ash soils in Jeju Island were formed from pyroclastic materials that originated from basalt. We sampled four profiles, including basaltic bedrock of each soil series with large variations in elevation (160–320 m) and mean annual precipitation (MAP; 1,800–2,600 mm). The soil and bedrock minerals were analyzed for weathering of volcanic ash soils related to mineralogical transformations and mobility of Si and Al. Andisols (above 2,000 mm MAP) were dominantly composed of allophane and gibbsite. In Andisols used in the study, 10–70% of Si was lost, whereas the amount of Al was relatively conserved. This is because Al forms Al-humus complex and Andisols contain allophane. In contrast, non-Andisols located at low altitude with lower than 1,800 mm MAP were enriched with considerable amounts of Si and Al, because non-Andisols have crystalline clay minerals and quartz. These results indicate that Andisols, which are widely distributed in Jeju Island, may play an important role in contributing to the high concentration of dissolved Si in the groundwater.

Description: Termite mounds are replete with natural nanoparticles, and they vary in physicochemical, geochemical, mineralogical, and biological properties from the adjoining soils. Although termite mounds have wide ecological and environmental roles including soil formation, faunal and vegetation growth and diversity, organic matter decomposition, geochemical exploration, water survey, treatment of underground contamination, thermoregulation, gas exchange, and global climate change, their nanoscale structures made by the associated organomineral complexes are still poorly understood because of technical limitations. In this review, we highlight the ecological and environmental significance of termite mounds and the documented techniques that have been successfully used to study nanostructure of termite mounds, namely, midinfrared spectroscopy (MIRS), photogrammetry and cross-sectional image analysis, a combination of transmission electron microscopy (TEM) and pyrolysis field ionization mass spectrometry (Py-FIMS), scanning transmission X-ray microscopy (STXM) using synchrotron radiation in conjunction with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and high-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) for further appraisals. There is a need to continually develop and integrate nanotechnology with the routine classical soil analysis methods to improve our understanding of the functional mechanisms of nanostructure of termite mounds that are responsible for specific properties. In view of the numerous roles termite mounds play in the environments, agriculture, and engineering, there is no better time to channel much research into understanding how they function at nanoscale.

Description: It is widely recognized that vegetation plays a significant role in contrasting slope instability through the root reinforcement. The main objectives of this paper are to evaluate the root tensile of selected Pennisetum species, namely, P. pedicellatum (PPd) and P. polystachion (PPl), and to determine the soil shear strength of root-permeated soil from these species. The selected species were initially planted in the polybags using the hydroseeding technique. A mineral fertilizer of NPK ratio 10 : 8 : 10 was adopted in the hydroseeding mixture. Routine watering program was applied twice a day throughout growth observation for six months. Four replications were prepared for each species including a set of control polybags, which contained only soil for reference and comparison. The results of root tensile tests revealed the significant relationships between root diameter and tensile force. In comparison, the PPl was still indicated by higher values of root tensile force than PPd. The presence of roots clearly has contributed to the shear stress of root-permeated soils. The root density based on root biomass measurement attributed to the higher value of peak shear stress as achieved by PPl than PPd. The combined effects of root tensile and the soil shear strengths of this selected species can be used as biological materials in slope protection against erosion.

Description: Phytoremediation of hydrocarbon-contaminated soils is a challenging process. In an effort to enhance phytoremediation, soil was artificially contaminated with known concentration of light crude oil containing Total petroleum hydrocarbon (TPH) at a concentration of 75 gkg−1 soil. The contaminated soil was subjected to phytoremediation trial using four plant species (Oryza longistaminata, Sorghum arundinaceum, Tithonia diversifolia, and Hyparrhenia rufa) plus no plant used as control for natural attenuation. These phytoremediators were amended with concentrations (0, 5 and 10 gkg−1 soil) of organic manure (cow dung). Results at 120 days after planting, showed that application of manure at concentrations of 5 and 10 gkg−1 soil combined with an efficient phytoremediator can significantly enhance reduction of TPH compared to natural attenuation or use of either manure or a phytoremediator alone (p0.05). Therefore, the study concludes that use of phytoremediators and manure 5 gkg−1 soil could promote the restoration of TPH contaminated-soils in the Sudd region of South Sudan.

Description: Decomposition is a key flux of terrestrial carbon to the atmosphere. Therefore, gaining a better understanding of how plant litter decomposes in soil, and what governs this process, is vital for global climate models. The Tea Bag Index (TBI) was introduced by Keuskamp et al. (2013) as a novel method for measuring litter decomposition rate and stabilisation. The TBI uses two types of tea bags representing fast (green tea) and slow (rooibos tea) decomposition substrates as standardised litter bags. To date, the TBI method has been used in over 2000 locations across the globe. However, before now, there has been no information on how the composition of the tea leaves change during incubation. These data are crucial in determining the validity of the use of the TBI method globally, to ensure the tea leaves decompose in a way that is representative of so-called “native” litters. To provide chemical underpinning of the TBI method, a laboratory incubation of the tea bags was conducted with destructive sampling at 0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, and 91 d. The incubated tea was analysed for total C and N. In addition, C was characterised as alkyl, O-alkyl, aromatic, or carbonyl C using solid-state 13C nuclear magnetic resonance spectroscopy with cross-polarization and magic angle spinning (CPMAS NMR). The results suggest that changes in carbon in both tea types are comparable to other litter studies, with a net decrease in total C and relative proportion of O-alkyl C fraction, which contains carbohydrates and cellulose. We conclude that the decomposition of tea leaves in the bags used in the TBI is representative of other litters.

Description: As an effect of intensive agricultural development of the steppes of the northern Black Sea coast, the finds of postantique agricultural landscapes that preserve relic elements of ancient land-use infrastructure are extremely rare. To these belongs the uniquely preserved ancient Greek land division system on the Tarkhankut Peninsula (north-western Crimea), which was studied using the methods of soil science and biomorphic analysis. This paper explores ancient land-use practices in order to reconstruct the original parameters of the land division system, as well as agricultural techniques employed. For postantique agricultural landscapes, an integrated geoarchaeological approach that includes GIS and remote sensing methodologies, in-field study of microrelief and soil registrograms, pedochronological dating technique, and physicochemical, geochemical, and biomorphic soil analyses has been developed and tested. The soil-geomorphological reconstruction shows that the Hellenistic land division system included a 4.5–4.9 m wide strip of land bordered by a 4.1–4.7 m wide (at the base) and c. 0.2 m high wall and a c. 2 m wide and over 15 cm deep trench, which controlled surface runoff and erosion. Ancient agricultural practices of slope farming resembled the modern ones. Surface runoff and soil erosion were controlled by dividing the catchment area into narrow plots, the borders of which on arable land were marked by simple earthen structures (low walls with shallow trenches). The biomorphic analysis of soil sampled atop these structures indicates that in ancient times, these earthen walls were not cultivated. The study of conservative properties preserved in pedomemory of postagrogenic soils provided valuable evidence of agricultural techniques used in the palaeogeographic conditions of the 4th and 3rd centuries BC.

Description: Soil conservation practices such as cover crops can improve crop production, soil quality, and water quality. Cover crops can also influence soil microbial growth and activity. Cover cropped and manured soils can potentially store and transmit fecal bacteria (e.g., E. coli) to surface water if runoff and subsurface seepage occur. While many studies have shown the soil health benefits of cover crops, fewer studies have evaluated the extent to which cover crops influence the abundance of potential waste-borne pathogens. A two-year study (2015–2017) was conducted on a limited-resource farm in Logan County, Kentucky, USA, to quantify the abundance of the fecal indicator Escherichia coli (E. coli) bacteria (as a proxy for fecal coliforms) in treatments with and without cover crops or composted poultry litter. The cover crop consisted of a cereal rye (Secale cereale L.), Austrian winter pea (Pisum sativum L.), and crimson clover (Trifolium incarnatum L.) mix. Summer crops consisted of a no-till maize (Zea mays L.)—soybean (Glycine max L.) rotation. Soil samples were taken before and after each summer crop season and assessed to detect and enumerate E. coli. At the end of the study period, no significant treatment differences in the E. coli abundance in soil were detected (ca. 104 CFU·g−1) (p〉0.05). However, season/time was a significant factor (p

Description: This research aimed to address health and food security challenges affecting Los Angeles and beyond in our own backyard. One possible way to combat these challenges is through biotechnology. The purpose of this research was to characterize the arable soils at Los Angeles Pierce College and their potential uses. The methods employed were collection of soil physical and chemical properties, cultivation of soil microorganisms, and 16S rDNA sequencing with a citizen science platform. Statistical analysis in R revealed associations between field conditions and life in the soil. The testing of plant-based antimicrobial agents on antibiotic-resistant bacteria revealed that plant oils could be more efficacious for control than common antibiotics. We found evidence of plant growth-promoting, antibiotic-producing, and bioremediating bacteria in different fields with distinct microclimates based on the 16S rDNA taxonomy results and inferred functional profiles. The major findings included an abundance of Streptomyces, Bacillus, Methylobacteria, and others with desirable functions. Numerous Streptomyces isolates cultivated on selective media demonstrated the ability to reduce nitrate. These results will empower future trials and product development by identifying target soil microorganisms and the most viable fields.

Description: Land degradation is a global negative environmental process that causes the decline in the productivity of land resources’ capacity to perform their functions. Though soil and water conservation (SWC) technologies have been adopted in Geshy subcatchment, their effects on soil quality were limitedly studied. The study was conducted to evaluate the effects SWC measures on soil quality indicators in Geshy subcatchment, Gojeb River Catchment, Ethiopia. A total of 54 soil samples (two treatments–farmlands with and without SWC measures ∗ three slope classes ∗ three terrace positions ∗ three replications) were collected at a depth of 20 cm. Statistical differences in soil quality indicators were analyzed using multivariate analysis of variance (ANOVA) following the general linear model procedure of SPSS Version 20.0 for Windows. Means that exhibited significant differences were compared using Tukey’s honest significance difference at 5% probability level. The studied soils are characterized by low bulk density, slightly acidic with clay and clay loam texture. The results revealed that farmlands with SWC measures had significantly improved soil physical (silt and clay fractions, and volumetric soil water content (VSWC)) and chemical (pH, SOC, TN, C : N ratio, and Av. phosphorus) quality indicators as compared with farmlands without SWC measures. The significantly higher VSWC, clay, SOC, TN, C : N ratio, and Av. P at the bottom slope classes and terrace positions could be attributed to the erosion reduction and deposition effects of SWC measures. Generally, the status of the studied soils is low in SOC contents, TN, C : N ratio, and Av. P (deficient). Thus, integral use of both physical and biological SWC options and agronomic interventions would have paramount importance in improving soil quality for better agricultural production and productivity.

Description: Mining processes generate waste rock, tailings, and slag that can increase potentially toxic metal (PTM) concentrations in soils. Un-reclaimed, abandoned mine sites are particularly prone to leaching these contaminants, which may accumulate and pose significant environmental and public health concerns. The characterization and spatial delineation of PTMs in soils is vital for risk assessment and soil reclamation. Bumpus Cove, a once active mining district of eastern Tennessee, is home to at least 47 abandoned, un-reclaimed mines, all permanently closed by the 1950s. This study evaluated soil physicochemical properties, determined the spatial extent of PTMs (Zn, Mn, Cu, Pb, and Cd), and examined the influence of soil properties on PTM distribution in Bumpus Cove, TN. Soil samples (n = 52) were collected from a 0.67 km2 study area containing 6 known abandoned Pb, Zn, and Mn mines at the headwaters of Bumpus Cove Creek. Samples were analyzed for Zn, Mn, Cu, Pb, and Cd by microwave-assisted acid digestion and flame atomic absorption spectrometry (FAAS) (12–1,354 mg/kg Zn, 6–2,574 mg/kg Mn, 1–65 mg/kg Cu, 33–2,271 mg/kg Pb, and 7–40 mg/kg Cd). Of the measured PTMs, only Pb exceeds permissible limits in soils. In addition to the PTM analyses, soil physical (texture, moisture content, and bulk density) and chemical (pH, cation exchange capacity (CEC), and total organic carbon (TOC)) properties were evaluated. Spatially weighted multivariate regression models developed for all PTMs using soil physicochemical properties produced improved results over ordinary least squares (OLS) regression models. Models for Zn (R2 = 0.71) and Pb (R2 = 0.69) retained covariates epH, moisture content, and CEC (Zn), and pH and CEC (Pb). This study will help define PTM concentration and transport and provide a reference for state and local entities responsible for contaminant monitoring in Bumpus Cove, TN.

