ALBERT

Description: The distribution of lipid S (sulpholipids) in 27 soils was examined in relation to factors which influence its abundance in different soil environments. Lipid S was found in all soils examined, but at levels varying from 1.6 to 291 ppm S. Lipid S content was higher in organic horizons than in mineral horizons, and poorly drained soils had higher lipid S than freely drained soils. Highest levels were observed in poorly drained organic soils. Lipid S accounted for a small proportion of total S (0.5–3.5%) and of total lipid (0.03–1.7%). Lipid S levels were on average three times higher than lipid P. Lipid S was significantly correlated with total S, HI-reducible S and organic C. In a regression analysis, 89% of the variation in soil content of lipid S was accounted for by total lipid and total S contents. The distribution of total lipids confirmed previous reports that higher levels were associated with soils having restricted biological activity.

Description: Interest in composting as a means of handling the large volumes of manure generated by southern Alberta beef cattle feedlots has increased in recent years. We measured concentrations of 19 elements (C, N, P, Na, Ca, Mg, K, S, Al, Fe, Mn, Zn, Cu, Cr, Ni, P b , Co, Mo and Cd) in fresh manure, interim-composted manure and finished compost, at four commercial feedlots. Thirteen elements showed increased concentrations (by 26–73%) with composting, while four (C, Cr, Ni and Mo) showed concentration declines. Of the remaining two, the trend in N concentration was feedlot dependent, while Pb was largely unaffected. Total mass loss during composting averaged 54%, which represents a substantial decrease in haulage requirements. Overall average C losses were 61% and N losses 33%. On an equivalent wet weight basis ("as-is"), composting allowed haulage of 56% more N, 84% more P, 91% more Zn, and 76% more Cu than fresh manure, which is advantageous in terms of moving nutrients and trace elements from high to low-loading areas. Our study quantifies nutrient and trace element behaviour during composting, provides comparative data with fresh manure, and helps tailor end-use decisions (e.g., haulage distance, application rate) on the compost product. Key words: Manure, compost, beef cattle feedlots, nutrients, trace elements

Description: The morphological expression of podzolization in four Humo-Ferric Podzols increased in a northerly direction over a distance of approximately 74 km from the north shore of Lake Huron. The transect coincided with changes in both geology and vegetation. All the soils were developed in coarse-textured acid tills whose composition was not significantly different to explain the observed variations in soil morphology. Using quartz as an internal standard, the order of mobility from surface horizons was found to be Mg 〉 Fe = Ca 〉 Na = Al 〉 K 〉 Ti. Pyroxenes, amphiboles, chlorite and albite were the most easily weathered minerals. Protocatechuic, p-coumaric, gentisic and gallic acids were found to be the major phenolic acids in water extracts of soil surface horizons. The content of both phenolic acids and carbohydrates in surface horizons increased as the morphological expression of podzolization increased.

Description: Soils cultivated for 60 yr were compared with uncultivated forested soils at 10 sites in Appalachian Quebec. All soils belonged to the Humo-Ferric Podzol Great Group, five sets of comparisons being located on the Ascot soil series and five on the Greensboro. Comparisons were made between corresponding soil horizons, analytical data being derived from the bulking and analysis of six sample cores per horizon. Cultivation increased weight of soil in the solum and in the whole profile of both the Greensboro and the two soil series combined; bulk density was slightly affected. Field capacity, permanent wilting point and available water of the surface and sub-surface layers, in the solum and in the whole profile, were significantly increased by cultivation. The increase of available water was accompanied by a corresponding decrease in gravitational water. The content fine clay was significantly decreased in the surface layer and in the solum, while it was increased significantly in the C horizon by cultivation which also decreased the acidity of the surface and sub-surface in both series. There was a marked increase in organic matter content, but the level of fulvic acid was relatively unaffected by cultivation, indicating that the increased H/F ratio was primarily due to an increase in humic acid. Generally, Al content was not significantly changed, while significant increases in Fe and Mn were observed in the surface and solum of cultivated profiles. A deduction is made that cultivation has regraded podzol profiles into Dystric Brunisol ones which have started to evolve already toward kinds of Luvisolic profiles.

Description: The variability of forest floor properties over short distances and the number of samples required to achieve desired levels of precision for estimation of property means have received little attention. The importance of the forest floor for forest management is well known and increasingly forest floor characteristics are being used to classify forest sites. Highly variable forest floor properties require more intensive sampling and often have less predictive value for characterization and classification purposes. A study site at Port Hardy was used to characterize forest floors for selected physical and chemical properties. The three sites chosen represented xeric, mesic and hygric positions along a hygrotopic gradient. A stratified random sampling procedure was used to obtain 15 samples at each site. Fifteen samples were adequate to characterize the means at 10% allowable error with a 95% confidence level for total nitrogen, organic carbon, pH and cation exchange capacity. Greater than 15 samples were required for exchangeable bases and forest floor thickness for the same level of accuracy and confidence. Even at 25% allowable error and 90% confidence, 40 samples and 16 samples, respectively, were required for exchangeable Ca and Mg.

Description: It is recognized that volatilized ammonia (NH3) from intensive livestock production can be a significant pathway for nitrogen (N) pollution to land and water, and can contribute to poor air quality. The objectives of our study were to document NH3 emissions from a dairy lagoon and to assess the influence of meteorology on NH3 emissions. Ammonia emissions were determined using a backward Lagrangian Stochastic approach using WindTrax software, an open-path NH3 laser and a sonic anemometer. Results indicate that an average 5.1 ± 1.6 g NH3 m-2 d-1 was released over the summer; however, the emission varied typically over 24 h between 3.6 and 8.6 g NH3 m-2 d-1. Wind speed and surface temperature of the lagoon had similar influences on the magnitude of the release, where their direct impact on NH3 emission accounted for 28 and 31% of the variability, respectively. The main implication of this study is that NH3 losses are significant from dairy lagoons, contributing to the issue of N pollution. As well, NH3 emissions are a loss of valuable N for manure used as fertilizer, which in our study amounted to approximately 13% of the total ammoniacal N content of the manure in the lagoon. Key words: Ammonia, dairy, manure, cattle, dispersion model

Description: Intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. & D.R. Dewey subsp. intermedium] is a productive, high-quality perennial forage that lacks persistence under grazing. A study was conducted to evaluate the effects of three grazing times on soil bulk density, soil pH, and soil organic C under intermediate wheatgrass. Treatment effects on the three soil attributes were negligible, implying grazing time did not negatively impact intermediate wheatgrass beyond a threshold whereby critical soil functions were impaired. Findings from this study are important in the context of sustainable forage and cropping system management, where maintaining or improving critical soil functions are essential for enhancing agroecosystem sustainability. Key words: Seeded perennial forages, Northern Great Plains, soil organic C

Description: Hydrological models require the determination of fitting parameters that are tedious and time consuming to acquire. A rapid alternative method of estimating the fitting parameters is to use pedotransfer functions. This paper proposes a reliable method to estimate soil moisture at -33 and -1500 kPa from soil texture and bulk density. This method reduces the saturated moisture content by multiplying it with two non-linear functions depending on sand and clay contents. The novel pedotransfer function has no restrictions on the range of the texture predictors and gives reasonable predictions for soils with bulk density that varies from 0.25 to 2.16 g cm-3. These pedotransfer functions require only five parameters for each pressure head. It is generally accepted that the introduction of organic matter as a predictor improves the outcomes; however it was found by using a porosity based pedotransfer model, using organic matter as a predictor only modestly improves the accuracy. The model was developed employing 18 559 samples from the IGBP-DIS soil data set for pedotransfer function development (Data and Information System of the International Geosphere Biosphere Programme) database that embodies all major soils across the United States of America. The function is reliable and performs well for a wide range of soils occurring in very dry to very wet climates. Climatical grouping of the IGBP-DIS soils was proposed (aquic, tropical, cryic, aridic), but the results show that only tropical soils require specific grouping. Among many other different non-climatical soil groups tested, only humic and vitric soils were found to require specific grouping. The reliability of the pedotransfer function was further demonstrated with an independent database from Northern Italy having heterogeneous soils, and was found to be comparable or better than the accuracy of other pedotransfer functions found in the literature. Key words: Pedotransfer functions, soil moisture, soil texture, bulk density, organic matter, grouping

