ALBERT

Description: Our previous work has demonstrated a relationship between polarity index and organic carbon referenced partition coefficients (Koc) of organic chemicals. Here we compare sorption of benzene, toluene, or o-xylene by protein with non-protein organic sorbents. Koc for benzene, toluene, or o-xylene sorption by collagen was much higher than by lignins, humic acid, chitin, or cellulose. Sorption of benzene, toluene, or o-xylene was not only influenced by organic sorbent polarity and functionality (e.g., aromaticity), but also by additional properties which we inferred related to physical conformation of the organic sorbents. In this respect, collagen exhibits unique sorptive behavior toward removal of nonpolar organic chemicals in the aqueous phase, which was not shared by humic acids of similar C, O or N content. Key words: Sorption, collagen, lignin, polarity, hydrophobic domains

Description: Using previous years’ yield patterns may be one method of breaking a field into management zones for the purpose of site-specific management. For this method to be useful there must be temporal stability of yield patterns and there must be a sound method of assessing the spatial-temporal stability of yield in a field. To this end, a method was developed to give a non-biased estimate of the within-field spatial-temporal stability of yield. The method determined the probability that the normalized yield for all years available at a given location in the field fit within the accuracy limits of the combine. Combine accuracies of ± 2.5%, 5% and 10% of the field mean yield and gridded data of 3 m, 6 m, and 9 m cell sizes, as well as crop choice were all included in the model to assess its sensitivity to changes in these factors. The resulting spatial-temporal stability maps were well correlated with visual estimations of the spatial yield patterns. The model results were highly influenced by the inputted combine accuracy, but grid size and crop choice had little affect on the proportion of the field or the spatial pattern of temporal stability in the two field sites examined. The sensitivity of the model to changes in the input value for the combine accuracy indicated that a good estimate of this value is required for the determination of the stable patterns in a field. Key words: Spatial-temporal stability, yield

Description: Increasing use of animal manures in Saskatchewan requires information on the effect of manure addition on the availability of soil K, Ca and Mg and their concentrations in plant tissue. To address these issues, we examined the effects of repeated application of liquid swine and solid cattle manure at low and high rates on extractable K, Ca and Mg in soils from three different long-term field trials in Saskatchewan, and on plant K, Ca and Mg concentrations in cereal straw grown on the soils. After 5 to 7 yr of manure application, extractable potassium in the soils was significantly increased, while extractable Ca and Mg tended to remain similar, or was decreased with swine manure addition. In the cereal straw, concentrations of K, Ca, and Mg were all increased by repeated swine manure application, such that there was no significant increase in the K/(Ca + Mg) ratio. However, the K/(Ca + Mg) ratio in the cereal straw grown on soil amended with the high rate of cattle manure was increased. These findings suggest that increased risk of tetany potential from manure application would mainly be associated with excessive application rates of cattle manure in these soils, but should be monitored in feeds grown on all manured soils.Key words:Soil extractable K, Ca, Mg and Na; cereal K, Ca and Mg concentrations, K/(Ca + Mg) ratio, tetany potential, urea, swine manure, cattle manure