Description: Discharging of untreated municipal solid wastes (MSWs) onto land is very widespread in developing countries. The compounds contained in MSW cause a harmful effect to human and environment. Hence, an assessment of the extent of their local impact is of great interest to figure out the pollution they cause. Therefore, this study aimed at evaluating the effects of discharge of solid wastes on soil quality within the landfill of Ain-El-Hammam municipality (Algeria). To achieve this, different soil physicochemical parameters were considered: granulometry, electrical conductivity, pH, organic matter content, and heavy metal concentration. The results indicated the influence of the MSW on the physicochemical characteristics of the soil by enhancing the organic matter content of soil (4.53%) and increasing heavy metal content (Cu, Zn, Cd, Pb, Ni, and Cr), which is a clear indication of the level of pollution they are generating.

Description: Over the past ten years, more than twenty fires have affected the El Noviciado estate located in Cerro Majuy, Colombia, leading to a loss of soil nutrients and infertility. Lysinibacillus sphaericus, a Gram-positive, mesophilic, and spore-forming bacterium, can be used in soil amendment in the replantation processes, given its ability to fix nitrogen, and nitrify, and solubilize phosphorus, increasing soil nutrients used for plant growth. In this study, we evaluated the soil-amendment potential of L. sphaericus by monitoring the nutrient content of a selected fragment of soil in the El Noviciado estate. For this purpose, we added a mixture of L. sphaericus OT4b.31, OT4b.49, CBAM5, III(3)7, and 2362 strains and determined the ammonium, nitrites, nitrates, phosphorus, and indole acetic acid concentrations in soil. Alnus acuminata sbsp. acuminata, a native model plant known for its restoration effect, was used for replantation. Results indicated that soils with added L. sphaericus presented significant differences in ammonium, nitrites, nitrates, phosphorus, and indole acetic acid concentrations when compared to control soils. Further, results showed no significant differences between soil that had been pre-inoculated in greenhouse and soil directly inoculated in field. We propose that L. sphaericus could be a good nutrient enhancer and plant growth promoter that can be used for the amendment of fire-impacted soils and replantation treatments.

Description: Soil properties contribute to the widely recognised resilience of semiarid areas. However, limited attention has been given in providing a scientific basis of how semiarid soil properties in the various land covers occur and how they influence forage quantity. This study investigated the influence of different soil properties and land cover types on herbaceous biomass quantity in the Karamoja subregion of Uganda. A completely randomized design in three land cover types (thickets and shrublands, woodlands, and savannah grasslands) was implemented. In each vegetation type, 50 × 40 m plots were demarcated with nested plots to facilitate clipping of the herbaceous layer. Composite soil samples at two depths (0–15 cm, 15–30 cm) were obtained from each plot. The results showed that soil properties varied across land cover types. Soil pH ranged between 6.9 and 8.1 and SOM, N, P, and K were generally low in all land cover types. Soil hydraulic properties revealed the existence of rapid to very rapid permeability in thickets/shrublands, grasslands, and woodlands. Percent change in soil properties (0–15 cm to 15–30 cm) was highest in P, Ca, Mg, Na, and SOM. In the grasslands, P positively () influenced herbaceous biomass, whereas pH, K, Na, % sand, and % clay, N, and SOM had a negative relationship with herbaceous biomass (). Herbaceous biomass in the thickets/shrublands was negatively influenced by P, Ca, and Mg and % clay and positively by N and % silt (). Only N and SOM were significant determinants of herbaceous biomass in the woodlands (). The low level of soil nutrients observed in this study reveals the fragility of semiarid soils, indicating the need for sustainable landscape management.

Description: Little is known about soil nutrient practice effects on soil moisture under cereal cropping systems. The objective of this research was to evaluate soil moisture content (SMC) response to short-term nitrogen (N) and phosphorus (P) fertilizer rates applied on tef crop varieties and their interactions. A rain-fed fertilizer experiment using tef varieties as the test crop was conducted for two years (2012-2013) in the Chromic Cambisols of northern Ethiopia. The experimental design was laid down in randomized complete block design with three replications. Two treatment factors, namely, fertilizer (four N + P rates) and variety (three tef varieties), were tested. Soil samples were taken at different tef crop growth stages or days after sowing time (DAS) to determine SMC using the gravimetric method. Data were analyzed at a probability level of 0.05. The fertilizer treatments significantly affected the SMC determined at the different tef growth stages and cropping seasons. The highest SMC was determined at 33 DAS (51 m3·m−3), but SMC decreased with increasing fertilizer rates. A higher SMC response to local tef variety than improved variety was found across all the growth stages and cropping seasons. There were also significant differences in SMC among the treatment interactions determined at the different growth stages and across the years. The paired mean differences in SMC due to the treatments between the two years were strongly correlated (r 〉 0.90, ). For SMC response being effective to fertilizer and its interaction effect with variety, it is suggested that soil management practices that improve moisture such as organic sources should be integrated with the inorganic fertilizer in the conditions of Chromic Cambisols in northern Ethiopia.

Description: The impact of different land-use systems on some soil physicochemical properties and macrofauna abundance in the humid tropics of Cameroon was studied. The land-use types included secondary forest (SF), oil palm plantation (PP), banana plantation (BP), sugarcane plantation (SP), and rubber plantation (RP). Soil particle size distribution, bulk density (BD), pH, organic matter (OM), and number of macrofauna were evaluated. The results showed that OM and number of macrofauna were higher in the SF than in the other land-use types. Pearson’s correlation analysis carried out to determine the relationship between OM and BD showed that OM and BD was strongly negatively related with correlation coefficient of −0.9653. It also showed a strong significant negative correlation between BD and ants population (r = −0.8828) and between soil pH and number of earthworms (r = −0.9072). Based on the results, the SF produced more organic matter and higher number of macrofauna. However, the OM of the other land uses was not low; hence, it could be beneficial to return plant residues to the field for maintaining soil quality.

Description: A study was conducted in the Sabal area, Sarawak, to evaluate the physicochemical properties of sandy-textured soils under smallholder agricultural land uses. Study sites were established under rubber, oil palm, and pepper land uses, in comparison to the adjacent secondary forests. The sandy-textured soils underlain in all agricultural land uses are of Spodosols, based on USDA Soil Taxonomy. The soil properties under secondary forests were strongly acidic with poor nutrient contents. Despite higher bulk density in oil palm farmlands, soil properties in rubber and oil palm land uses showed little variation to those in secondary forests. Conversely, soils under pepper land uses were less acidic with higher nutrient contents at the surface layer, especially P. In addition, soils in the pepper land uses were more compact due to human trampling effects from regular farm works at a localized area. Positive correlations were observed between soil total C and soil total N, soil exchangeable K, soil sum of bases, and soil effective CEC, suggesting that soil total C is the determinant of soil fertility under the agricultural land uses. Meanwhile, insufficient K input in oil palm land uses was observed from the partial nutrient balances estimation. In contrast, P and K did not remain in the soils under pepper land use, although the fertilizers application by the farmers was beyond the crop uptake and removal (harvesting). Because of the siliceous sandy nature (low clay contents) of Spodosols, they are poor in nutrient retention capacity. Hence, maintaining ample supply of organic C is crucial to sustain the productivity and fertility of sandy-textured soils, especially when the litterfall layers covering the E horizon were removed for oil palm and pepper cultivation.

Description: Land use and land cover in the Dano catchment is characterized by a rapid conversion from seminatural vegetation (fallow) to agriculture (cropland). The study compares both the saturated (Ks) and the unsaturated (Kh) hydraulic conductivities under cropland and fallow in the catchment to gain insights into the effect of the current land use on soil water dynamics. Hydraulic conductivity was measured under forty-two (42) pairs of adjacent cropland-fallow plots using a Hood infiltrometer. Ks, Kh, bulk density, and soil texture were further compared using a paired two-tailed Student’s t-test (). The results showed that both Ks and Kh are highly variable irrespective of the land use type (coefficient of variation 〉 100%). The results also showed that Ks was significantly higher (1.16-fold on average) under fallow compared to cropland. As for Kh, the results showed that, from −2 cm to zero tension heads (h), Kh under cropland and fallow is not significantly different; however, as the supplied tension decreases up to the saturation state, Kh under fallow becomes statistically higher compared to cropland. No significant difference was found between soil textures and bulk density under cropland and fallow meaning that the observed differences of Ks and Kh under cropland and fallow were caused by land use and not preexisting difference in texture. These results suggest an increasing risk of erosion, soil fertility reduction, and flood in the catchment because of agricultural land expansion.

Description: Land degradation caused by improper land use management is a critical worldwide problem that has revived the issue of resources sustainability. Soil degradation, which involves physical, chemical, and biological degradation, is the key component of land degradation. Assessment of soil quality (SQ) indicators that distinguish soil degradation in different land use (LU) types is enviable to achieve sustainable land management strategies. The objective of this study was to assess the effects of land uses on soil quality indicators in the Geshy subcatchment of the Gojeb River Catchment, Omo-Gibe Basin, Ethiopia. The LU types identified for evaluation included natural forest, cultivation, and grazing lands. Accordingly, a total of 54 soil samples (three LU types × three slope classes (blocks) × three replications × two soil depths) were collected with an “X” plot design for data analysis. Statistical differences in SQ indicators were analyzed among LU types, slope classes, and soil depths and tested using univariate analysis of variance and Pearson’s correlation coefficient, following the general linear model. The results showed that a number of SQ indicators were significantly influenced by LU changes and soil depths. The sand, dry soil bulk density , volumetric soil water contents (VSWC), total porosity, water infiltration rates, cumulative infiltration, and total nitrogen showed significant variations between the natural forest and the other LU types and soil depths (). However, silt, clay, soil pH, SOC contents, carbon-to-nitrogen ratio, and available phosphorus did not show significant variations between LU types and soil depths (). The overall qualities of the soils under the cultivation land were inferior in VSWC, TP, water infiltration rates, SOC contents, and TN soil attributes of the adjacent natural forest and grazing lands. The studied soils were found to be dominantly of clays with slightly acidic and low SOC contents and slow in their infiltration rate. Thus, integrated and sustainable land management, aimed at enhancing proper LU systems, is crucial for the sustainable ecosystem functioning and is the most effective way in reversing of soil quality deterioration.

Description: The agricultural use of domestic sewage is a viable alternative for recycling nutrients; however, there is concern regarding the impact of its use due to the concentration of chemical elements present in this type of effluent. The use of principal component analysis determines the existence or lack of anomalous samples and the relations between measured variables and their relative contribution among samples that help in monitoring the impact of the use of effluents on soil chemical components. Thus, the objective of this work was to identify nutrient ions present in the soil solution during the first ratoon sugarcane irrigated with treated domestic sewage applied by subsurface drip irrigation. The experiment was conducted under a randomized block design with 5 treatments and 5 replicates. The treatments were distributed according to the type of water applied in the irrigation system (water surface reservoir and treated domestic sewage), the installation depth of the drip tapes (0.2 or 0.4 m depth), and the treatment without irrigation. By means of soil solution, it was possible to identify an increase in the concentration of salts in the treatments irrigated with treated domestic sewage, which however did not affect the soil quality in the short term. The principal component analysis selected the variables Ca2+, Mg2+, NO3−, K+, and EC as soil solution indicators to monitor areas irrigated with treated domestic sewage.