Description: Adequate nitrogen (N) fertilization is crucial to optimize yield and quality of potato and also to minimize N environmental losses. Effects of rates and timing of N fertilizer on residual soil nitrate (RSN) [NO3-N, 0-0.7 m], soil solution nitrate (SWN) concentrations and apparent fertilizer nitrogen recovery (Nrec) by potato (Solanum tuberosum L.) tubers were evaluated from 1999 to 2001. Two sites representative of the management zones (MZ) previously delineated by apparent soil electrical conductivity and differing in soil water availability were selected. The MZ differed primarily with depth to a clayey substratum, with average values of 1.06 m and 1.34 m in the shallow MZ (SMZ) and in the deep MZ (DMZ), respectively. At each site, a trial with 21 treatments including five rates of ammonium nitrate (0–200 kg N ha-1 in 1999; 0–240 kg N ha-1 in 2000 and 2001) was conducted. Each N rate was applied according to five application timings (100, 75, 50, 25 or 0% of N applied at planting with the remainder at hilling). The effects of N rates and timing on Nrec, RSN and SWN sometimes differed between sites. The Nrec was less responsive to N rates and timing in the SMZ site compared with the DMZ site. Application of the same rate of fertilizer N generally resulted in higher values of RSN at harvest in the SMZ site compared with the DMZ site. Measured SWN was higher in the DMZ than in the SMZ on several occasions in 1999 and 2001, indicating greater nitrate (NO3) leaching in the DMZ site compared with the SMZ site. Different site-specific N management regimes could thus be used at the two sites to improve N use efficiency and to limit the risk of NO3 leaching. However, the temporal variability in the measured parameters, influenced mainly by climatic conditions, was greater than the spatial N variability and this emphasizes the fact that a dynamic model of the N status based on the soil and/or the plant is a prerequisite to help growers to adjust the N fertilizer application within fields and seasons. Key words: Solanum tuberosum, apparent soil electrical conductivity, suction lysimeter

Description: The overall objective of this study was to measure the major nitrogen pools and fluxes in nutrient- and peat-rich, vegetated marshes and fens surrounding shallow ponds in the Western Boreal Plain (WBP) of Canada. Within the same peatland-pond complex, marshes and fens did not differ from each other in major N fluxes and pool sizes; however, significant differences in N dynamics were measured between different peatland-ponds. Specifically, N cycling rates (gross and net mineralization) were much greater in a floating peatland than in a non-floating peatland. Gross N mineralization rates were 59 and 453 mg N m-2 d-1 in the non-floating and floating peatlands, respectively. Gross ammonification rates were approximately 4–10 times net rates while gross nitrification rates were 500–800 times net rates, indicating rapid turnover of extractable inorganic N pools. Increased moisture and carbon in the floating peat supported higher microbial biomass and activity, however net primary production values were lower, presumably due to competition by microbes for available inorganic N. Monthly measurements of N fluxes were combined to provide an estimate of annual internal N cycling within marshes and fens surrounding shallow ponds in the WBP. Key words: Gross mineralization, microbial biomass, nitrogen, peatland

Description: Organic matter with high C:N ratios accumulated on mineral soil retards cycling of nutrients in semi-mature jack pine (Pinus banksiana Lamb.) ecosystems. To test whether N as ammonium sulfate or as urea stimulates organic matter decomposition, 200 kg N∙ha−1 were applied to mixed L and F horizon material in Warburg respirometer flasks. Soils were incubated at 13 °C and constant 0.3 bar (340%) moisture; O2 consumption was measured as an index of microbial activity. In urea-treated soil, O2 uptake was much higher than with unamended soil over a 7-wk incubation period, and this indicated a marked effect of urea on microbial activity. The fact that ammonium sulfate depressed respiration rates was evidence that stimulation of microbial respiration by urea was not initially related to added N, but rather to an increase in soil-soluble C resulting from soil pH changes during hydrolysis. In the presence of a C source (ethanol), a 5-fold increase in respiration was noted, whereas C and urea together produced a 15-fold increase in activity. These results suggest that readily available energy for microbial growth, rather than N, limits the initial decomposition of L and F materials in this pine stand. Once microbial demand for C is satisfied, a further increase in microbial activity is produced by N addition.

Description: From the solubility equilibrium data of basic aluminite at three temperatures, the standard free energy change (ΔG°), enthalpy change (ΔH°), and entropy change (ΔS°) were determined as 160.02 kcal∙mole−1, 65.48 kcal∙mole−1 and 317.1 cal∙deg−1]mole−1, respectively. From these values the free energy of formation (ΔGf°) and the heat of formation (ΔHf°) of basic aluminite was also computed and was 1465.25 kcal∙mole−1 and 1682.08 kcal∙mole−1, respectively.

Description: Regression and covariance analysis of a 13-yr rotation experiment of corn on Brookston clay soil showed that grain yield of corn could be related to each of nine other plant and soil measurements. Soil compaction as measured by bulk density was negatively associated with the level of leaf K in the plants, as well as available soil moisture. The major part of the yield difference between fertilized continuous corn and fertilized corn following alfalfa could be accounted for by multiple regression of grain yield on leaf N and K nutrient levels, soil compaction and soil moisture. Soil compaction was not affected or modified by fertilizer treatment. Response of corn grain yield to soil conditions, moisture and plant nutrient level appears to vary with rotation and fertilizer input.

Description: The dynamics of fixation and release of NH4+ in soils were studied using tracer N under field and laboratory conditions. Field data showed that release of fixed NH4+ was relatively slow after an initial moderately fast release. Forty months of field weathering of Bainsville soil left 3.48 kg 15N/ha in the 75-cm profile of the 13.5 kg 15N/ha applied and most (76%) of this recovered 15N was fixed NH4+–N. The relative quantitative importance of recently fixed NH4+ in the various particle size fractions was not in the same order as the native fixed NH4+. The fine silt fraction (2–5 μm) fixed a larger amount (whole soil basis) than the fine clay fraction (

Description: Volumetric water content (θv) was estimated from time domain reflectometry (TDR) measurementsof apparent dielectric permittivity (Ka) in an organic soil (Humisol). The goals of this study were: (i) to test the accuracy of existing θv-Ka relationships in this soil and if found insufficient (ii) to develop alternative θv-Ka relationships for this organic soil. The Ka values were measured over a wide range of θv in intact soil cores taken from three horizons (Ohp, Of, Oco). Empirical θv-Ka relationships found in the literature for organic porous media could not accurately describe the θv-Ka relationships of any horizon of this Humisol, probably because of the its very large organic matter content (〉 75%) of this soil. New θv-Ka relationships for each horizon were consequently developed. Key words: Organic soil, TDR, coprogenic soil, volumetric water content, apparent dielectric permittivity