Description: There is a need to develop verifiable algorithms that can be easily applied to estimate carbon sequestration in soils. A simple process-based empirical model, driven primarily by soil texture and crop residue input, was developed to account for changes in soil organic carbon (SOC) in Chernozemic soils on the Canadian prairies. The model was used to estimate SOC change under no-till and continuous cropping compared with conventional tillage and rotations with fallow. Using this model, C sequestration due to continuous cropping compared with fallow-containing rotations was determined to be 0.09 Mg C ha-1yr-1 for the Brown and Dark Brown, and 0.05 Mg C ha-1 yr-1 for the Black and Dark Gray/Gray soil zones. The rate of C sequestration as a result of continuous cropping was positively related to the frequency of fallow, which decreases on the prairies from the Brown, Dark Brown, and Black to the Dark Gray/Gray soil zones. Using this model average C sequestration when conventional tillage was converted to no-till, was 0.13, 0.23, 0.34, and 0.25 Mg C ha-1 yr-1 for the same soil zones, respectively. Combined gains due to no-till and continuous cropping in comparison with conventional tillage and fallow-containing rotations were determined to be 0.22, 0.32, 0.39, and 0.30 Mg C ha-1 yr-1 for the Brown, Dark Brown, Black and Dark Gray/Gray soil zones, respectively. Based on Agricultural Census of Canada data in 1996 and 2001, the amount of “C sequestered” due to the adoption of no-till was estimated to be 1.23 million Mg of C in 1996 and 1.72 million Mg of C in 2001, which is approximately 10% of the total greenhouse gas emissions from the agricultural sector in Canada. This simple process-based empirical model could serve as a useful tool for soil scientists to use in assessing soil sustainability and C sequestration in the Canadian prairies. It would also assist policy makers in understanding how various scenarios of improved management will influence future greenhouse gas emissions on agricultural soils. Key words: Soil organic carbon, no-till, fallow, crop rotation

Description: Selected surface horizons of grassland and forest soils formed under a cold, semi-arid climate were investigated to evaluate the formation of secondary minerals within the White River tephra, a Late Holocene rhyolitic tephra (~115014C yr BP) veneer that overlies the soil landscapes of central Yukon. Concentrations of extractable Fe (〈 0.48%), Al (〈 0.26%) and Si (〈 0.082%) concentrations in surface tephra-contaning horizons of grassland and forest pedons are low. The high amount of exchangeable calcium in grassland soils is likely due to cycling by vegetation and perhaps, aeolian inputs of Ca and Mg carbonates. Al is incorporated into Al-humus complexes in forest pedons and allophane in grassland pedons. Allophane content is low (〈 0.56%) in all soils as is ferrihydrite (〈 0.34%). Mineral composition of the sand fraction from tephra horizons is dominated by volcanic glass, plagioclase feldspars, amphiboles, epidote, pyroxenes and very limited quantities of quartz and primary Fe oxides. Chlorite and an expanding phyllosilicate were also detected and are assumed to be of detrital origin. Clay mineralogy is dominated by volcanic glass, quartz, feldspars and minimal quantities of kaolinite and dehydrated halloysite in surficial horizons. Kaolinite is assumed to be of detrital origin while dehydrated halloysite is a product of a low leaching and dry environment where limited resilication occurs. Scanning electronmicroscopy (SEM) investigation indicates the presence of opaline silica in surface horizons from forest pedons which has likely formed due to freezing of the soil solution in combination with dehydration and resilication. Overall, the soil horizons formed within the veneer of White River tephra have experienced minimal weathering and very little silicate clay mineral development. Key words: Tephra, glass, Yukon, minerals (secondary), weathering

Description: The potential for sustainable agricultural practices to sequester C is substantial. The economic feasibility and competitiveness of soil C sequestration depends on the opportunity cost per tonne of C stored. The key issue is whether the cost is competitive with alternative methods of reducing greenhouse gas emissions. The high spatial variability in land productivity means that the soil characteristics are important when designing public policies to address this issue. Empirical evidence suggests that the opportunity cost per tonne of C stored can be as low as US$10 to US$25 t-1 (Can$12–30), but that for the majority of temperate agriculture it exceeds US$50 t-1 (Can$60). The final monetary value placed on a tonne reduction of C will emerge either from the establishment of a fully functioning market or from government payment schemes. Estimates of the value of stored C have ranged from US$100 t-1 (Can$120) to a low of less than US$5 t-1 (Can$6). Current evidence suggests a likely price in the lower region of this range. Key words: Carbon farming, carbon sequestration, soil organic carbon, soil sustainability