Description: Multi-soil-layering (MSL) wastewater treatment systems consist of soil units (soil mixture blocks, SMB) arranged in a brick-like pattern surrounded by permeable layers of zeolite or alternating particles of homogeneous sizes that allow for a high hydraulic loading rate. This study evaluated the performances of MSL systems that have been operating for 17 to 20 years in small rural communities. Even though 20 years had passed since this system was installed, high organic matter treatment performance continued. Nitrogen removal was higher than with conventional soil systems. Two of the MSL systems continued to show high phosphorus removal performances, whereas in the third system, the adsorbing capacity was relatively low, requiring further investigation. Treatment performances were largely dependent upon the structure of the MSL systems. It appeared that improving the structure to enhance the contact efficiency between the wastewater and the soil in SMB was important for enhancing treatment performances. The combined use of existing wastewater treatment systems with the MSL system was effective for preventing environmental pollution over a long period.

Description: Using waste materials from industrial activities to build anthroposols (soils built or altered by humans) can provide soil for reclamation and reduce amounts of materials stored in landfills. Mines and other large industrial disturbances requiring anthroposols usually have large amounts of nonorganic waste materials with low water holding capacity and large amounts of coarse fragments. Thus, water holding capacity is a key property to build into anthroposols as all aspects of revegetation are strongly influenced by soil water content. This research assessed the effectiveness of hydrogel and organic amendments to increase the water retention in common mine wastes used to build anthroposols for reclamation in three greenhouse experiments. Waste materials were crushed rock, lakebed sediment, and processed kimberlite, from a northern diamond mine in Canada. Amendments were hydrogel, sewage, salvaged soil, and peat. Pots were filled with the material and weighed and saturated, followed by periodic weighing until the weight was near constant. Water retention was consistently highest in processed kimberlite, with and without amendments. Water retention increased most with hydrogel in processed kimberlite and crushed rock. Hydrogel application method impacted the initial water retention, but over time, the effect was limited. Water retention in lakebed sediment showed little difference relative to no amendment addition and had lowest increases relative to other substrates. Type of waste material and amendment, application rate, and application method impacted water retention and can be adapted to build anthroposols in the field using waste materials suitable for reclamation.

Description: In soils, dissolved silicon (Si) is adsorbed onto soil particles or is leached into groundwater through the soil profile. Andisols may play an important role in contributing to high dissolved Si concentrations in groundwater on Jeju Island, Korea. In this study, we evaluated the available Si content that potentially affects groundwater composition and investigated the relationship between the available Si content and chemical properties of volcanic ash soil on Jeju Island. We used the 1 M sodium acetate buffer (pH 4.0) to extract the available Si. Selected chemical properties were determined for 290 topsoil samples collected from different land sites throughout Jeju Island, and we analyzed the available Si content in the typifying pedons of Jeju Island and mainland Korea. The available Si content in Jeju Island topsoils ranged from 75 to 150 mg·kg−1, and the available Si content of Andisols in both orchards and grasslands was significantly higher than that of non-Andisols. The available Si content was highly correlated with the amounts of oxalate extractable Si, Al, and Fe in Andisols and was negatively related to the Alp/Alo ratio. With increasing elevation, we detected a decrease in the available Si and allophane content in Andisols, whereas Al-humus complexes increased with increasing elevation. The ratio of available Si in the lowest subsoil/topsoil increased to a value of 6.0, indicating that large amounts of available Si are present in the subsoil. The available Si content in the lowest subsoil of Andisols on Jeju Island was 10 times higher than that in the typifying pedons of the Korean mainland. In contrast, there were no differences in the available Si content between the topsoil and the subsoil of the typifying pedon series of Jeju and mainland non-Andisols because of differences in pedogenic processes. Collectively, our findings indicate that weathering of Andisols on Jeju Island potentially affects the Si concentration in groundwater.

Description: In the natural environment, soil pH has an enormous influence on soil biogeochemical processes. Soil pH is, therefore, described as the “master soil variable” that influences myriads of soil biological, chemical, and physical properties and processes that affect plant growth and biomass yield. This paper discusses how soil pH affects processes that are interlinked with the biological, geological, and chemical aspects of the soil environment as well as how these processes, through anthropogenic interventions, induce changes in soil pH. Unlike traditional discussions on the various causes of soil pH, particularly soil acidification, this paper focuses on relationships and effects as far as soil biogeochemistry is concerned. Firstly, the effects of soil pH on substance availability, mobility, and soil biological processes are discussed followed by the biogenic regulation of soil pH. It is concluded that soil pH can broadly be applied in two broad areas, i.e., nutrient cycling and plant nutrition and soil remediation (bioremediation and physicochemical remediation).

Description: Flooded ecosystems are conditioned to seasonal floods that promote specific soil conditions, such as low oxygen, hydromorphism, and peculiar chemical reactions. These environments are dependent on flood pulses that determine specific ecological conditions. Ipucas are seasonally flooded discontinuous forest patches that occur exclusively in the Araguaia Plain in Central Brazil. They are located 0.40 to 1.20 m lower than the surrounding plain, which promotes an accumulation of rainwater for five to six months of the year, being entirely or partially dry during the dry season. The aim of this study was to evaluate the horizontal (centre and edge) and vertical (depths: 0–0.20 m and 0.20–0.40 m) variability of physicochemical parameters in Ipucas soils, attempting to establish the importance of flood pulses and the leaching of surrounding areas in soil formation and composition. Samples were collected during the dry season in three Ipucas of similar size and circularity using a Dutch auger. The results reveal that flood pulses promote the deposition of sediments eroded from the surrounding plain, homogenizing the characteristics of the surface soil, from the edge to the centre of the Ipucas. However, biogeochemical processes, also linked to temporary flooding, account for the differences between the surface and deeper soil horizons because anoxic conditions during flooding promote chemical reactions characteristic of anaerobic environments, modifying the pH and organic matter content, in addition to the gleying of soils subjected to flooding, which are then covered by sediments after the dry season. Finally, Ipucas soils are susceptible to anthropic changes and are dependent on seasonal flood pulses.

Description: Crop rotation systems especially dominated by cereals (maize and wheat) are intimately linked to soil properties. The objective of the study was to investigate the effect of crop rotations and conservation practice on selected soil physicochemical properties in northwestern part of Ethiopia. Soil samples (0–20 cm depth) were collected from seven crop rotations with conservation practice and adjacent fields without any conservation measure in three replications. A total of forty-two composite samples were used for analysis by using SAS software. The land rotated with maize-wheat-faba bean exhibited significantly higher mean bulk density (1.06 g/cm3) than the land rotated with other crops (i.e., ranging from 1.02 to 1.04 g/cm3). Mean values of pH (5.34, 4.98, and 5.4), Ex. acidity (2.03, 2.53, and 2.16 cmolc/kg), soil OM (4.53%, 5.12%, and 5.02%), CEC (45.17, 48.03, and 49.47 cmolc/kg), TN (0.23, 0.25, and 0.27%), Av.P (10.21, 7.23, and 7.95 ppm), and C : N ratio (11.18, 11.95, and 10.8) were recorded under rotations with continuous maize, maize-pepper-pepper, and maize-faba bean-pepper, respectively. Mean values of pH (5.34 and 4.97), Av.P (9.51 and 6.53 ppm), CEC (48.3 and 46.87 cmolc/kg), and Ex. acidity (2.5 and 2.85 cmolc/kg) were also recorded under conserved and unconserved farmlands, respectively. Considering the interaction effect of crop rotations by conservation practice, all studied parameters, except bulk density, CEC, and C : N ratio, were significantly () affected. The findings indicate that although continuous maize showed good content of available P and low exchangeable acidity, it will deplete particular nutrients; therefore, maize-pepper-pepper, maize-wheat-faba bean, and maize-faba bean-pepper recorded a slight trend of good values in studied soil physicochemical properties compared to other rotations. A critical study on such type of issue should be carried out over a longer period of time in order to announce detailed understanding about response of soil property to crop rotations to the community.

Description: Soil erosion is one of the main forms of land degradation. Erosion contributes to loss of agricultural land productivity and ecological and esthetic values of natural environment, and it impairs the production of safe drinking water and hydroenergy production. Thus, assessment of soil erosion and identifying the lands more prone to erosion are vital for erosion management process. Revised Universal Soil Loss Equation (Rusle) model supported by a GIS system was used to assess the spatial variability of erosion occurring at Kalu Ganga river basin in Sri Lanka. Digital Elevation Model (30 × 30 m), twenty years’ rainfall data measured at 11 rain gauge stations across the basin, land use and soil maps, and published literature were used as inputs to the model. The average annual soil loss in Kalu Ganga river basin varied from 0 to 134 t ha−1 year−1 and mean annual soil loss was estimated at 0.63 t ha−1 year−1. Based on erosion estimates, the basin landscape was divided into four different erosion severity classes: very low, low, moderate, and high. About 1.68% of the areas (4714 ha) in the river basin were identified with moderate to high erosion severity (〉5 t ha−1 year−1) class which urgently need measures to control soil erosion. Lands with moderate to high soil erosion classes were mostly found in Bulathsinghala, Kuruwita, and Rathnapura divisional secretarial divisions. Use of the erosion severity information coupled with basin wide individual RUSLE parameters can help to design the appropriate land use management practices and improved management based on the observations to minimize soil erosion in the basin.

Description: Soil erosion is one of the main forms of land degradation. Erosion contributes to loss of agricultural land productivity and ecological and esthetic values of natural environment, and it impairs the production of safe drinking water and hydroenergy production. Thus, assessment of soil erosion and identifying the lands more prone to erosion are vital for erosion management process. Revised Universal Soil Loss Equation (Rusle) model supported by a GIS system was used to assess the spatial variability of erosion occurring at Kalu Ganga river basin in Sri Lanka. Digital Elevation Model (30 × 30 m), twenty years’ rainfall data measured at 11 rain gauge stations across the basin, land use and soil maps, and published literature were used as inputs to the model. The average annual soil loss in Kalu Ganga river basin varied from 0 to 134 t ha−1 year−1 and mean annual soil loss was estimated at 0.63 t ha−1 year−1. Based on erosion estimates, the basin landscape was divided into four different erosion severity classes: very low, low, moderate, and high. About 1.68% of the areas (4714 ha) in the river basin were identified with moderate to high erosion severity (〉5 t ha−1 year−1) class which urgently need measures to control soil erosion. Lands with moderate to high soil erosion classes were mostly found in Bulathsinghala, Kuruwita, and Rathnapura divisional secretarial divisions. Use of the erosion severity information coupled with basin wide individual RUSLE parameters can help to design the appropriate land use management practices and improved management based on the observations to minimize soil erosion in the basin.

Description: Selecting a suitable physical fractionation method, to investigate soil organic matter dynamics, from the plethora that are available is a difficult task. Using five different physical fractionation methods, on soils either nontreated or with a history of amendment with a range of exogenous organic matter inputs (Irish moss peat; composted horse manure; garden compost) and a resulting range of carbon contents (6.8 to 22.2%), we show that method selection had a significant impact on both the total C recovered and the distribution of the recovered C between unprotected, physically protected, or chemically protected conceptual pools. These between-method differences most likely resulted from the following: (i) variation in the methodological fractions obtained (i.e., distinguishing between aggregate size classes); (ii) their subsequent designation to conceptual pools (e.g., protected versus unprotected); and (iii) the procedures used in sample pretreatment and subsequent aggregate dispersion and fractionation steps. The performance of each method also varied depending on the amendment in question. The findings emphasise the need for an understanding of the nature of the soil samples under investigation, and the stabilisation mechanism of interest, both prior to method selection and when comparing and interpreting findings from literature studies using different fractionation methods.

Description: In the natural environment, soil pH has an enormous influence on soil biogeochemical processes. Soil pH is, therefore, described as the “master soil variable” that influences myriads of soil biological, chemical, and physical properties and processes that affect plant growth and biomass yield. This paper discusses how soil pH affects processes that are interlinked with the biological, geological, and chemical aspects of the soil environment as well as how these processes, through anthropogenic interventions, induce changes in soil pH. Unlike traditional discussions on the various causes of soil pH, particularly soil acidification, this paper focuses on relationships and effects as far as soil biogeochemistry is concerned. Firstly, the effects of soil pH on substance availability, mobility, and soil biological processes are discussed followed by the biogenic regulation of soil pH. It is concluded that soil pH can broadly be applied in two broad areas, i.e., nutrient cycling and plant nutrition and soil remediation (bioremediation and physicochemical remediation).