Description: Ridge-tilled corn (Zea mays L.) could benefit from arbuscular mycorrhizal (AM) fungi. Under low soil disturbance, AM hyphal networks are preserved and can contribute to corn nutrition. A 2-yr study was conducted in the St. Lawrence Lowlands (Quebec, Canada) to test the effects of indigenous AM fungi on corn P nutrition, growth, and soil P in field cropped for 8 yr under ridge-tillage. Phosphorus treatments (0, 17, 35 kg P ha-1) were applied to AM-inhibited (AMI) (fungicide treated) and AM non-inhibited (AMNI) plots. Plant tissue and soil were sampled 22, 48 and 72 days after seeding (DAS). P dynamics was monitored in situ with anionic exchange membranes (PAEM) from seeding to the end of July. AMNI plants showed extensive AM colonization at all P rates. At 22 DAS, AMI plants had decreased growth in the absence of P inputs, while AMNI plants had higher dry mass (DM) and P uptake in unfertilized plots. The PAEM was lower in the AMNI unfertilized soils in 1998 and at all P rates in 1999, indicating an inverse relationship between P uptake and PAEM. At harvest, grain P content of AMNI plants was greater than that of AMI plants. In 1998, only AMI plants had decreased yield in the absence of P fertilization. In 1999, AMNI plants produced greater grain yield than AMI plants at all P rates. AM fungi improve the exploitation of soil P by corn thereby maintaining high yields while reducing crop reliance on P inputs in RT. Key words: Arbuscular mycorrhizae, ridge-tillage, soil P dynamics, corn, P nutrition

Description: The sustainability of organic dairying in Canada, with respect to nutrients, remains unexamined. To assess how management affects nutrient status, we documented whole farm nutrient (NPK) budgets over 2 yr (2003 to 2005) and soil (0 to 15 cm) P and K status on 15 long-term Ontario organic dairy farms. Farm size, livestock density and herd productivity averaged 110 ha, 1.00 livestock units ha-1 and 5656 kg milk cow-1 yr-1, respectively. Annual farm nutrient surpluses of 75 (N), 1 (P) and 11 (K) kg ha-1 yr-1 were lower than those reported for confinement-based dairy farms in the United States, pointing to possible environmental benefits from reduced off farm impacts on air and water quality. Weighted average soil test P levels were low (〈 10 mg kg-1) on approximately 50% of farms, while exchangeable K levels were moderate to high (76 to 160 mg kg-1) on all farms. Four farms adopting a "self-sufficient" approach, producing most feed on-farm, imported little P as feed (1.37 to 1.90 kg P ha-1 yr-1) and had negative average farm P balances (avg. -1.54 kg P ha-1 yr-1). An integrated nutrient management approach, along with a flexible feed import strategy, fosters the sustainability of organic dairying systems. Key words: Organic dairying, nutrient budget, nitrogen, potassium, phosphorus, soil fertility

Description: Cutans that coat and link sand grains in cemented podzolic B horizons (ortstein) of well and poorly drained podzolic soils from Nova Scotia and New Brunswick were described in thin sections and analyzed by energy dispersive spectrometry (EDS). The principal type of cutan was brown and weakly to moderately anisotropic; it included numerous silt and fine sand grains. X-ray spectra showed this type to be composed dominantly of Al and Si with lesser amounts of K and Fe, and minor amounts of P, S, and other elements. The silt and clay particles of these cutans were apparently impregnated with Al, Fe-organic complexes. Another common type of cutan was dark reddish brown, monomorphic and isotropic; it consisted mainly of Al and organic matter as indicated by dominant Al and weak P and S peaks. In a few samples such cutans were composed mainly of Fe and organic matter. Rarer black cutans contained Mn in various proportions. The dominant cementing material of these ortstein horizons was shown to be organic complexes of Al and, less commonly, of Fe. The genesis of soils with ortstein is discussed.

Description: International initiatives such as the United Nations Framework Convention on Climate Change and the Kyoto Protocol require that countries calculate national inventories of their greenhouse gas emissions. The objective of the present study was to develop a country-specific (Tier II) methodology to calculate the inventory of N2O emissions from agricultural soils in Canada. Regional fertilizer-induced emission factors (EFreg) were first determined using available field experimental data. Values for EFreg were 0.0016 kg N2O-N kg-1 N in the semi-arid Brown and 0.008 kg N2O-N kg N-1 in the sub-humid Black soil zones of the Prairie region, and 0.017 kg N2O-N kg-1 N in the humid provinces of Quebec and Ontario. A function relating EFreg to the "precipitation to potential evapotranspiration" ratio was determined to estimate annual emission factors (EFeco) at the ecodistrict scale (≈ 150 000 ha) in all agricultural regions of Canada. Country-specific coefficients were also developed to account for the effect of several additional factors on soil N2O emissions. Emissions from fine-textured soils were estimated as being 50% greater than from coarse- and medium-textured soils in eastern Canada; emissions during winter and spring thaw corresponded to 40% of emissions during the snow-free season in eastern Canada; increased emissions from lower (wetter) sections of the landscape and irrigated areas were accounted for; emissions from no-till soils were 10% greater in eastern, but 20% lower in western Canada than from those under conventional tillage practices; emissions under summerfallow were estimated as being equal to those from soils under annual cropping. This country-specific methodology therefore accounts for regional climatic and land use impacts on N2O emission factors, and includes several sources/offsets that are not included in the Intergovernmental Panel on Climate Change (IPCC) default approach. Key words: Nitrous oxide, soils, greenhouse gases, inventory

Description: A field experiment was conducted for 8 yr (from 1994 to 2001) in a Black Chernozem (Udic Haploboroll) high in organic C (5.5%) at Melfort, Saskatchewan, Canada, to assess the environmental impact of tillage and crop rotation. Short-term effects on residue cover, soil temperature, moisture, aggregation, bulk density and hydraulic conductivity were measured, and long-term effects on total organic C (TOC) and N (TON), and light fraction organic C (LFOC) and N (LFON) were determined. There were two tillage systems [no tillage (NT) and conventional tillage (CT)] and three 4-yr annual crop rotations (canola-wheat-barley-barley,canola-barley-pea-wheat,and canola-pea-flax-barley). Straw was returned to soil every year in all treatments with the exception of flax residue. Soil samples were taken for analysis of organic C and N after the harvest of canola at the end of second 4-yr rotation cycle. Residue cover on soil was higher under NT than CT. Soil temperature was lower and soil moisture was higher in spring, under NT than CT. The proportion of fine aggregates (〈 1.3 mm) in soil was lower and that of medium (2.0–12.7 mm) and large aggregates (〉 12.7 mm) was generally higher under NT compared with CT. The mean weight diameter (MWD) of aggregates was also larger under NT compared with CT in most cases. The proportion of fine aggregates was higher after canola compared with pea in some cases, but the proportion of medium and large aggregates was higher after pea compared with canola, and in rotations with 50% than 75% broadleaf crops in 2yr. Soil hydraulic conductivity and bulk density were lower under NT than CT in some instances. Compared with CT, NT had greater mass of TOC, TON, LFOC and LFON in soil. However, the differences were significant only for LFOC and LFON, in dicating that light fraction organic C and N was more responsive to NT than CT compared with total organic C and N. In conclusion, the findings suggest that there is no interaction between tillage and rotation, and that light fraction C and N accumulate when tillage is eliminated despite high levels of soil organic C in the soil. Key words: Aggregation, bulk density, crop rotation, hydraulic conductivity, organic C and N, moisture, residue cover soil, temperature, tillage