Description: Soil water limits plant growth in the Canadian Prairie Provinces. Efficient use of soil water is, therefore, paramount in crop production. Two 2-yr field studies were conducted (i) to determine the effects of crop selection and cropping practice on the temporal and spatial distribution of soil water and (ii) to quantify water use and water-use efficiencies (WUE) of alternative crop/cropping systems for a subhumid region of Alberta. The first study was at the Ellerslie Research Station on an Orthic Black Chernozemic and the second at the University of Alberta Breton Plots on an Orthic Gray Luvisol. At each site three annual crops/cropping systems [barley (Hordeum vulgare L.), barley intercropped with field pea (Pisum sativum L.), and faba bean (Vicia faba L.)] and a perennial forage [creeping red fescue (Festuca rubra)] were grown in 1987 and in 1988. At Ellerslie, tillage methods to grow annual crops were conventional and zero tillage. At Breton, the two tillage methods used were: (i) conventional and (ii) deep tillage (to enrich the surface horizon with clay from the subsoil). The experimental design used was a split plot with four replications. Soil water was measured by neutron attenuation. Evapotranspiration was calculated as the change in soil water to 0.80-m depth plus precipitation. Soil water changes were more closely associated with the kind of crop grown than with the method of tillage used. The barley/field pea intercrop exhibited a pattern of water use similar to barley. Greater water-use efficiency measured in the intercrop system was attributed to differences in canopy structure and plant biomass production. Faba bean and red fescue had lower WUE than barley and the intercrop. The water requirement by faba bean was close to that of red fescue and related to leaf area development. Small tillage effects on soil water were observed during 1988. Soil water under zero tillage was greater than under conventional tillage. Faba bean and red fescue are likely to succeed more in agro-ecological regions such as Breton. Further studies are required to improve our understanding of the effects of these cropping systems on water resources when they are used in rotational-production systems. Key words: Barley, field pea, faba bean, creeping red fescue, conventiional tillage, zero tillage, deep tillage, water-use efficiency

Description: This paper deals with predicting flow accumulation, drainage class, and soil and vegetation type within small headwater catchments (

Description: Freeze-thaw and flooding of usually well-drained soils occur in the spring in the prairie and boreal regions of Canada. We studied the impact of these conditions on nitrogen leaching in a Black Chernozemic soil (Udic Boroll). Soil samples, subjected to different treatments, were incubated for 12 wk in the laboratory and leached every 2 wk with 0.001 M CaCl2 solution. The cumulative leaching loss of total N (mg kg−1 soil) was reduced by freeze-thaw (76.0), flooding (41.4) and a superimposition of the two treatments (28.8) compared to the control (109). All treatments affected the distribution of the forms of N leached. The total loss of water soluble organic N (SON) and ammonium-N was in the order of flooded 〉 flooded-freeze-thaw 〉 freeze-thaw = control. In the leachates from the flooded treatments, SON accounted for 71.5–77.4% of the total N leached. Nitrate- and nitrite-N dominated the total leachable N in the unflooded treatments following an order of control 〉 freeze-thaw 〉 flooded = flooded-freeze-thaw. During the incubation, the Eh of the flooded soils decreased from 344 to −46 mV, compared to a variation in Eh from 355 to 301 mV for the unflooded soils. The maximum rate of leaching of organic nitrogen from the flooded treatment (0.53 mg N kg−1 d−1) coincided with a sharp decrease in Eh, from 131 to 42 mV. It is concluded that climatic events will have a significant impact on the dynamics of soil nitrogen. Flooding, in particular, may promote the loss of N in water soluble organic matter. Key words: Flooding, freeze-thaw, organic and inorganic nitrogen leaching, redox potential

Description: Containerized jack pine (Pinus banksiana Lamb.) seedlings were planted in 10 paired slash-pile-burn and control plots established on a recent clearcut in north eastern Ontario to assess early impacts of intensive fire on soils and plant growth and nutrition. Root zone soil and seedlings were sampled one growing season after planting. The control seedlings exhibited modest growth without gain in N content, indicating reliance on internal nutrient reserves for growth on this low-fertility site. Slash-pile burning reduced seedling mortality, and markedly increased height, rootcollar diameter, and biomass growth, as well as uptake of N, P, K, Ca and Mg. The response was attributed to greatly improved soil fertility following fire, characterized by increased pH, extractable NO3- and NH4+ , available P, and exchangeable K, Ca and Mg. Significant correlations between corresponding soil tests and seedling nutrient composition indicated that laboratory extractions effectively reflected nutrient availability to plants. The highest correlations were associated with N. Vector diagnosis identified N as the most limiting nutrient constraining growth on the burns, even though base cation increases (mainly from ash) were relatively larger than extractable N in the soil. These early responses in soils and plants to intensive fire may have long-term effects on plantation development. Key words: Slash pile, prescribed fire, soil fertility, seedling nutrition