Description: Histoplasma capsulatum (H. capsulatum) is a thermal-dimorphic fungus, the causal agent of histoplasmosis. Its presence in the environment is related with chicken manure due to their high nitrogen and phosphorus content. In Colombia, chicken manure is the most used raw material in the composting process; however, there is no information about the capacity of H. capsulatum to survive and remain viable in a composted organic fertilizer. To address this question, this study shows three assays based on microbiological culture and the Hc100 nested PCR. First, a composting reactor system was designed to transform organic material under laboratory conditions, and the raw material was inoculated with the fungus. From these reactors, the fungus was not isolated, but its DNA was detected. In the second assay, samples from factories where the DNA of the fungus was previously detected by PCR were analyzed. In the raw material samples, 3 colonies of H. capsulatum were isolated and its DNA was detected. However, after the composting process, neither the fungus was recovered by culture nor DNA was detected. In the third assay, sterilized and nonsterilized organic composted samples were inoculated with H. capsulatum and then evaluated monthly during a year. In both types of samples, the fungus DNA was detected by Hc100 nested PCR during the whole year, but the fungus only grew from sterile samples during the first two months evaluated. In general, the results of the assays showed that H. capsulatum is not able to survive a well-done composting process.

Description: Flooded ecosystems are conditioned to seasonal floods that promote specific soil conditions, such as low oxygen, hydromorphism, and peculiar chemical reactions. These environments are dependent on flood pulses that determine specific ecological conditions. Ipucas are seasonally flooded discontinuous forest patches that occur exclusively in the Araguaia Plain in Central Brazil. They are located 0.40 to 1.20 m lower than the surrounding plain, which promotes an accumulation of rainwater for five to six months of the year, being entirely or partially dry during the dry season. The aim of this study was to evaluate the horizontal (centre and edge) and vertical (depths: 0–0.20 m and 0.20–0.40 m) variability of physicochemical parameters in Ipucas soils, attempting to establish the importance of flood pulses and the leaching of surrounding areas in soil formation and composition. Samples were collected during the dry season in three Ipucas of similar size and circularity using a Dutch auger. The results reveal that flood pulses promote the deposition of sediments eroded from the surrounding plain, homogenizing the characteristics of the surface soil, from the edge to the centre of the Ipucas. However, biogeochemical processes, also linked to temporary flooding, account for the differences between the surface and deeper soil horizons because anoxic conditions during flooding promote chemical reactions characteristic of anaerobic environments, modifying the pH and organic matter content, in addition to the gleying of soils subjected to flooding, which are then covered by sediments after the dry season. Finally, Ipucas soils are susceptible to anthropic changes and are dependent on seasonal flood pulses.

Description: Mining processes generate waste rock, tailings, and slag that can increase potentially toxic metal (PTM) concentrations in soils. Un-reclaimed, abandoned mine sites are particularly prone to leaching these contaminants, which may accumulate and pose significant environmental and public health concerns. The characterization and spatial delineation of PTMs in soils is vital for risk assessment and soil reclamation. Bumpus Cove, a once active mining district of eastern Tennessee, is home to at least 47 abandoned, un-reclaimed mines, all permanently closed by the 1950s. This study evaluated soil physicochemical properties, determined the spatial extent of PTMs (Zn, Mn, Cu, Pb, and Cd), and examined the influence of soil properties on PTM distribution in Bumpus Cove, TN. Soil samples (n = 52) were collected from a 0.67 km2 study area containing 6 known abandoned Pb, Zn, and Mn mines at the headwaters of Bumpus Cove Creek. Samples were analyzed for Zn, Mn, Cu, Pb, and Cd by microwave-assisted acid digestion and flame atomic absorption spectrometry (FAAS) (12–1,354 mg/kg Zn, 6–2,574 mg/kg Mn, 1–65 mg/kg Cu, 33–2,271 mg/kg Pb, and 7–40 mg/kg Cd). Of the measured PTMs, only Pb exceeds permissible limits in soils. In addition to the PTM analyses, soil physical (texture, moisture content, and bulk density) and chemical (pH, cation exchange capacity (CEC), and total organic carbon (TOC)) properties were evaluated. Spatially weighted multivariate regression models developed for all PTMs using soil physicochemical properties produced improved results over ordinary least squares (OLS) regression models. Models for Zn (R2 = 0.71) and Pb (R2 = 0.69) retained covariates epH, moisture content, and CEC (Zn), and pH and CEC (Pb). This study will help define PTM concentration and transport and provide a reference for state and local entities responsible for contaminant monitoring in Bumpus Cove, TN.

Description: In soils, dissolved silicon (Si) is adsorbed onto soil particles or is leached into groundwater through the soil profile. Andisols may play an important role in contributing to high dissolved Si concentrations in groundwater on Jeju Island, Korea. In this study, we evaluated the available Si content that potentially affects groundwater composition and investigated the relationship between the available Si content and chemical properties of volcanic ash soil on Jeju Island. We used the 1 M sodium acetate buffer (pH 4.0) to extract the available Si. Selected chemical properties were determined for 290 topsoil samples collected from different land sites throughout Jeju Island, and we analyzed the available Si content in the typifying pedons of Jeju Island and mainland Korea. The available Si content in Jeju Island topsoils ranged from 75 to 150 mg·kg−1, and the available Si content of Andisols in both orchards and grasslands was significantly higher than that of non-Andisols. The available Si content was highly correlated with the amounts of oxalate extractable Si, Al, and Fe in Andisols and was negatively related to the Alp/Alo ratio. With increasing elevation, we detected a decrease in the available Si and allophane content in Andisols, whereas Al-humus complexes increased with increasing elevation. The ratio of available Si in the lowest subsoil/topsoil increased to a value of 6.0, indicating that large amounts of available Si are present in the subsoil. The available Si content in the lowest subsoil of Andisols on Jeju Island was 10 times higher than that in the typifying pedons of the Korean mainland. In contrast, there were no differences in the available Si content between the topsoil and the subsoil of the typifying pedon series of Jeju and mainland non-Andisols because of differences in pedogenic processes. Collectively, our findings indicate that weathering of Andisols on Jeju Island potentially affects the Si concentration in groundwater.

Description: Little is known about soil nutrient practice effects on soil moisture under cereal cropping systems. The objective of this research was to evaluate soil moisture content (SMC) response to short-term nitrogen (N) and phosphorus (P) fertilizer rates applied on tef crop varieties and their interactions. A rain-fed fertilizer experiment using tef varieties as the test crop was conducted for two years (2012-2013) in the Chromic Cambisols of northern Ethiopia. The experimental design was laid down in randomized complete block design with three replications. Two treatment factors, namely, fertilizer (four N + P rates) and variety (three tef varieties), were tested. Soil samples were taken at different tef crop growth stages or days after sowing time (DAS) to determine SMC using the gravimetric method. Data were analyzed at a probability level of 0.05. The fertilizer treatments significantly affected the SMC determined at the different tef growth stages and cropping seasons. The highest SMC was determined at 33 DAS (51 m3·m−3), but SMC decreased with increasing fertilizer rates. A higher SMC response to local tef variety than improved variety was found across all the growth stages and cropping seasons. There were also significant differences in SMC among the treatment interactions determined at the different growth stages and across the years. The paired mean differences in SMC due to the treatments between the two years were strongly correlated (r 〉 0.90, ). For SMC response being effective to fertilizer and its interaction effect with variety, it is suggested that soil management practices that improve moisture such as organic sources should be integrated with the inorganic fertilizer in the conditions of Chromic Cambisols in northern Ethiopia.

Description: Crop rotation systems especially dominated by cereals (maize and wheat) are intimately linked to soil properties. The objective of the study was to investigate the effect of crop rotations and conservation practice on selected soil physicochemical properties in northwestern part of Ethiopia. Soil samples (0–20 cm depth) were collected from seven crop rotations with conservation practice and adjacent fields without any conservation measure in three replications. A total of forty-two composite samples were used for analysis by using SAS software. The land rotated with maize-wheat-faba bean exhibited significantly higher mean bulk density (1.06 g/cm3) than the land rotated with other crops (i.e., ranging from 1.02 to 1.04 g/cm3). Mean values of pH (5.34, 4.98, and 5.4), Ex. acidity (2.03, 2.53, and 2.16 cmolc/kg), soil OM (4.53%, 5.12%, and 5.02%), CEC (45.17, 48.03, and 49.47 cmolc/kg), TN (0.23, 0.25, and 0.27%), Av.P (10.21, 7.23, and 7.95 ppm), and C : N ratio (11.18, 11.95, and 10.8) were recorded under rotations with continuous maize, maize-pepper-pepper, and maize-faba bean-pepper, respectively. Mean values of pH (5.34 and 4.97), Av.P (9.51 and 6.53 ppm), CEC (48.3 and 46.87 cmolc/kg), and Ex. acidity (2.5 and 2.85 cmolc/kg) were also recorded under conserved and unconserved farmlands, respectively. Considering the interaction effect of crop rotations by conservation practice, all studied parameters, except bulk density, CEC, and C : N ratio, were significantly () affected. The findings indicate that although continuous maize showed good content of available P and low exchangeable acidity, it will deplete particular nutrients; therefore, maize-pepper-pepper, maize-wheat-faba bean, and maize-faba bean-pepper recorded a slight trend of good values in studied soil physicochemical properties compared to other rotations. A critical study on such type of issue should be carried out over a longer period of time in order to announce detailed understanding about response of soil property to crop rotations to the community.

Description: Land degradation caused by improper land use management is a critical worldwide problem that has revived the issue of resources sustainability. Soil degradation, which involves physical, chemical, and biological degradation, is the key component of land degradation. Assessment of soil quality (SQ) indicators that distinguish soil degradation in different land use (LU) types is enviable to achieve sustainable land management strategies. The objective of this study was to assess the effects of land uses on soil quality indicators in the Geshy subcatchment of the Gojeb River Catchment, Omo-Gibe Basin, Ethiopia. The LU types identified for evaluation included natural forest, cultivation, and grazing lands. Accordingly, a total of 54 soil samples (three LU types × three slope classes (blocks) × three replications × two soil depths) were collected with an “X” plot design for data analysis. Statistical differences in SQ indicators were analyzed among LU types, slope classes, and soil depths and tested using univariate analysis of variance and Pearson’s correlation coefficient, following the general linear model. The results showed that a number of SQ indicators were significantly influenced by LU changes and soil depths. The sand, dry soil bulk density , volumetric soil water contents (VSWC), total porosity, water infiltration rates, cumulative infiltration, and total nitrogen showed significant variations between the natural forest and the other LU types and soil depths (). However, silt, clay, soil pH, SOC contents, carbon-to-nitrogen ratio, and available phosphorus did not show significant variations between LU types and soil depths (). The overall qualities of the soils under the cultivation land were inferior in VSWC, TP, water infiltration rates, SOC contents, and TN soil attributes of the adjacent natural forest and grazing lands. The studied soils were found to be dominantly of clays with slightly acidic and low SOC contents and slow in their infiltration rate. Thus, integrated and sustainable land management, aimed at enhancing proper LU systems, is crucial for the sustainable ecosystem functioning and is the most effective way in reversing of soil quality deterioration.

Description: Over the past ten years, more than twenty fires have affected the El Noviciado estate located in Cerro Majuy, Colombia, leading to a loss of soil nutrients and infertility. Lysinibacillus sphaericus, a Gram-positive, mesophilic, and spore-forming bacterium, can be used in soil amendment in the replantation processes, given its ability to fix nitrogen, and nitrify, and solubilize phosphorus, increasing soil nutrients used for plant growth. In this study, we evaluated the soil-amendment potential of L. sphaericus by monitoring the nutrient content of a selected fragment of soil in the El Noviciado estate. For this purpose, we added a mixture of L. sphaericus OT4b.31, OT4b.49, CBAM5, III(3)7, and 2362 strains and determined the ammonium, nitrites, nitrates, phosphorus, and indole acetic acid concentrations in soil. Alnus acuminata sbsp. acuminata, a native model plant known for its restoration effect, was used for replantation. Results indicated that soils with added L. sphaericus presented significant differences in ammonium, nitrites, nitrates, phosphorus, and indole acetic acid concentrations when compared to control soils. Further, results showed no significant differences between soil that had been pre-inoculated in greenhouse and soil directly inoculated in field. We propose that L. sphaericus could be a good nutrient enhancer and plant growth promoter that can be used for the amendment of fire-impacted soils and replantation treatments.