Description: It is well established that nitrous oxide (N2O) and carbon dioxide (CO2) emissions from agricultural land are influenced by the type of crop grown, the form and amount of nitrogen (N) applied, and the soil and climatic conditions under which the crop is grown. Crop rotation adds another dimension that is often overlooked, however, as the crop residue being decomposed and supplying soluble carbon to soil biota is usually from a different crop than the crop that is currently growing. Hence, the objective of this study was to compare the influence of both the crop grown and the residues from the preceding crop on N2O and CO2 emissions from soil. In particular, N2O and CO2 emissions from monoculture cropping of corn, soybean and winter wheat were compared with 2 -yr and 3-yr crop rotations (corn-soybean or corn-soybean-winter wheat). Each phase of the rotation was measured each year. Averaged over three growing seasons (from April to October), annual N2O emissions were about 3.1 to 5.1 times greater in monoculture corn (2.62 kg N ha-1) compared with either monoculture soybean (0.84 kg N ha-1) or monoculture winter wheat (0.51 kg N ha-1). This was due in part to the higher inorganic N levels in the soil resulting from the higher N application rate with corn (170 kg N ha-1) than winter wheat (83 kg N ha-1) or soybean (no N applied). Further, the previous crop also influenced the extent of N2O emissions in the current crop year. When corn followed corn, the average N2O emissions (2.62 kg N ha-1) were about twice as high as when corn followed soybean (1.34 kg N ha-1) and about 60% greater than when corn followed winter wheat (1.64 kg N ha-1). Monoculture winter wheat had about 45% greater CO2 emissions than monoculture corn or 51% greater emissions than monoculture soybean. In the corn phase, CO2 emissions were greater when the previous crop was winter wheat (5.03 t C ha-1) than when it was soybean (4.20 t C ha-1) or corn (3.91 t C ha-1). Hence, N2O and CO2 emissions from agricultural fields are influenced by both the current crop and the previous crop, and this should be accounted for in both estimates and forecasts of the emissions of these important greenhouse gases. Key words: Denitrification, soil respiration, rotation, crop residue

Description: Usage of mineral nitrogen (N) fertilizers for agricultural crop production systems is a major contributor to anthropogenic nitrous oxide (N2O) emissions. As part of a national study to quantify N2O emissions under different cropping systems and in different eco-regions, this study quantified the effect of fertilizer N rate on spring barley (Hordeum vulgare L.) on N2O emissions in 3 yr in a cool maritime climate with humid soil moisture regimes. Treatments were 0, 75 and 150 kg N ha-1 as ammonium nitrate applied as a pre-plant broadcast. N2O emissions were increased by fertilizer N application in each year. In 2003 and 2005, elevated N2O emissions occurred in the 6-wk period following fertilizer application when soil NO3-N concentrations were high. However, in 2004 and 2005, peak N2O emissions occurred near crop harvest. Elevated N2O emissions at this time were attributed to increased carbon availability due to re-wetting of dry soil. Therefore, the effect of fertilizer N management on N2O emissions may not necessarily occur immediately after treatment application. This emphasizes the importance of measuring N2O emissions outside of the crop growth period. Fertilizer-induced cumulative N2O emissions averaged 0.011 and 0.021 kg N kg-1 N when fertilizer N rate was increased from 0 to 75 kg N ha-1 and from 75 to 150 kg N ha-1, respectively, indicating increased N2O emissions when fertilizer is applied at above optimal rates. N2O emissions increased linearly with nitrate intensity, the summation of daily NO3-N concentrations for 0- to 15-cm depth. This suggests that the non-linearity in the relationship between fertilizer N rate and N2O emissions can be explained by the decreasing efficiency in crop NO3-N uptake at high fertilizer N rates. Key words: Hordeum vulgare, soil nitrate, denitrification, carbon availability

Description: International initiatives such as the United Nations Framework Convention on Climate Change and the Kyoto Protocol require that countries conduct national inventories of their greenhouse gas emissions. The primary objective of the present study was to apply a country-specific (Tier II) methodology at the regional (≈150 000 ha) scale to estimate direct N2O emissions from agricultural soils in Canada for the period 1990–2005. Other N2O sources such as manure management and indirect emissions were estimated using the Tier I Intergovernmental Panel on Climate Change (IPCC) methodology and were included to provide a complete assessment of agricultural N2O emissions. Total N2O emissions from agricultural sources averaged 58.1 Gg N2O-N yr-1 between 1990 and 2005 (from 48.9 in 1990 to 71.6 Gg N2O-N yr-1 in 2004). Of these mean emissions, 39.3 Gg N2O-N yr-1 or 68% were direct emissions from soils, 8.7 Gg N2O-N yr-1 or 15% were direct emissions from animal waste management systems and 10.1 Gg N2O-N yr-1 or 17% were from indirect emissions. Application of synthetic N fertilizers was the largest direct source of soil N2O with average emissions during the inventory period of 13.7 Gg N2O-N yr-1 or 35% of direct emissions. Crop residues (9.3 Gg N2O-N yr-1; 24%), grazing animals (6.8 Gg N2O-N yr-1; 17%) and manure applied to soils (4.1 Gg N2O-N yr-1; 10%) were the other major direct soil N2O sources. New non-IPCC N2O sources/offsets included in the Tier II methodology accounted for 10% of total direct soil emissions. Emissions occurring during summerfallow (2.2 Gg N2O-N yr-1; 6%), in lower portions of the landscape (2.2 Gg N2O-N yr-1; 6%), and following irrigation (0.7 Gg N2O-N yr-1; 2%) were partially offset by changes in tillage practices (-1.2 Gg N2O-N yr-1; -3%) and in coarse-textured soils (-0.2 Gg N2O-N yr-1; -1%). Differences in N2O estimates between Tier I and Tier II approaches mainly arise from the use of lower fertilizer-induced emission factors in the dry Prairie region and the addition of several new N2O sources/offsets in the Tier II methodology. Key words: Nitrous oxide, soils, greenhouse gases, inventory

Description: Twelve soil profiles, developed on gravelly parent material, have been sampled in the region of Quebec City and analyzed. Six profiles are developed on sandstones and shales whilst the six other profiles are formed on shales and mudstones. The shales, and to a lesser extent the sandstones, weathered readily to produce a large percentage of clay. Because of this, many B horizons with significant pyrophosphate-extractable Fe and Al do not meet the criteria for a Podzol B. The coarser than 2 mm material, which ranges in individual horizons from 14 to 82% in the first group of soils and from 0 to 84% in the second group, cannot be ignored as it contributes up to 69% of the total exchange capacity of the soil and therefore is important for the natural fertility of the soils. The differences between the stability of the gravel in air and in water also explain some of the problems in classifying these soils.