Description: Soil solutions from four salt-affected soils in Alberta were extracted by immiscible displacement from field moist soils and saturated pastes after air-drying to examine the implications of using saturated paste extracts as a proxy of soil solutions. Solutions ranged in pH from 7.8 to 10.6 and in electrical conductivity (EC) from 6 to 45 dS m−1. Sodium dominated the cation suite, with Mg and K concentrations varying by several orders of magnitude between sites. Calcium was the major cation in lowest abundance at all sites. Sulfate was the predominant anion. Phosphorus concentrations ranged from 1 to 247 ppm. Considerable variation was seen between the properties of saturated paste extracts and immiscibly displaced solutions, with the saturated paste extracts having lower conductivities and Na, Mg, K and anion concentrations. The differences in composition between the two extraction methods resulted in differences in ion speciation, SAR and ESP values and mineral stabilities. Saturation indices for evaporite minerals were poor predictors of minerals formed in evaporated soil solutions. It was also found that even in chemically similar solutions, different minerals precipitated, and therefore the prediction of evaporite mineral formation from extracted soil solutions is not recommended. Key words: Salinity, saturated paste extracts, soil solutions, evaporites, mineral stability

Description: Concentrations of Ca, Mg, K, Na, Al, Fe, Mn, and Si extractable with 1 N ammonium chloride (NH4Cl, pH 4.5) and 1 N ammonium acetate (NH4OAc, pH 4.5) were determined for forest soil samples as follows: (1) before drying, and (2) at several time intervals after air-drying (1, 5, 11 and 14 wk). Values for CEC were obtained for the same samples by determining (1) the sum of cations (Al3+, Ca2+, Mg2+, K+, Na+, Fe3+, and Mn2+) in the extracts [denoted [Formula: see text] and [Formula: see text]], and (2) the amount of ammonium retained by the soil samples against water washing [denoted CEC(NH4OAc) and CEC (NH4Cl)]. The soils used in this investigation were taken from four New Brunswick upland forest sites (two sugar maple sites, one mixed wood site, and one spruce site). It was round that (1) extractable Mg, K, Na, and Mn levels were generally not affected by drying, storing, and type of extradant; (2) extractable Al and Fe levels increased immediately after drying; (3) NH4OAc-extracted Al, Fe, and Si exceeded NH4Cl-extracted Al, Fe, and Si; (4) extracted Al and Fe levels tended to drop after 11 wk of storage; (5) small drying effects were also noticed for NH4Cl-extracted Ca; (6) CEC(NH4OAc) and CEC(NH4Cl) values decreased with increasing time of storage; this effect was noticed most for soil samples with high levels of organic matter (Ah, Ahe, Bm, Bf, and Bfh), and was noticed least for sod samples taken from leached horizons (Ae) and subsoil horizons (BC and C); (7) in some cases, storage time increased CEC(NH4OAc) in subsoils; (8) values for [Formula: see text] remained fairly independent or increased slightly with storage time and were closely related with CEC(NH4Cl) values obtained with non-dried samples; (9) values for [Formula: see text] did not relate well with CEC(NH4OAc) and CEC(NH4Cl). Differences for extractable Al were likely due to Al complexation by acetate ions. Drying effects on extractable Al and Fe (and possibly Ca) were likely due to drying-induced fragmentation of soil organic matter. Drying and storage effects on CEC(NH4OAc) and CEC(NH4Cl) were likely due to (1) water-washing and related loss of organic matter, and (2) sensitivity of subsoil minerals to air exposure. Apparent drying and storage effects on CEC were most noted with [Formula: see text] and were least noted with [Formula: see text]. Key words: Cation exchange capacity, ion exchange, drying, storage, ammonium acetate, ammonium chloride extractions