Description: Soil properties contribute to the widely recognised resilience of semiarid areas. However, limited attention has been given in providing a scientific basis of how semiarid soil properties in the various land covers occur and how they influence forage quantity. This study investigated the influence of different soil properties and land cover types on herbaceous biomass quantity in the Karamoja subregion of Uganda. A completely randomized design in three land cover types (thickets and shrublands, woodlands, and savannah grasslands) was implemented. In each vegetation type, 50 × 40 m plots were demarcated with nested plots to facilitate clipping of the herbaceous layer. Composite soil samples at two depths (0–15 cm, 15–30 cm) were obtained from each plot. The results showed that soil properties varied across land cover types. Soil pH ranged between 6.9 and 8.1 and SOM, N, P, and K were generally low in all land cover types. Soil hydraulic properties revealed the existence of rapid to very rapid permeability in thickets/shrublands, grasslands, and woodlands. Percent change in soil properties (0–15 cm to 15–30 cm) was highest in P, Ca, Mg, Na, and SOM. In the grasslands, P positively () influenced herbaceous biomass, whereas pH, K, Na, % sand, and % clay, N, and SOM had a negative relationship with herbaceous biomass (). Herbaceous biomass in the thickets/shrublands was negatively influenced by P, Ca, and Mg and % clay and positively by N and % silt (). Only N and SOM were significant determinants of herbaceous biomass in the woodlands (). The low level of soil nutrients observed in this study reveals the fragility of semiarid soils, indicating the need for sustainable landscape management.

Description: Using waste materials from industrial activities to build anthroposols (soils built or altered by humans) can provide soil for reclamation and reduce amounts of materials stored in landfills. Mines and other large industrial disturbances requiring anthroposols usually have large amounts of nonorganic waste materials with low water holding capacity and large amounts of coarse fragments. Thus, water holding capacity is a key property to build into anthroposols as all aspects of revegetation are strongly influenced by soil water content. This research assessed the effectiveness of hydrogel and organic amendments to increase the water retention in common mine wastes used to build anthroposols for reclamation in three greenhouse experiments. Waste materials were crushed rock, lakebed sediment, and processed kimberlite, from a northern diamond mine in Canada. Amendments were hydrogel, sewage, salvaged soil, and peat. Pots were filled with the material and weighed and saturated, followed by periodic weighing until the weight was near constant. Water retention was consistently highest in processed kimberlite, with and without amendments. Water retention increased most with hydrogel in processed kimberlite and crushed rock. Hydrogel application method impacted the initial water retention, but over time, the effect was limited. Water retention in lakebed sediment showed little difference relative to no amendment addition and had lowest increases relative to other substrates. Type of waste material and amendment, application rate, and application method impacted water retention and can be adapted to build anthroposols in the field using waste materials suitable for reclamation.

Description: The agricultural use of domestic sewage is a viable alternative for recycling nutrients; however, there is concern regarding the impact of its use due to the concentration of chemical elements present in this type of effluent. The use of principal component analysis determines the existence or lack of anomalous samples and the relations between measured variables and their relative contribution among samples that help in monitoring the impact of the use of effluents on soil chemical components. Thus, the objective of this work was to identify nutrient ions present in the soil solution during the first ratoon sugarcane irrigated with treated domestic sewage applied by subsurface drip irrigation. The experiment was conducted under a randomized block design with 5 treatments and 5 replicates. The treatments were distributed according to the type of water applied in the irrigation system (water surface reservoir and treated domestic sewage), the installation depth of the drip tapes (0.2 or 0.4 m depth), and the treatment without irrigation. By means of soil solution, it was possible to identify an increase in the concentration of salts in the treatments irrigated with treated domestic sewage, which however did not affect the soil quality in the short term. The principal component analysis selected the variables Ca2+, Mg2+, NO3−, K+, and EC as soil solution indicators to monitor areas irrigated with treated domestic sewage.

Description: A study was conducted in the Sabal area, Sarawak, to evaluate the physicochemical properties of sandy-textured soils under smallholder agricultural land uses. Study sites were established under rubber, oil palm, and pepper land uses, in comparison to the adjacent secondary forests. The sandy-textured soils underlain in all agricultural land uses are of Spodosols, based on USDA Soil Taxonomy. The soil properties under secondary forests were strongly acidic with poor nutrient contents. Despite higher bulk density in oil palm farmlands, soil properties in rubber and oil palm land uses showed little variation to those in secondary forests. Conversely, soils under pepper land uses were less acidic with higher nutrient contents at the surface layer, especially P. In addition, soils in the pepper land uses were more compact due to human trampling effects from regular farm works at a localized area. Positive correlations were observed between soil total C and soil total N, soil exchangeable K, soil sum of bases, and soil effective CEC, suggesting that soil total C is the determinant of soil fertility under the agricultural land uses. Meanwhile, insufficient K input in oil palm land uses was observed from the partial nutrient balances estimation. In contrast, P and K did not remain in the soils under pepper land use, although the fertilizers application by the farmers was beyond the crop uptake and removal (harvesting). Because of the siliceous sandy nature (low clay contents) of Spodosols, they are poor in nutrient retention capacity. Hence, maintaining ample supply of organic C is crucial to sustain the productivity and fertility of sandy-textured soils, especially when the litterfall layers covering the E horizon were removed for oil palm and pepper cultivation.

Description: Land use and land cover in the Dano catchment is characterized by a rapid conversion from seminatural vegetation (fallow) to agriculture (cropland). The study compares both the saturated (Ks) and the unsaturated (Kh) hydraulic conductivities under cropland and fallow in the catchment to gain insights into the effect of the current land use on soil water dynamics. Hydraulic conductivity was measured under forty-two (42) pairs of adjacent cropland-fallow plots using a Hood infiltrometer. Ks, Kh, bulk density, and soil texture were further compared using a paired two-tailed Student’s t-test (). The results showed that both Ks and Kh are highly variable irrespective of the land use type (coefficient of variation 〉 100%). The results also showed that Ks was significantly higher (1.16-fold on average) under fallow compared to cropland. As for Kh, the results showed that, from −2 cm to zero tension heads (h), Kh under cropland and fallow is not significantly different; however, as the supplied tension decreases up to the saturation state, Kh under fallow becomes statistically higher compared to cropland. No significant difference was found between soil textures and bulk density under cropland and fallow meaning that the observed differences of Ks and Kh under cropland and fallow were caused by land use and not preexisting difference in texture. These results suggest an increasing risk of erosion, soil fertility reduction, and flood in the catchment because of agricultural land expansion.

Description: The impact of different land-use systems on some soil physicochemical properties and macrofauna abundance in the humid tropics of Cameroon was studied. The land-use types included secondary forest (SF), oil palm plantation (PP), banana plantation (BP), sugarcane plantation (SP), and rubber plantation (RP). Soil particle size distribution, bulk density (BD), pH, organic matter (OM), and number of macrofauna were evaluated. The results showed that OM and number of macrofauna were higher in the SF than in the other land-use types. Pearson’s correlation analysis carried out to determine the relationship between OM and BD showed that OM and BD was strongly negatively related with correlation coefficient of −0.9653. It also showed a strong significant negative correlation between BD and ants population (r = −0.8828) and between soil pH and number of earthworms (r = −0.9072). Based on the results, the SF produced more organic matter and higher number of macrofauna. However, the OM of the other land uses was not low; hence, it could be beneficial to return plant residues to the field for maintaining soil quality.

Description: Multi-soil-layering (MSL) wastewater treatment systems consist of soil units (soil mixture blocks, SMB) arranged in a brick-like pattern surrounded by permeable layers of zeolite or alternating particles of homogeneous sizes that allow for a high hydraulic loading rate. This study evaluated the performances of MSL systems that have been operating for 17 to 20 years in small rural communities. Even though 20 years had passed since this system was installed, high organic matter treatment performance continued. Nitrogen removal was higher than with conventional soil systems. Two of the MSL systems continued to show high phosphorus removal performances, whereas in the third system, the adsorbing capacity was relatively low, requiring further investigation. Treatment performances were largely dependent upon the structure of the MSL systems. It appeared that improving the structure to enhance the contact efficiency between the wastewater and the soil in SMB was important for enhancing treatment performances. The combined use of existing wastewater treatment systems with the MSL system was effective for preventing environmental pollution over a long period.

Description: Discharging of untreated municipal solid wastes (MSWs) onto land is very widespread in developing countries. The compounds contained in MSW cause a harmful effect to human and environment. Hence, an assessment of the extent of their local impact is of great interest to figure out the pollution they cause. Therefore, this study aimed at evaluating the effects of discharge of solid wastes on soil quality within the landfill of Ain-El-Hammam municipality (Algeria). To achieve this, different soil physicochemical parameters were considered: granulometry, electrical conductivity, pH, organic matter content, and heavy metal concentration. The results indicated the influence of the MSW on the physicochemical characteristics of the soil by enhancing the organic matter content of soil (4.53%) and increasing heavy metal content (Cu, Zn, Cd, Pb, Ni, and Cr), which is a clear indication of the level of pollution they are generating.

Description: Histoplasma capsulatum (H. capsulatum) is a thermal-dimorphic fungus, the causal agent of histoplasmosis. Its presence in the environment is related with chicken manure due to their high nitrogen and phosphorus content. In Colombia, chicken manure is the most used raw material in the composting process; however, there is no information about the capacity of H. capsulatum to survive and remain viable in a composted organic fertilizer. To address this question, this study shows three assays based on microbiological culture and the Hc100 nested PCR. First, a composting reactor system was designed to transform organic material under laboratory conditions, and the raw material was inoculated with the fungus. From these reactors, the fungus was not isolated, but its DNA was detected. In the second assay, samples from factories where the DNA of the fungus was previously detected by PCR were analyzed. In the raw material samples, 3 colonies of H. capsulatum were isolated and its DNA was detected. However, after the composting process, neither the fungus was recovered by culture nor DNA was detected. In the third assay, sterilized and nonsterilized organic composted samples were inoculated with H. capsulatum and then evaluated monthly during a year. In both types of samples, the fungus DNA was detected by Hc100 nested PCR during the whole year, but the fungus only grew from sterile samples during the first two months evaluated. In general, the results of the assays showed that H. capsulatum is not able to survive a well-done composting process.

Description: Selecting a suitable physical fractionation method, to investigate soil organic matter dynamics, from the plethora that are available is a difficult task. Using five different physical fractionation methods, on soils either nontreated or with a history of amendment with a range of exogenous organic matter inputs (Irish moss peat; composted horse manure; garden compost) and a resulting range of carbon contents (6.8 to 22.2%), we show that method selection had a significant impact on both the total C recovered and the distribution of the recovered C between unprotected, physically protected, or chemically protected conceptual pools. These between-method differences most likely resulted from the following: (i) variation in the methodological fractions obtained (i.e., distinguishing between aggregate size classes); (ii) their subsequent designation to conceptual pools (e.g., protected versus unprotected); and (iii) the procedures used in sample pretreatment and subsequent aggregate dispersion and fractionation steps. The performance of each method also varied depending on the amendment in question. The findings emphasise the need for an understanding of the nature of the soil samples under investigation, and the stabilisation mechanism of interest, both prior to method selection and when comparing and interpreting findings from literature studies using different fractionation methods.