Description: Most pedotransfer functions (PTF) developed over the past three decades to generate water retention characteristics use soil texture, bulk density and organic carbon content as predictors. Despite the high number of PTFs published, most being class- or continuous-PTFs, the accuracy of prediction remains limited. In this study, we compared the performance of different class- and continuous-PTFs developed with a regional database. Results showed that the use of in situ volumetric water content at field capacity as a predictor led to much better estimation of water retention properties compared with using predictors derived from the texture, or the organic carbon content and bulk density. This was true regardless of the complexity of the PTFs developed. Results also showed that the best prediction quality was achieved by using the in situ volumetric water content at field capacity after stratification by texture. Comparison of in situ volumetric water content at field capacity, with the water retained at different matric potentials as measured in the laboratory, showed field capacity to approximate 100 hPa, whatever the soil texture. Finally, the lack accuracy of PTFs that do not use the in situ volumetric water content at field capacity as predictor did not appear due to the test soils being unrepresentative of the soils used to develop the PTFs, but were instead related to poor correlations between the predictors used and the water retention properties. Key words: Pedotransfer functions, root mean square error, mean error of prediction, standard deviation of prediction, texture, bulk density, organic carbon content

Description: Forty-three benchmark sites were established to monitor soils across the agricultural regions of Alberta. Soil chemical and physical properties were examined in an initial pedological investigation in 1997. This paper describes site selection and presents results from the initial pedological investigation. Ninety-five percent of the chosen sites were representative of their provincial ecodistrict, with only two profiles being darker and higher in organic carbon than expected. The majority of selected sites were gently undulating loam soils on morainal parent materials in the dryland regions of Alberta. Soil texture, cation exchange capacity, calcium carbonate content, and soil pH reflected regional differences in quaternary geology and agricultural practices across Alberta. Southern Alberta was characterized by high pH, sandier-textured soil profiles, whereas the Peace Lowlands, being derived from marine shale deposits, exhibited finer soil textures and higher cation exchanges capacities. Owing to climatic and vegetative differences, organic carbon levels were significantly greater in northern Alberta compared with the south, but were found to differ based on soil horizon and slope position. Upper slopes typically had lower organic carbon levels, particularly in the A horizon. Similar results were observed for total soil N, although other soil nutrients differed in relation to soil properties, slope and ecoregion. Data collected will provide: (a) the basis for a detailed Alberta soil quality assessment, (b) data for future modeling efforts, and (c) data necessary to identify temporal changes in soil properties, yield and management relationships. Key words: Agronomic practices, catena, ecodistrict, pedological investigation, soil landscape, soil quality

Description: In support of national environmental and economic modeling of agri-environmental indicators, greenhouse gases, carbon sequestration and policy assessment, fertilizer and manure nitrogen application rates were estimated for individual crops at the scale of the 1:1 m Soil Landscapes of Canada polygons. This database provides an estimate of the amount of nitrogen applied to each crop and is based on provincial fertilization recommendations, the type and number of livestock and manure produced and reported amounts of fertilizer sold. The database is being incorporated into ongoing programs related to international reporting, environmental performance and policy formulation at Agriculture and Agri-Food Canada.This paper describes the procedures developed to estimate fertilizer and manure nitrogen inputs for each crop type within each polygon. These procedures include: (i) the compilation of soil-specific recommended nitrogen application rates from provincial extension guide lines and experts; (ii) the calculation of total manure nitrogen production from animal numbers and excretion rates; (iii) the calculation of manure nitrogen available after land application losses and (iv) the adjustment of total fertilizer nitrogen applied to match reported sales at the provincial level. The calculation procedures were incorporated into the Canadian Agricultural Nitrogen Budget model, with provisions for transferring the data to other models and for other applications. Key words: Fertilizer nitrogen, manure nitrogen, nitrogen application rates, nitrogen model, Soil Landscapes of Canada, Census of Agriculture

Description: The salinity tolerance of six annual crop species, wheat, oats, barley, rye, flax and rapeseed, were determined on saline soils that occur north of the Quill Lakes in the northeastern corner of the agricultural area of Saskatchewan. The relative merits of a salt-tolerant grass-legume mixture were also given consideration. The effects of salt stress on spring-sown cultivars became most apparent following exposure to hot, dry summer weather. In contrast, maximum salt tolerance for both winter wheat and winter rye was a function of winterkill. The winterhardiness of both winter annuals was reduced by saline conditions, but winter rye was more adversely affected than winter wheat. Large decreases in seed yield, plant dry weight and height occurred before the effects of increased soil conductivity were expressed for hectoliter weight, 1000-kernel weight, date of maturity, protein content and oil content. Among the spring and winter annual cultivars considered, Bonanza barley and Garry oats demonstrated the greatest salt tolerance. However, where severely saline conditions occurred, mixtures of salt-tolerant perennial grasses and alfalfa proved to be more productive than either barley or oats. The salinity tolerance of all cultivars was greater for years with more favorable growing conditions. It was apparent that stress factors, such as soil salinity, cold, heat, drought, etc., have a cumulative effect in reducing crop performance. This observation emphasizes the importance of minimizing all stress factors when attempting to crop saline soils. Detailed soil analyses indicated that where salts were a problem, the level of salinity was extremely variable, often changing dramatically over short distances. This extreme variability made it difficult to assess the magnitude of the salinity problem. In this regard, crop performance, especially plant height, provided a good indicator for identifying saline areas for purposes of soil testing.

Description: Compost contributes plant-available nutrients for crop production and adds partially decomposed carbon (C) to the soil organic carbon (SOC) pool. The effect of compost applications and other agricultural practices on SOC and total nitrogen (N) pools was determined in a sandy-loam Humic Gleysol at the Research Farm of McGill University, Ste-Anne-de-Bellevue, Quebec. Experimental plots with continuous silage corn (Zea mays L.) and silage corn-soybean (Glycine max L. Merr.) production were under conventional tillage (CT) or no-tillage (NT) management. Composted cattle manure was applied each spring at rates of 0, 5, 10 and 15 Mg (dry weight) ha-1 and supplemental NPK fertilizers were added to meet crop requirements. The C input from crop residues was affected by tillage, crop rotations and compost application, but differences in the SOC and total N pools were due to compost applications. After 5 yr, compost-amended plots gained 1.35 to 2.02 Mg C ha-1 yr-1 in the SOC pool and 0.18 to 0.24 Mg N ha-1 yr-1 in the total N pool, as compared with initial pool sizes when the experiment was initiated. These gains in SOC and total N were achieved with agronomic rates of compost and supplemental NPK fertilizers, selected to match the phosphorus requirements of silage corn. Such judicious use of compost has the potential to increase the SOC and total N pools in agroecosystems under annual crop production. Key words: Composted cattle manure, corn silage, mineral fertilizer, plant-available nitrogen, soil organic carbon

Description: Fluorescence excitation spectra of fulvic acid (FA) and humic acid (HA) were recorded at different pH as well as at different netural salt concentrations. Spectra of both FA and HA exhibited distinct bands at 465 nm, while spectra of FA showed additional bands at 360 nm. Fluorescence intensities decreased with decreasing pH and increasing ionic strength. This is due to decreasing ionization, increasing particle association, and to coiling of macromolecular structures. The fluorescence characteristics of FA and HA were observed to be related to the free radical content, color, and phenolic structures. Our data show that fluorescence excitation spectra can be utilized for differentiating between soil FA and HA.