Description: Flooded ecosystems are conditioned to seasonal floods that promote specific soil conditions, such as low oxygen, hydromorphism, and peculiar chemical reactions. These environments are dependent on flood pulses that determine specific ecological conditions. Ipucas are seasonally flooded discontinuous forest patches that occur exclusively in the Araguaia Plain in Central Brazil. They are located 0.40 to 1.20 m lower than the surrounding plain, which promotes an accumulation of rainwater for five to six months of the year, being entirely or partially dry during the dry season. The aim of this study was to evaluate the horizontal (centre and edge) and vertical (depths: 0–0.20 m and 0.20–0.40 m) variability of physicochemical parameters in Ipucas soils, attempting to establish the importance of flood pulses and the leaching of surrounding areas in soil formation and composition. Samples were collected during the dry season in three Ipucas of similar size and circularity using a Dutch auger. The results reveal that flood pulses promote the deposition of sediments eroded from the surrounding plain, homogenizing the characteristics of the surface soil, from the edge to the centre of the Ipucas. However, biogeochemical processes, also linked to temporary flooding, account for the differences between the surface and deeper soil horizons because anoxic conditions during flooding promote chemical reactions characteristic of anaerobic environments, modifying the pH and organic matter content, in addition to the gleying of soils subjected to flooding, which are then covered by sediments after the dry season. Finally, Ipucas soils are susceptible to anthropic changes and are dependent on seasonal flood pulses.

Description: Land use and land cover in the Dano catchment is characterized by a rapid conversion from seminatural vegetation (fallow) to agriculture (cropland). The study compares both the saturated (Ks) and the unsaturated (Kh) hydraulic conductivities under cropland and fallow in the catchment to gain insights into the effect of the current land use on soil water dynamics. Hydraulic conductivity was measured under forty-two (42) pairs of adjacent cropland-fallow plots using a Hood infiltrometer. Ks, Kh, bulk density, and soil texture were further compared using a paired two-tailed Student’s t-test (p=0.05). The results showed that both Ks and Kh are highly variable irrespective of the land use type (coefficient of variation 〉 100%). The results also showed that Ks was significantly higher (1.16-fold on average) under fallow compared to cropland. As for Kh, the results showed that, from −2 cm to zero tension heads (h), Kh under cropland and fallow is not significantly different; however, as the supplied tension decreases up to the saturation state, Kh under fallow becomes statistically higher compared to cropland. No significant difference was found between soil textures and bulk density under cropland and fallow meaning that the observed differences of Ks and Kh under cropland and fallow were caused by land use and not preexisting difference in texture. These results suggest an increasing risk of erosion, soil fertility reduction, and flood in the catchment because of agricultural land expansion.

Description: Multi-soil-layering (MSL) wastewater treatment systems consist of soil units (soil mixture blocks, SMB) arranged in a brick-like pattern surrounded by permeable layers of zeolite or alternating particles of homogeneous sizes that allow for a high hydraulic loading rate. This study evaluated the performances of MSL systems that have been operating for 17 to 20 years in small rural communities. Even though 20 years had passed since this system was installed, high organic matter treatment performance continued. Nitrogen removal was higher than with conventional soil systems. Two of the MSL systems continued to show high phosphorus removal performances, whereas in the third system, the adsorbing capacity was relatively low, requiring further investigation. Treatment performances were largely dependent upon the structure of the MSL systems. It appeared that improving the structure to enhance the contact efficiency between the wastewater and the soil in SMB was important for enhancing treatment performances. The combined use of existing wastewater treatment systems with the MSL system was effective for preventing environmental pollution over a long period.

Description: Little is known about soil nutrient practice effects on soil moisture under cereal cropping systems. The objective of this research was to evaluate soil moisture content (SMC) response to short-term nitrogen (N) and phosphorus (P) fertilizer rates applied on tef crop varieties and their interactions. A rain-fed fertilizer experiment using tef varieties as the test crop was conducted for two years (2012-2013) in the Chromic Cambisols of northern Ethiopia. The experimental design was laid down in randomized complete block design with three replications. Two treatment factors, namely, fertilizer (four N + P rates) and variety (three tef varieties), were tested. Soil samples were taken at different tef crop growth stages or days after sowing time (DAS) to determine SMC using the gravimetric method. Data were analyzed at a probability level of 0.05. The fertilizer treatments significantly affected the SMC determined at the different tef growth stages and cropping seasons. The highest SMC was determined at 33 DAS (51 m3·m−3), but SMC decreased with increasing fertilizer rates. A higher SMC response to local tef variety than improved variety was found across all the growth stages and cropping seasons. There were also significant differences in SMC among the treatment interactions determined at the different growth stages and across the years. The paired mean differences in SMC due to the treatments between the two years were strongly correlated (r 〉 0.90, P=0.001). For SMC response being effective to fertilizer and its interaction effect with variety, it is suggested that soil management practices that improve moisture such as organic sources should be integrated with the inorganic fertilizer in the conditions of Chromic Cambisols in northern Ethiopia.

Description: Using waste materials from industrial activities to build anthroposols (soils built or altered by humans) can provide soil for reclamation and reduce amounts of materials stored in landfills. Mines and other large industrial disturbances requiring anthroposols usually have large amounts of nonorganic waste materials with low water holding capacity and large amounts of coarse fragments. Thus, water holding capacity is a key property to build into anthroposols as all aspects of revegetation are strongly influenced by soil water content. This research assessed the effectiveness of hydrogel and organic amendments to increase the water retention in common mine wastes used to build anthroposols for reclamation in three greenhouse experiments. Waste materials were crushed rock, lakebed sediment, and processed kimberlite, from a northern diamond mine in Canada. Amendments were hydrogel, sewage, salvaged soil, and peat. Pots were filled with the material and weighed and saturated, followed by periodic weighing until the weight was near constant. Water retention was consistently highest in processed kimberlite, with and without amendments. Water retention increased most with hydrogel in processed kimberlite and crushed rock. Hydrogel application method impacted the initial water retention, but over time, the effect was limited. Water retention in lakebed sediment showed little difference relative to no amendment addition and had lowest increases relative to other substrates. Type of waste material and amendment, application rate, and application method impacted water retention and can be adapted to build anthroposols in the field using waste materials suitable for reclamation.

Description: Selecting a suitable physical fractionation method, to investigate soil organic matter dynamics, from the plethora that are available is a difficult task. Using five different physical fractionation methods, on soils either nontreated or with a history of amendment with a range of exogenous organic matter inputs (Irish moss peat; composted horse manure; garden compost) and a resulting range of carbon contents (6.8 to 22.2%), we show that method selection had a significant impact on both the total C recovered and the distribution of the recovered C between unprotected, physically protected, or chemically protected conceptual pools. These between-method differences most likely resulted from the following: (i) variation in the methodological fractions obtained (i.e., distinguishing between aggregate size classes); (ii) their subsequent designation to conceptual pools (e.g., protected versus unprotected); and (iii) the procedures used in sample pretreatment and subsequent aggregate dispersion and fractionation steps. The performance of each method also varied depending on the amendment in question. The findings emphasise the need for an understanding of the nature of the soil samples under investigation, and the stabilisation mechanism of interest, both prior to method selection and when comparing and interpreting findings from literature studies using different fractionation methods.

Description: Histoplasma capsulatum (H. capsulatum) is a thermal-dimorphic fungus, the causal agent of histoplasmosis. Its presence in the environment is related with chicken manure due to their high nitrogen and phosphorus content. In Colombia, chicken manure is the most used raw material in the composting process; however, there is no information about the capacity of H. capsulatum to survive and remain viable in a composted organic fertilizer. To address this question, this study shows three assays based on microbiological culture and the Hc100 nested PCR. First, a composting reactor system was designed to transform organic material under laboratory conditions, and the raw material was inoculated with the fungus. From these reactors, the fungus was not isolated, but its DNA was detected. In the second assay, samples from factories where the DNA of the fungus was previously detected by PCR were analyzed. In the raw material samples, 3 colonies of H. capsulatum were isolated and its DNA was detected. However, after the composting process, neither the fungus was recovered by culture nor DNA was detected. In the third assay, sterilized and nonsterilized organic composted samples were inoculated with H. capsulatum and then evaluated monthly during a year. In both types of samples, the fungus DNA was detected by Hc100 nested PCR during the whole year, but the fungus only grew from sterile samples during the first two months evaluated. In general, the results of the assays showed that H. capsulatum is not able to survive a well-done composting process.

Description: Mining processes generate waste rock, tailings, and slag that can increase potentially toxic metal (PTM) concentrations in soils. Un-reclaimed, abandoned mine sites are particularly prone to leaching these contaminants, which may accumulate and pose significant environmental and public health concerns. The characterization and spatial delineation of PTMs in soils is vital for risk assessment and soil reclamation. Bumpus Cove, a once active mining district of eastern Tennessee, is home to at least 47 abandoned, un-reclaimed mines, all permanently closed by the 1950s. This study evaluated soil physicochemical properties, determined the spatial extent of PTMs (Zn, Mn, Cu, Pb, and Cd), and examined the influence of soil properties on PTM distribution in Bumpus Cove, TN. Soil samples (n = 52) were collected from a 0.67 km2 study area containing 6 known abandoned Pb, Zn, and Mn mines at the headwaters of Bumpus Cove Creek. Samples were analyzed for Zn, Mn, Cu, Pb, and Cd by microwave-assisted acid digestion and flame atomic absorption spectrometry (FAAS) (12–1,354 mg/kg Zn, 6–2,574 mg/kg Mn, 1–65 mg/kg Cu, 33–2,271 mg/kg Pb, and 7–40 mg/kg Cd). Of the measured PTMs, only Pb exceeds permissible limits in soils. In addition to the PTM analyses, soil physical (texture, moisture content, and bulk density) and chemical (pH, cation exchange capacity (CEC), and total organic carbon (TOC)) properties were evaluated. Spatially weighted multivariate regression models developed for all PTMs using soil physicochemical properties produced improved results over ordinary least squares (OLS) regression models. Models for Zn (R2 = 0.71) and Pb (R2 = 0.69) retained covariates epH, moisture content, and CEC (Zn), and pH and CEC (Pb). This study will help define PTM concentration and transport and provide a reference for state and local entities responsible for contaminant monitoring in Bumpus Cove, TN.

Description: Over the past ten years, more than twenty fires have affected the El Noviciado estate located in Cerro Majuy, Colombia, leading to a loss of soil nutrients and infertility. Lysinibacillus sphaericus, a Gram-positive, mesophilic, and spore-forming bacterium, can be used in soil amendment in the replantation processes, given its ability to fix nitrogen, and nitrify, and solubilize phosphorus, increasing soil nutrients used for plant growth. In this study, we evaluated the soil-amendment potential of L. sphaericus by monitoring the nutrient content of a selected fragment of soil in the El Noviciado estate. For this purpose, we added a mixture of L. sphaericus OT4b.31, OT4b.49, CBAM5, III(3)7, and 2362 strains and determined the ammonium, nitrites, nitrates, phosphorus, and indole acetic acid concentrations in soil. Alnus acuminata sbsp. acuminata, a native model plant known for its restoration effect, was used for replantation. Results indicated that soils with added L. sphaericus presented significant differences in ammonium, nitrites, nitrates, phosphorus, and indole acetic acid concentrations when compared to control soils. Further, results showed no significant differences between soil that had been pre-inoculated in greenhouse and soil directly inoculated in field. We propose that L. sphaericus could be a good nutrient enhancer and plant growth promoter that can be used for the amendment of fire-impacted soils and replantation treatments.

Description: The agricultural use of domestic sewage is a viable alternative for recycling nutrients; however, there is concern regarding the impact of its use due to the concentration of chemical elements present in this type of effluent. The use of principal component analysis determines the existence or lack of anomalous samples and the relations between measured variables and their relative contribution among samples that help in monitoring the impact of the use of effluents on soil chemical components. Thus, the objective of this work was to identify nutrient ions present in the soil solution during the first ratoon sugarcane irrigated with treated domestic sewage applied by subsurface drip irrigation. The experiment was conducted under a randomized block design with 5 treatments and 5 replicates. The treatments were distributed according to the type of water applied in the irrigation system (water surface reservoir and treated domestic sewage), the installation depth of the drip tapes (0.2 or 0.4 m depth), and the treatment without irrigation. By means of soil solution, it was possible to identify an increase in the concentration of salts in the treatments irrigated with treated domestic sewage, which however did not affect the soil quality in the short term. The principal component analysis selected the variables Ca2+, Mg2+, NO3−, K+, and EC as soil solution indicators to monitor areas irrigated with treated domestic sewage.

Description: In soils, dissolved silicon (Si) is adsorbed onto soil particles or is leached into groundwater through the soil profile. Andisols may play an important role in contributing to high dissolved Si concentrations in groundwater on Jeju Island, Korea. In this study, we evaluated the available Si content that potentially affects groundwater composition and investigated the relationship between the available Si content and chemical properties of volcanic ash soil on Jeju Island. We used the 1 M sodium acetate buffer (pH 4.0) to extract the available Si. Selected chemical properties were determined for 290 topsoil samples collected from different land sites throughout Jeju Island, and we analyzed the available Si content in the typifying pedons of Jeju Island and mainland Korea. The available Si content in Jeju Island topsoils ranged from 75 to 150 mg·kg−1, and the available Si content of Andisols in both orchards and grasslands was significantly higher than that of non-Andisols. The available Si content was highly correlated with the amounts of oxalate extractable Si, Al, and Fe in Andisols and was negatively related to the Alp/Alo ratio. With increasing elevation, we detected a decrease in the available Si and allophane content in Andisols, whereas Al-humus complexes increased with increasing elevation. The ratio of available Si in the lowest subsoil/topsoil increased to a value of 6.0, indicating that large amounts of available Si are present in the subsoil. The available Si content in the lowest subsoil of Andisols on Jeju Island was 10 times higher than that in the typifying pedons of the Korean mainland. In contrast, there were no differences in the available Si content between the topsoil and the subsoil of the typifying pedon series of Jeju and mainland non-Andisols because of differences in pedogenic processes. Collectively, our findings indicate that weathering of Andisols on Jeju Island potentially affects the Si concentration in groundwater.

Description: Soil erosion is one of the main forms of land degradation. Erosion contributes to loss of agricultural land productivity and ecological and esthetic values of natural environment, and it impairs the production of safe drinking water and hydroenergy production. Thus, assessment of soil erosion and identifying the lands more prone to erosion are vital for erosion management process. Revised Universal Soil Loss Equation (Rusle) model supported by a GIS system was used to assess the spatial variability of erosion occurring at Kalu Ganga river basin in Sri Lanka. Digital Elevation Model (30 × 30 m), twenty years’ rainfall data measured at 11 rain gauge stations across the basin, land use and soil maps, and published literature were used as inputs to the model. The average annual soil loss in Kalu Ganga river basin varied from 0 to 134 t ha−1 year−1 and mean annual soil loss was estimated at 0.63 t ha−1 year−1. Based on erosion estimates, the basin landscape was divided into four different erosion severity classes: very low, low, moderate, and high. About 1.68% of the areas (4714 ha) in the river basin were identified with moderate to high erosion severity (〉5 t ha−1 year−1) class which urgently need measures to control soil erosion. Lands with moderate to high soil erosion classes were mostly found in Bulathsinghala, Kuruwita, and Rathnapura divisional secretarial divisions. Use of the erosion severity information coupled with basin wide individual RUSLE parameters can help to design the appropriate land use management practices and improved management based on the observations to minimize soil erosion in the basin.

Description: Soil properties contribute to the widely recognised resilience of semiarid areas. However, limited attention has been given in providing a scientific basis of how semiarid soil properties in the various land covers occur and how they influence forage quantity. This study investigated the influence of different soil properties and land cover types on herbaceous biomass quantity in the Karamoja subregion of Uganda. A completely randomized design in three land cover types (thickets and shrublands, woodlands, and savannah grasslands) was implemented. In each vegetation type, 50 × 40 m plots were demarcated with nested plots to facilitate clipping of the herbaceous layer. Composite soil samples at two depths (0–15 cm, 15–30 cm) were obtained from each plot. The results showed that soil properties varied across land cover types. Soil pH ranged between 6.9 and 8.1 and SOM, N, P, and K were generally low in all land cover types. Soil hydraulic properties revealed the existence of rapid to very rapid permeability in thickets/shrublands, grasslands, and woodlands. Percent change in soil properties (0–15 cm to 15–30 cm) was highest in P, Ca, Mg, Na, and SOM. In the grasslands, P positively (p≤0.01) influenced herbaceous biomass, whereas pH, K, Na, % sand, and % clay, N, and SOM had a negative relationship with herbaceous biomass (p≤0.05). Herbaceous biomass in the thickets/shrublands was negatively influenced by P, Ca, and Mg and % clay and positively by N and % silt (p≤0.05). Only N and SOM were significant determinants of herbaceous biomass in the woodlands (p≤0.05). The low level of soil nutrients observed in this study reveals the fragility of semiarid soils, indicating the need for sustainable landscape management.

Description: A study was conducted in the Sabal area, Sarawak, to evaluate the physicochemical properties of sandy-textured soils under smallholder agricultural land uses. Study sites were established under rubber, oil palm, and pepper land uses, in comparison to the adjacent secondary forests. The sandy-textured soils underlain in all agricultural land uses are of Spodosols, based on USDA Soil Taxonomy. The soil properties under secondary forests were strongly acidic with poor nutrient contents. Despite higher bulk density in oil palm farmlands, soil properties in rubber and oil palm land uses showed little variation to those in secondary forests. Conversely, soils under pepper land uses were less acidic with higher nutrient contents at the surface layer, especially P. In addition, soils in the pepper land uses were more compact due to human trampling effects from regular farm works at a localized area. Positive correlations were observed between soil total C and soil total N, soil exchangeable K, soil sum of bases, and soil effective CEC, suggesting that soil total C is the determinant of soil fertility under the agricultural land uses. Meanwhile, insufficient K input in oil palm land uses was observed from the partial nutrient balances estimation. In contrast, P and K did not remain in the soils under pepper land use, although the fertilizers application by the farmers was beyond the crop uptake and removal (harvesting). Because of the siliceous sandy nature (low clay contents) of Spodosols, they are poor in nutrient retention capacity. Hence, maintaining ample supply of organic C is crucial to sustain the productivity and fertility of sandy-textured soils, especially when the litterfall layers covering the E horizon were removed for oil palm and pepper cultivation.

Description: In the natural environment, soil pH has an enormous influence on soil biogeochemical processes. Soil pH is, therefore, described as the “master soil variable” that influences myriads of soil biological, chemical, and physical properties and processes that affect plant growth and biomass yield. This paper discusses how soil pH affects processes that are interlinked with the biological, geological, and chemical aspects of the soil environment as well as how these processes, through anthropogenic interventions, induce changes in soil pH. Unlike traditional discussions on the various causes of soil pH, particularly soil acidification, this paper focuses on relationships and effects as far as soil biogeochemistry is concerned. Firstly, the effects of soil pH on substance availability, mobility, and soil biological processes are discussed followed by the biogenic regulation of soil pH. It is concluded that soil pH can broadly be applied in two broad areas, i.e., nutrient cycling and plant nutrition and soil remediation (bioremediation and physicochemical remediation).

Description: Crop rotation systems especially dominated by cereals (maize and wheat) are intimately linked to soil properties. The objective of the study was to investigate the effect of crop rotations and conservation practice on selected soil physicochemical properties in northwestern part of Ethiopia. Soil samples (0–20 cm depth) were collected from seven crop rotations with conservation practice and adjacent fields without any conservation measure in three replications. A total of forty-two composite samples were used for analysis by using SAS software. The land rotated with maize-wheat-faba bean exhibited significantly higher mean bulk density (1.06 g/cm3) than the land rotated with other crops (i.e., ranging from 1.02 to 1.04 g/cm3). Mean values of pH (5.34, 4.98, and 5.4), Ex. acidity (2.03, 2.53, and 2.16 cmolc/kg), soil OM (4.53%, 5.12%, and 5.02%), CEC (45.17, 48.03, and 49.47 cmolc/kg), TN (0.23, 0.25, and 0.27%), Av.P (10.21, 7.23, and 7.95 ppm), and C : N ratio (11.18, 11.95, and 10.8) were recorded under rotations with continuous maize, maize-pepper-pepper, and maize-faba bean-pepper, respectively. Mean values of pH (5.34 and 4.97), Av.P (9.51 and 6.53 ppm), CEC (48.3 and 46.87 cmolc/kg), and Ex. acidity (2.5 and 2.85 cmolc/kg) were also recorded under conserved and unconserved farmlands, respectively. Considering the interaction effect of crop rotations by conservation practice, all studied parameters, except bulk density, CEC, and C : N ratio, were significantly (p

Description: Land degradation caused by improper land use management is a critical worldwide problem that has revived the issue of resources sustainability. Soil degradation, which involves physical, chemical, and biological degradation, is the key component of land degradation. Assessment of soil quality (SQ) indicators that distinguish soil degradation in different land use (LU) types is enviable to achieve sustainable land management strategies. The objective of this study was to assess the effects of land uses on soil quality indicators in the Geshy subcatchment of the Gojeb River Catchment, Omo-Gibe Basin, Ethiopia. The LU types identified for evaluation included natural forest, cultivation, and grazing lands. Accordingly, a total of 54 soil samples (three LU types × three slope classes (blocks) × three replications × two soil depths) were collected with an “X” plot design for data analysis. Statistical differences in SQ indicators were analyzed among LU types, slope classes, and soil depths and tested using univariate analysis of variance and Pearson’s correlation coefficient, following the general linear model. The results showed that a number of SQ indicators were significantly influenced by LU changes and soil depths. The sand, dry soil bulk density ρb, volumetric soil water contents (VSWC), total porosity, water infiltration rates, cumulative infiltration, and total nitrogen showed significant variations between the natural forest and the other LU types and soil depths (p0.05). The overall qualities of the soils under the cultivation land were inferior in VSWC, TP, water infiltration rates, SOC contents, and TN soil attributes of the adjacent natural forest and grazing lands. The studied soils were found to be dominantly of clays with slightly acidic and low SOC contents and slow in their infiltration rate. Thus, integrated and sustainable land management, aimed at enhancing proper LU systems, is crucial for the sustainable ecosystem functioning and is the most effective way in reversing of soil quality deterioration.

Description: The impact of different land-use systems on some soil physicochemical properties and macrofauna abundance in the humid tropics of Cameroon was studied. The land-use types included secondary forest (SF), oil palm plantation (PP), banana plantation (BP), sugarcane plantation (SP), and rubber plantation (RP). Soil particle size distribution, bulk density (BD), pH, organic matter (OM), and number of macrofauna were evaluated. The results showed that OM and number of macrofauna were higher in the SF than in the other land-use types. Pearson’s correlation analysis carried out to determine the relationship between OM and BD showed that OM and BD was strongly negatively related with correlation coefficient of −0.9653. It also showed a strong significant negative correlation between BD and ants population (r = −0.8828) and between soil pH and number of earthworms (r = −0.9072). Based on the results, the SF produced more organic matter and higher number of macrofauna. However, the OM of the other land uses was not low; hence, it could be beneficial to return plant residues to the field for maintaining soil quality.

Description: Discharging of untreated municipal solid wastes (MSWs) onto land is very widespread in developing countries. The compounds contained in MSW cause a harmful effect to human and environment. Hence, an assessment of the extent of their local impact is of great interest to figure out the pollution they cause. Therefore, this study aimed at evaluating the effects of discharge of solid wastes on soil quality within the landfill of Ain-El-Hammam municipality (Algeria). To achieve this, different soil physicochemical parameters were considered: granulometry, electrical conductivity, pH, organic matter content, and heavy metal concentration. The results indicated the influence of the MSW on the physicochemical characteristics of the soil by enhancing the organic matter content of soil (4.53%) and increasing heavy metal content (Cu, Zn, Cd, Pb, Ni, and Cr), which is a clear indication of the level of pollution they are generating.