Description: Distinction of autotrophic (root, Rr) versus heterotrophic (Rh) soil respiration is important to understanding C balance in forest ecosystems and the contribution of both respiration components to total soil respiration (Rs) may change as stands mature. We studied Rr and Rh in a chronosequence of hybrid poplar plantations that were 4, 6, 8, and 13 yr old in summer 2005. We hypothesized that Rr will become increasingly larger and will also represent a greater proportion of Rs as plantation age increases. Our results showed that both Rs and Rh showed significant seasonal variations; however,Rr were much more variable. No significant differences among plantation ages were observed for any of the respiration parameters (Rr, Rh and Rs) measured throughout the summer. No significant differences were found for the contribution of Rh to Rs between plantation ages or between sampling dates. The average proportion of Rh to Rs across all sites and sampling dates was 0.63 ± 0.026 (mean ± standard error), indicating that heterotrophic respiration dominated total soil respiration in the studied hybrid poplar plantations.The power of the statistical tests in this study was likely quite low due to the inclusion of only two replicates for each plantation age. Key words: Autotrophic, heterotrophic respiration, root exclusion, trenching, hybrid poplar, chronosequence

Description: Nitrous oxide emissions are highly episodic and to accurately quantify them annually, continuous measurements are required. A tower-based micrometeorological measuring system was used on a commercial cattle farm near Cô teau-du-Lac, (QC, Canada) during 2003 and 2004 to quantify N2O emissions associated with the production of edible peas. It was equipped with an ultrasonic anemometer and a fast-response closed-path tunable diode laser. Continuous measurements of N2O fluxes were made during the spring thaw following corn cultivation in summer 2002, then during an edible pea growing season, followed by cattle manure application, cover crop planting and through until after the next spring ploughing. The cumulative N2O emissions of 0.7 kg N2O-N ha-1 during the initial snowmelt period following corn harvest were lower than expected. Sustained and small N2O emissions totalling 1.7 kg N2O-N ha-1 were observed during the growing season of the pea crop. Solid cattle manure applied after the pea harvest generated the largest N2O emissions (1.9 kg N2O-N ha-1 over 10 d) observed during the entire sampling period. N2O emissions associated with the cover crop in the fall were mostly influenced by manure application and totalled 0.8 kg N2O-N ha-1. For the subsequent spring thaw period, N2O emissions were 0.8 kg N2O-N ha-1. This represents approximately 15% of the annual emissions for the edible pea-cover crop system, which totalled 5.6 kg N2O-N ha-1 over the measuring periods. There was little difference in spring thaw N2O emissions between the two growing seasons of corn and edible pea-cover crop. Key words: Nitrous oxide emissions, legumes, snowmelt, dairy manure, tunable diode laser, flux tower

Description: The distribution, composition and nature of concretions occurring in some moderately well-drained to poorly drained soils of Saskatchewan were investigated. The soils selected were: Gleyed Humo-Ferric Podzol, Orthic Luvic Gleysol, Orthic Gray Luvisol and Gleyed Gray Luvisol. The concretions range from  15 mm in diameter and are distributed throughout the sola with maximum concentrations of about 8% in Aeg and Bf horizons. The data indicate that the concretions from Gleysolic and Gray Luvisolic soils are markedly higher in Fe, Mn and P than the surrounding soil matrix; concretions from the Podzol are high in Fe but very low in Mn and P. Mn is directly related to the size of concretions whereas Fe and P contents generally increase with decreasing size of concretions. The formation of concretions and their significance in soil genesis are discussed.

Description: Many measurements of oxygen flux in mineral soils have been reported; however, few such measurements have been made in organic soil. Almost all reported measurements of oxygen flux are at constant applied voltage, despite criticism of this technique, possibly due to the complexity of existing techniques for measuring oxygen flux at effective voltage. Equipment suitable for measuring oxygen flux at applied and effective voltage in organic soil was designed, and simplified techniques were developed and tested. As reported for mineral soils, soil resistance is relatively constant spatially and with depth in individual soils. Limited poisoning of the platinum electrode surface occurred after long periods of time and, contrary to previous assumptions, cannot be detected by erratic readings. Unlike mineral soil, the amperage-voltage slopes are constant over a wide range of organic soils, simplifying the technique for estimating oxygen flux at constant effective volatage. Comparison of simultaneous measurements of oxygen flux at constant and effective voltage indicates that oxygen flux measurements at effective voltage were twice those at applied voltage and strongly correlated (r2 = 0.96, n = 22).

Description: One of the key factors in phosphorus management is the P retention capacity (PRC) of the soil. In our previous study, we formulated several equations for estimating the phosphorus retention capacity of Manitoba soils. The objectives of the current study were to evaluate these equations using independent soil samples and to evaluate the influence of manure application on the predictive ability of these equations. Forty representative surface soil samples (20 soils with history of manure application and 20 without manure application history) were collected from across Manitoba. The P retention index (P150) and Langmuir adsorption maximum (Smax) were determined in the laboratory. The measured P retention capacities were then compared with those estimated using the formulated equations. Surprisingly, P150, which was obtained from a single measurement, was more robust than Smax that was obtained from at least 17 measurements as the equations provided a better estimate of P150 than Smax. Equations that were based on soil particle sizes (either percent clay or percent sand) provided poor estimates of soil PRC for the whole soil collection. However, when the soils were grouped on a pH basis, soil particle size worked better for soils with pH

Description: The ways in which agricultural soils are managed influence the production and emission of nitrous oxide (N2O). A field study was undertaken in 2003, 2004, and 2005 to quantify and evaluate N2O emission from tilled and no-till soils under corn (Zea maysL.) and soybeans (Glycine max L. Merr) in Ontario. Overall, N2O emission was lowest in 2003, the driest and coolest of the 3 yr. In 2004, the significantly larger annual N2O emission from no-till soils and soils under corn was attributed to an episode of very high N2O emission following the application of fertilizer during a period of wet weather. That the N loss by N2O emission occurred only in no-till soils and was large and long-lasting (~4 wk) confirms the strong effect that management has in reducing fertilizer N losses. In 2005, tilled soils had significantly larger N2O emission than no-till soils, most of which was emitted before the end of June. Because the tilled soils were better aerated , nitrification was likely the primary process contributing to the larger emission. Relatively low N2O emission from soybeans suggests biological N fixation does not appear to contribute substantially to the annual N2O emission. Further study of methods to reduce N2O emission in agricultural systems should focus on improving N use efficiency within a particular tillage system rather than looking to differences between tillage systems. Key words: Tillage, corn, soybeans, nitrogen, nitrous oxide, biogenic gas emission, nitrification, denitrification, fertilization

Description: An improved procedure for measuring water retention curves at low suction (0–300 mbar) by the hanging-water-column method is described. The proposed method produces curves obtained on the same sample over the whole range of measurements. Good agreement was found between data measured by the proposed technique and those obtained by a conventional pressure plate technique.

Description: An increase in wheat yield in 1977 on an Elstow silt loam to levels slightly greater than those of the checks was obtained on dolomite-treated (11.2 and 22.4 t/ha) plots that had formerly received 17.9 and 33.6 t/ha KCl dust, and had subsequent wheat yield reductions of 21 and 53% in 1973, and rapeseed yield reductions of 19 and 25% in 1975. Water-soluble and NH4 Ac-extractable K in the surface horizons were increased by high application of KCl, and the Ca and Mg were reduced; K was not increased below the 55-cm depth. An application of 33.6 t/ha KCl had made this soil, below 45 cm, slightly saline due to Ca and Mg from the upper horizon’s exchange complex, and Cl from the added KCl. Eighteen months after the application of dolomite, K was slightly reduced, Ca mainly restored, and Mg partly restored in the surface 15 cm of this soil. Forty percent of the Cl applied with 33.6 t/ha KCl had leached beyond 213 cm by 1976. An upward movement of Ca and MgCl occurred during 1977.