Description: The clay layers at hilly regions in the study area were very thick. The presence of very thick clay caused several difficulties in terms of environmental management, particularly in reducing georisk due to landslide. However, initial observations proved that areas of active landslides had better vegetation cover. The objective of this study was to find out ecological roles of landslides in livelihood in the Middle Bogowonto Watershed. The ecological roles of landslide were examined through field empirical evidences. Texture, bulk density, permeability, structure, and index plasticity were conducted for analyses of soil physical properties. Stepwise interpretation was made using 1 : 100,000–1 : 25,000 Indonesian topographic maps and remote sensing images of 30 m–

Description: The conversion of natural lands into agricultural lands can lead to changes in the soil microbial community structure which, in turn, can affect soil functions. However, few studies have examined the effect of land use changes on the soil microbial community structure in sub-Saharan Africa. Therefore, the aim of this research was to investigate the relationships among soil characteristics and microbial communities in natural and agricultural ecosystems in a semideveloped lowland farm in the central region of Zambia, within which small-scale wetlands had been partly developed as watermelon (Citrullus lanatus) and/or maize (Zea mays) farms. We sampled soils from four different land use types within this farm: “native forest,” “grassland,” “watermelon farm,” and “maize farm.” We found that the land use type had a significant effect on the soil bacterial community structure at the class level, with the class Bacilli having significantly higher relative abundances in the forest sites and Gammaproteobacteria having significantly higher relative abundances in the maize sites than in the other land use types. These findings indicate that these bacterial classes may be sensitive to changes in soil ecosystems, and so further studies are required to investigate microbial indicators for the sustainable development of wetlands in sub-Saharan Africa.

Description: The emission of greenhouse gases (GHGs) results in global warming and climate change. The extent to which developing countries contribute to GHG emissions is not well known. This study reports findings on the effects of different land-use systems on GHG emissions (CO2 in this case) from two locations in the southern zone of Ghana, West Africa. Site one (located at Kpong) contained a heavy clay soil while site two (located at Legon) contained a light-textured sandy soil. Land-use systems include cattle kraals, natural forests, cultivated maize fields, and rice paddy fields at site one, and natural forest, woodlots, and cultivated soya bean fields at site two. CO2 emissions were measured using the gas entrapment method (PVC chambers). Trapping solutions were changed every 12–48 h and measurement lasted 9 to 15 days depending on the site. We found that, for the same land-use, CO2 emissions were higher on the clay soil (Kpong) than the sandy soil (Legon). In the clay soil environment, the highest average CO2 emission was observed from the cattle kraal (256.7 mg·m−2·h−1), followed by the forest (146.0 mg·m−2·h−1) and rice paddy (140.6 mg·m−2·h−1) field. The lowest average emission was observed for maize cropped land (112.0 mg·m−2·h−1). In the sandy soil environment, the highest average CO2 emission was observed from soya cropped land (52.5 mg·m−2·h−1), followed by the forest (47.4 mg·m−2·h−1) and woodlot (33.7 mg·m−2·h−1). Several factors influenced CO2 emissions from the different land-use systems. These include the inherent properties of the soils such as texture, temperature, and moisture content, which influenced CO2 production through their effect on soil microbial activity and root respiration. Practices that reduce CO2 emissions are likely to promote carbon sequestration, which will consequently maintain or increase crop productivity and thereby improve global or regional food security.

Description: Anthropogenic activities have greatly increased heavy metal pollution worldwide. Due to inadequate waste management, mining is one of the chief causes. One particularly affected area in Mexico is the “La Zacatecana” Lagoon, in the municipality of Guadalupe, Zacatecas. From colonial times until the mid-nineteenth century, about 20 million tons of mine tailings were deposited at this site. Here, we catalogue the heavy metal content and their distribution in soils and sediments of La Zacatecana. The mobility of lead in soils was also assayed by sequential extraction. Concentrations of the different metals analysed were as follows: Pb 〉 Cr 〉 As 〉 Ni 〉 Hg 〉 Cd. Site VIII accumulated the highest amount of Pb (3070 mg·kg−1) sevenfold more than the limit established by the Mexican standards for agricultural soils (i.e., 400 mg·kg−1). On the other hand, the contents of Cd, Cr, and Ni were within the levels accepted by the above normativity, set at 37, 280, and 1600 mg·kg−1, respectively. Concentrations of Hg and Pb were highest in the north-northwest zone of the lagoon and decreased towards the southeast. Except for Site VIII where 30% of the Pb was in an interchangeable form or bound to carbonates, most Pb in La Zacatecana soils was present in an unavailable form, associated with Fe-Mn oxides.

Description: Humification is considered to be a global process that is implemented in soils and organic sediments and also in natural water and air. The term “suspended soils” has become increasingly common in recent years. Suspended soils are defined as the part of the organic matter that has not undergone the full decomposition process and has not turned into the humus of terrestrial soils. Suspended soils were shown to contain higher total nitrogen, phosphorus, and potassium contents than the forest soil, but the moisture content in suspended soils was significantly lower. Our study of the structural composition of humic substances in suspended soils was conducted with an aim of evaluating the humification rates and structural composition of humic acids in the suspended soil in tropical forests of South Vietnam. Soil samples from three selected areas were investigated: the soil under phorophytes (mineral soil presented by samples of topsoil of the typical dry savanna landscape) and two soils from epiphytous formations. Samples were collected from savanna-type sparse communities, located on oligotrophous plains in Phú Quốc Island (South Vietnam) in 2015. General properties of the soil and the elemental composition of suspended soils were determined, and the humic substance chemical composition was evaluated using solid state 13C-NMR. Data obtained showed that the pH of the soils under phorophytes was higher than in the suspended soils; basal respiration did not tend to change indices between soils under phorophytes and suspended soils, but the suspended soil was less enriched by nitrogen than the soil under phorophytes. This can be related to the total amount of organic matter exposed to humification in various soils and to the presence of an essential portion of mineral particles in the soil under phorophytes. Data on elemental composition of the humic acids (HAs) indicated that one method of humification is implemented in all three soils that were investigated. The humic acids of the phorophyte soil showed the same content of aromatic fraction as the suspended soil. The most comparable soil type in terms of humic substance composition is Cambisols from humid forests of subboreal and subtropical zones. The humification process implemented in suspended soils showed the absence of mineral compounds or mineral fine earth, which indicated that humification in conditions of pure organic substrates can result in formation of deep humified organic matter, as shown by humic acids with an essential aromatic fraction content.

Description: Soil moisture-holding capacity data are required in modelling agrohydrological functions of dry subhumid environments for sustainable crop yields. However, they are hardly sufficient and costly to measure. Mathematical models called pedotransfer functions (PTFs) that use soil physicochemical properties as inputs to estimate soil moisture-holding capacity are an attractive alternative but limited by specificity to pedoenvironments and regression methods. This study explored the support vector machines method in the development of PTFs (SVR-PTFs) for dry subhumid tropics. Comparison with the multiple linear regression method (MLR-PTFs) was done using a soil dataset containing 296 samples of measured moisture content and soil physicochemical properties. Developed SVR-PTFs have a tendency to underestimate moisture content with the root-mean-square error between 0.037 and 0.042 cm3·cm−3 and coefficients of determination (R2) between 56.2% and 67.9%. The SVR-PTFs were marginally better than MLR-PTFs and had better accuracy than published SVR-PTFs. It is held that the adoption of the linear kernel in the calibration process of SVR-PTFs influenced their performance.

Description: The area of Nylon represents a sensible and vulnerable environment where water erosion is the cause of many soil losses contributing to the production and movement of sediments from the upstream to the lowest depths. The high level of rainfall in this town, soil texture (sand-clay-silt), and the anarchic occupation of the area play a part in the important deterioration of the bare ground on the upstream of the catchment area. This causes with time an instability of structures and living places which can lead to their progressive disappearance. In order to assess the quantities of displaced sediments, the studies on the quantification of soil moved annually by water erosion are carried out. A direct method is used consisting in using a minisimulator of rain (NEME) in order to understand the phenomena involved and assess the quantity of sediments which can be moved. It helps in assessing erosion caused by the rain and extrapolating results over the catchment area of the chosen field of study. USLE relation has permit to make an extrapolation of the quantity of soil affected, and the result shows that the average potential of loss of soil is 153.57 t/ha/annum.

Description: Kenya’s tea industry depends predominantly on imported compound NPK fertilizers to replenish nutrients removed through plucking. These fertilizers cannot be easily manipulated for specific soils and tea clones. They also frequently become hazardous within tea-growing environments. In this respect, two fertilizer blends containing NPKS 25 : 5 : 5 : 4 + 9Ca + 2.62Mg and NPKS 23 : 5 : 5 : 4 + 10Ca + 3Mg with trace elements have been produced commercially in the country. However, the extent to which the blended fertilizers may contribute to optimal economic gains without degrading the environment has not been determined. This was the knowledge gap that this study seeks to address. The goal of this study was to evaluate the economic efficacy of fertilizer blends with the aim of identifying optimal levels of application which would maximize tea productivity with minimal negative impacts on the environment. The study hypothesized that blended fertilizers maximize productivity of tea clones with minimal environmental damage. The fertilizer blends were evaluated in two study sites, i.e., Timbilil Estate in Kericho and Kagochi farm in Nyeri. The sites were selected purposefully, one in the eastern and the other in the western tea-growing areas. The trial was laid out in randomized complete block design with two fertilizer blends and the standard NPK 26 : 5 : 5 as control. The treatments were applied at four fertilizer rates (0 (control), 75, 150, and 225 kg·N·ha−1·yr−1), replicated thrice. Leaf samples were collected and analyzed for nutrient uptake as well as associated yields and economic trends. The economic optimum nitrogen rate (EONR) was achieved at 75 kg·N·ha−1·yr−1 at Kagochi with all fertilizers, while at Timbilil, EONR was variable, between 75 and 225 kg·N·ha−1·yr−1 with fertilizer types. This study has shown that, based on the economic point of view, Blend “A” was the most efficient and consistent fertilizer in production and economic returns across the two sites.

Description: This study examined the abundance of bacteria and nirS-type denitrifiers associated with the rhizospheres of three emergent macrophyte species (Juncus effusus, Typha latifolia, and Peltandra virginica) to gain a greater understanding of plant-microbe interactions in wetland soils. Sampling of plant and soil properties was performed during the growing season (June) and following plant senescence (November) at two tidal freshwater wetlands. Quantitative polymerase chain reaction was used to determine the abundance of bacteria (16S rRNA) and nirS-type denitrifier genes from the rhizosphere and rhizoplane of each plant species and from nearby unvegetated soils. For bacteria, there was a positive rhizosphere effect that did not differ significantly across plant species. In contrast, significant differences in the abundance of nirS-type denitrifiers were observed across the plant species. Rhizosphere abundance was ∼2-fold greater in Peltandra virginica and 4-fold greater in Typha latifolia compared to Juncus effusus. For both bacteria and nirS-type denitrifiers, plant effects were greater during the growing season, and abundance was highly correlated with soil pH, moisture, and organic matter content. Overall, these results demonstrate plant effects on the rhizosphere microbial community can be species‐specific and that there is a synergistic relationship between plant species and environmental conditions.

Description: Aquifer protective capacity and groundwater quality investigations around some open dumpsites were conducted along New Road Sapele, Delta State. Nine Schlumberger arrangements of vertical electrical soundings (VES) were carried out with a maximum electrode separation of 500 m, and obtained data were interpreted by partial curve matching and computer iteration using Win Resist software. 2D survey using nine dipole-dipole stations was also utilized to give resistivity map of the dumpsites, while standard laboratory methods were used to analyze the groundwater. The study shows four to five geoelectric sections. The aquifer is within the third, fourth, and fifth layers at a depth of 30 m. The overburden protective capacity from the total longitudinal unit conductance indicates that VES 1 and 5 are adequately protected with protective capacity of 0.7 to 0.9 mhos, VES 2, 3, 6, and 7 are moderately protected with conductance values of 0.2 to 0.69 mhos, VES 4 is weakly protected with values of 0.12 mhos, and VES 8 and 9 are poorly protected with values of 0.003 to 0.004 mhos. In the 2D imaging, VES 4, 8, and 9 show contaminant presence to the depth of 20 m while VES 3, 6, and 7 show contamination to a depth of 50 m. However, the aquifer shows good transmissivity, an indication that if it is contaminated, the contaminants will circulate the aquifer at a high rate. The groundwater flows in the northeast (NE) direction, thereby recharging river Ethiope. The study also shows the presence of lead (0.01 mg/l), nickel (0.02 mg/l), and cadmium (0.03 mg/l), which made it unsafe for drinking and use in other life-related activities. Groundwater should hence be sourced from a depth of about 45–50 m in order to tap from the uncontaminated aquifer.