Description: An understanding of the impact of repeated manure additions on soil phosphorus (P) is needed to determine appropriate manure application rates for prairie soils and manure sources. The objective of this study was to assess the loading of manure-derived phosphorus using P budgets and soil P measurement techniques applied to two Saskatchewan soils with known histories of manure application. Liquid hog manure (LHM) and solid cattle manure (SCM) treatments were applied annually over 8 yr to Black Chernozemic soils (Dixon site), and LHM was applied to Dark Brown Chernozemic soils (Plenty site) over 6 yr. Soil samples were collected in the spring of 2003 and 2004 and analyzed for labile P (Modified Kelowna extractable, Olsen extractable, water extractable, and Plant Root Simulator exchange resin methods) and total P. The P budgets were in good agreement with the observed patterns in labile soil P at the two sites. The annual application of LHM (37000 L ha-1 yr-1) at agronomic nitrogen (N) rates with no additional P fertilizer (Dixon only) did not significantly elevate soil labile P compared with the unfertilized controls at both Dixon and Plenty. The annual application of SCM (7.6 Mg ha-1 yr-1) at agronomic N rates did not significantly elevate soil labile P compared with the unfertilized control at Dixon; whereas of SCM at higher rates (15.2 Mg ha-1 yr-1 and 30.4 Mg ha-1 yr-1) showed some elevation in labile soil P. Measures of labile P were sensitive to P surpluses or deficits predicted by P balances, and all methods of measuring labile soil P were strongly correlated with one another at both sites (r ≥ 0.803 at P ≤ 0.01). Key words: Manure, cattle manure, nitrogen, phosphorus, soil test phosphorus

Description: Humus fraction distribution in a wide range of horizon samples was examined by measuring carbon content in humic acid (Ch), in fulvic acid (Cf) and in the strongly colored polyphenolic component of the fulvic acid fraction (Ca). Fraction distribution was described by the ratios Ch/Cf and Ca/Cf. It was concluded that humus fraction ratios were related to horizon types as used in the Canadian System of Soil Classification, and were effective in discriminating between certain horizon types, particularly between Luvisolic Bt and Podzolic Bf. The results also suggested that humus fraction ratios may be effective in separating distinct sub-populations within Ah horizons and Bf horizons in general, based on qualitative differences in organic matter present. Aspects of the role of humus fractions in soil genesis are discussed.

Description: Canada annually reports on all of its annual greenhouse gas emissions to the United Nations Framework Convention on Climate Change (UNFCCC), including estimates of CO2 emissions and removals from cropland management. Soil carbon (C) change in cropland resulting from management is estimated by using C change factors multiplied by the area of cropland subjected to a management change. In this paper we compare soil C change factors in Canadian cropland obtained using a C modelling approach (Century model) to both empirical estimates obtained from the scientific literature, and to default Intergovernmental Panel on Climate Change (IPCC) estimates. Factors were estimated for land management changes from annual to perennial cropping, tillage to no-tillage and from summer fallow to continuous cropping. Empirical data comparing C change between conventional tillage (CT) and no-tillage (NT) were highly variable, but the modelled factors were still within the range derived from the empirical data. Factors for changes from CT to NT varied from 0.06 to 0.16 Mg C ha-1 yr-1 across the country. When considering the change from annual to perennial cropping, the modelled factors ranged from 0.46 to 0.56 Mg C ha-1 yr-1, which is in the range of empirical values, and were slightly greater in the eastern than the western soil regions. For conversion of crop-fallow to continuous cropping, the modelled rate of C storage (0.33 Mg C ha-1 yr-1) was more than double the average rate of 0.15 ± 0.06 Mg C ha-1 yr-1 derived from two independent assessments of the literature. For each of the management changes considered, the modelled factors were generally lower than IPCC estimates, and this is partly attributable to differences in calculation methods and to the fact that C changes likely occur more slowly in the cold climate of Canada. Generally, the results show that the modelling approach used at present to derive C change factors for use in Canada's inventory is adequate. However, soil C change factors for cropland soils in Canada would be greatly improved by a reduction in the high variability usually associated with empirical data, and by improved simulation of the Century model under varying management conditions. Key words: Soil organic carbon, Canada, tillage, perennial cropping, cropping intensity, carbon change factors

Description: An efficient nitrogen fertilizer recommendation for plant production depends on the amount of N supplied by the soils. A study to investigate the characteristics of net N mineralization in typical paddy soils in an important rice production area of China was conducted on aerobic soils for 147 d of incubation at 25°C. Results showed that the organic nitrogen mineralized ranged from 40 to 360 mg N kg-1 or from 2.92 to 14.17% of total N. In a partial correlation analysis, the N mineralized was only correlated with total N and alkaline hydrolyzable N. Principal component analysis indicated two types of soil physical and chemical properties, each with different influence on N mineralization. Four models: (1) an effective cumulated temperature model (Temperature model), (2) a one-component, first-order exponential model (One-pool model), (3) a two-component, first-order exponential model (Two-pool model), and (4) a two-component, mixed first- and zero-order exponential model (Special model) were fitted to the measured amounts of N mineralized over time using a non-linear regression procedure. All models gave good fits. Model parameters were compared and correlated with the soil basic properties and nitrogen availability indices. All results showed that the Special model performed a better prediction of net nitrogen mineralization in paddy soils under non-flooded conditions than the other models investigated. Key words: Seasonally flooded soil, aerobic net N mineralization, simulation modeling, nitrogen availability indices

Description: Manure is known to increase soil N2O emissions by stimulating nitrification and denitrification processes. Our objective was to compare soil-surface N2O emissions following the application of liquid and solid dairy cattle manures to a loamy and a clay soil cropped to silage maize. Manures were applied in 2 consecutive years at rates equivalent to 150 kg total N ha-1 and compared with a control treatment receiving an equivalent rate of synthetic N. Soil-surface N2O fluxes, soil temperature, and soil water, nitrate and ammonium contents were monitored weekly in manured and control plots. From 60 to 90% of seasonal N2O emissions occurred during the first 40 d following manure and synthetic fertilizer applications, indicating that outside that period one or several factors limited N2O emissions. The period of higher emissions following manure and fertilizer application corresponded with the period when soil mineral N contents were highest (up to 17 g NO3−-N m-2) and water-filled pore space (WFPS) was greater than 0.5 m3 m-3. The absence of significant N2O fluxes later in the growing season despite high WFPS levels indicated that the stimulating effect of organic and synthetic N additions on soil N2O production was relatively short-lived. Fertilization of silage maize with dairy cattle manure resulted in greater or equal N2O emissions than with synthetic N. This was observed despite lower overall soil mineral N contents in the manured plots, indicating that other factors affected by manure, possibly additional C substrates and enhanced soil respiration, resulted in greater denitrification and N2O production. Silage maize yields in the manured soils were lower than those receiving synthetic N, indicating that the N2O emissions per kilogram of harvested biomass were greater for manures than for synthetic N. Our results also suggest that the main source of N2O was nitrification in the loam and denitrification in the clay soil. There was no clear difference in N2O emissions between liquid and solid manures. The variable effects of liquid and solid manure addition reported in the literature on soil N2O emissions likely result from the variable composition of the manures themselves as well as from interactions with other factors such as soil environment and farming practices. A better characterization of the availability of manure C and N is required to assess the impact of manure application on soil N2O emissions under field conditions. Key words: Greenhouse gases, N2O, maize, manure

Description: Growth chamber studies were conducted on the relative effects of various placements of NH4H232PO4 applied at 20 kg P ha−1 in a single band away from the seed on growth, and on uptake of soil and fertilizer P by flax (Linum usitatissimum L. ’Linott’) grown on two P-deficient Chernozemic soils; one calcareous, the other non-calcareous. Crop response was very sensitive to location of the placed P. Placement of the P away from, and up to 3.0 cm to the side and from 0–4.5 cm below the seed on average increased aboveground dry matter yield and P uptake of flax 8 wk after seeding by 2.3- and 2.1-fold, respectively, compared with the non-P fertilized soils. Maximum yields and P uptake, which were approximately four and three and a half times greater, respectively, than the non-P fertilized values, were achieved by placing the P no more than 1.5 cm to the side and 1.5–3.0 cm below the seed. Flax root development studies indicated that this was due largely to root development during the first few weeks being limited to a small cylinder of soil immediately surrounding the single vertical tap root. Distance of placement of P away from the seed was more critical for the calcareous soil, with crop use of the applied P being noticeably less for this soil (4.8–17.3%) than for the non-calcareous soil (18.3–40.2%).

Description: Three non-replicated, non-fertilized, dryland grain rotations — continuous wheat, wheat-fallow, and wheat-wheat-fallow — were established in 1912 on a Dark Brown Chernozemic soil. In 1967, the rotations were altered to include an annual application of 45 kg N/ha to a portion of each field. Above- and below-ground organic residue and soil were sampled in September 1975, April and August 1976, and April 1977 from both the fertilized and non-fertilized treatments of each rotation to measure the effects of the rotations on a number of chemical characteristics. The soil samples were analyzed for pH and contents of C, N, ethanol/benzene- and resin-extractable C, polysaccharides, and waterstable aggregates. The organic residues were analyzed for contents of C, N, ethanol/benzene-extractable C, lignin, and methoxyl groups, and for caloric content. The soils of the continuous wheat rotation contained the most C, total N, and polysaccharides, whereas the soils of the wheat-fallow rotation were about 12 percentage points higher in resin-extractable C than those of the continuous wheat or wheat-wheat-fallow rotations. The cultivated soils contained 47% less C, 46% less N, 53% less polysaccharides, 100% more solvent-extractable C, 49% more resin extractable C, and a slightly higher pH than the soils from the proximate native grassland. Individual rotations had little effect on the chemical composition of organic residues on the soil surface but did affect the decomposition and nature of subsurface plant residues.

Description: Three years after disturbance of soil, by digging sample pits to a depth of 1 m, soil at a depth of 85–95 cm had greater air porosity and greater total porosity than previously and soil strength of disturbed soil was much less than strength of the undisturbed side wall. At a depth of 25–35 cm, air porosity was increased and soil strength was decreased. Disturbance of wet soil tended to have less beneficial or detrimental effects. These data suggest than Berwick and Kentville sandy loams would be amenable to improvement by deep tillage provided moisture conditions were favorable.

Description: Atomic absorption analyses of pyrophosphate extractions of B horizons from some Luvisolic, Gleysolic and Solods had higher Fe and Al contents when using 0.1% Superfloc and low speed centrifugation than those obtained when using 0.2% or 0.5% Superfloc or when using high speed centrifugation. Laboratories not equipped with a high speed centrifuge should use a method other than Superfloc to clarify the solution or use the recommended colorimetric method.

Description: The inorganic clay constituents of the B horizons of three Podzolic soils from British Columbia were analyzed by X-ray diffraction, infrared, electron-optical and chemical methods. The amorphous inorganic constituents comprised from 51 to 82% of the clay in these Podzol B horizons. Quartz, feldspar, chlorite, and vermiculite were the dominant minerals in the crystalline portion of the clay. Infrared spectra suggested the presence of appreciable amounts of imogolite in the fine clays of the three soils. Electron optical evidence confirmed its presence in small amounts (

Description: The internal drainage of a saline-sodic soil having till at 51 cm from the surface was studied in the field and laboratory. Average water intake (infiltration) for the profile was 3.76 cm/day. The Btj could be a limiting factor for vertical flow. The horizontal hydraulic conductivity indicated that lateral flow of water in the C horizon (36 cm/day) and surface of the till (22 cm/day) could be as much as five times greater than that of the Ah (5 cm/day) and Btj (8 cm/day) horizons. Salts were leached from the profile by the 22 cm of water that had been applied. It was concluded that the internal drainage of the soil was sufficient to accommodate infiltrated water under normal conditions, and that the buildup of a water table and salinization of the soil were probably due to lateral flow of water from canal seepage and irrigation mismanagement.

Description: These calcareous brown soils are low in organic matter. The clay and carbonate content increase with depth. Carbonate percentage ranges from 1.7 to 27.5% and the accumulation is found between 45 and 105 cm from the soil surface. Sulfate exceeds chloride ions in the soil extract. The exchange capacity, varying from 8.2 to 27.9 meq/100 g of soil, increases with depth. The major clay mineral is vermiculite and the maximum percentage is found in the lower horizons, while illite, which is the second clay mineral in these soils, decreases with depth. There was a relationship between K+ fixation and the content in clay and vermiculite. K+ fixation, which represents 7–11% of the cation exchange, is also enhanced by the drying of the soil.

Description: Four series of agricultural soils of Quebec were sampled in the Lowlands on drained and undrained sites in order to investigate the effect of long-term internal drainage on the physical and chemical properties of the profiles. Change in structure was observed in the Ste-Rosalie soils. A massive layer found below 18 cm in the undrained profile was replaced by a more structured layer at greater depth in the drained profiles. Occurrence of mottles down to the Cg horizon reflected the better aeration conditions in the drained sites. Saturated hydraulic conductivity values were sometimes higher and sometimes lower than those measured in the undrained profiles. Below the plow layer, the two profiles drained for more than 50 yr had a cation exchange capacity 12–15% higher than the undrained profiles. Oxalate-extractable iron represented a high percentage of the dithionite-extractable iron and indicated a low rate of formation of crystalline pedogenic oxides. Mn accumulations were found in the more compact layers. The improvement of internal drainage requires a soil management that will enhance soil structure.

Description: Forty-nine sandy soils developed in till, outwash, alluvium and marine sands were studied to determine the effect of mode of deposition on soil development and to classify the soils according to the Canadian and U.S. classification systems. Forty-three of the soils met the morphological and chemical criteria of Humo-Ferric Podzols but none of these was a Spodosol because the ratio of pyrophosphate-extractable Fe + Al to clay in the B horizon was below 0.2. Mode of deposition had only a minor effect on soil evolution. However, B horizon development was strongest in the till soils, perhaps because of their somewhat finer texture and greater age. A pronounced maximum of clay occurred in the B horizons of the Podzolic soils; commonly, clay in the B exceeded that in the A and C by a factor of 2–5. A higher pyrophosphate Al/Fe ratio was found associated with soils low in total pyrophosphate Al + Fe and vice versa. It was also found that pyrophosphate Al + Fe was positively correlated with total organic C (r = 0.891).

Description: Analysis by energy dispersive X-ray spectrometry (EDS) of cutans linking grains in coarse-textured duric horizons with plectic fabrics indicated that Al-organic material was a component of the cement. (Al, Fe)-organic material occurred in voids near the upper surface of duric horizons with porphyroskelic fabrics but EDS was not useful in detecting the cement of such horizons. Ground (2 mm) sandy loam C horizon material from a soil with a dense duric horizon was cemented strongly by as little as 0.1% (Al + Fe) precipitated with Na2 SiO3. Results of this and previous studies suggest that various combinations oa Al, Fe and Si hydrous oxides and humified organic matter act as cementing agents of duric horizons and that very little cement is required to indurate closely packed materials.

Description: The effect of degree of decomposition and depth of sampling on gamma probe wet bulk density measurements was investigated for two organic soils. Sampling depth did not significantly affect the probe calibration. In situ calibration must be done rather than in laboratory.

Description: The neutral monosaccharides released by the acid hydrolysis of five peat profiles were analyzed by ion exchange chromatography and gas-liquid chromatography in order to ascertain whether monosaccharide composition can be used to differentiate peats. Glucose, mannose and galactose were the predominant monosaccharides found. Changes observed with depth in the relative abundances of the monosaccharides were not always correlated with the degree of decomposition as measured by fibre content or pyrophosphate index. The arabinose to xylose ratio was a diagnostic chemical feature which reflected the degree of decomposition of the peats.