Description: There exists a need (i) to test, whether equal or better cereal yields could be obtained using cropping systems which rely on renewable resources rather than on fertilizer nitrogen; and (ii) to discover the condition of the soil resource under these systems.The long-term cropping systems on a Gray Luvisol at Breton were studied. They included: (i) an agro-ecological 8-yr rotation (AER), established in 1981, which involved addition of both fababean green manure and manure from livestock fed with forages and fababeans grown in the rotation: (ii) a continuous grain (barley) system (CG), with fertilizer N at 90 kg ha−1 y−1, established in 1981; (iii) a classical Breton 5-yr rotation (CBR) involving forages and cereals, with no return of crop residues or manure, established in 1930. Mean barley yields were 16–19% higher in the AER (P ≤ 0.05) than in the CG system, and yield on either was about double that of the CBR. Within 9 yr, there was evidence of increased total C, N, and P; available N, P and K, CEC; microbial biomass, microbial respiration; and counts of bacteria, fungi, and mycorrhizae in the AER compared with the CG system.We conclude that biological fixation of N by legumes can be used as the sole source of N for barley production on Luvisolic soils of low fertility such as the Breton loam, without sacrificing yield or soil quality. Barley yields in the AER (38% of the rotation time) exceeded those of barley grown under continuous cereal cropping. The soil resource was maintained or improved during a 10-yr period under AER compared to the CG or CBR systems. Further research is needed to discover the mechanisms involved in regulating biological activity and availability of plant nutrients other than N in the AER system. Key words: Barley, Breton loam, cropping systems, Gray Luvisol, soil quality, fababeans

Description: Improving efficient use of applied nutrients in crop production is a desirable agronomic, economic, and environmental goal. Field experiments with corn (Zea mays L.) were carried out at two sites with contrasting soil textures in southwestern Quebec from 1988 to 1990. Objectives were to establish an optimum N fertilization rate for grain production, and to study fertilizer N use efficiency on a Chicot sandy clay loam (Grey Brown Luvisol) and a Ste. Rosalie clay (Humic Gleysol). Under favourable heat units and rainfall, yields of grain corn were quadratic functions of fertilizer N rates on both soils. Maximum grain yields of corn were calculated to require from 300 to 350 kg N ha−1 fertilizer application. However, large amounts of N fertilizer at both 285 kg ha−1 and 400 kg ha−1 were not recovered by the crop. Optimum economic grain yields at a price ratio of 10:1 N:grain were found at 273 kg N ha−1 on the Ste. Rosalie site in 1990, and 286 and 179 kg N ha−1 for 1989 and 1990, respectively, on the Chicot site. A normal fertilizer rate (170–44–141 kg N–P–K ha−1) and a high fertilizer rate (400–132–332 kg N–P–K ha−1) were used in 1989 and 1990 for 15N microplot experiments. Grain and stover fertilizer N recovery (FNR) varied with N rate and year from 9 to 58%. Favourable climatic conditions substantially increased crop yield, and thus crop FNR. Residual FNR the second year was less than 5% of the initial applied N. Key words:15N, grain yield, Zea mays L., nitrogen use efficiency, fertilization

Description: Organic matter can sorb P in acid soils through metal-organic matter-phosphate complexes. The pyrophosphate extractable Al and Fe and soil C contents were hypothetized to influence P partitioning in Ferro-Humic Podzols. Reaction of added P may be mitigated by adding lime or organic matter as dry swine manure (DSM) together with mineral P fertilizers. Three soils had 40 to 50 g kg-1 of soil organic matter (SOM) content, and 76 to 140 mmol (Al + Fe)pyro kg-1. A peaty soil phase had 200 g SOM kg-1, and 58 mmol (Al + Fe)pyro kg-1. Rates of monoammonium phosphate were 0, 27, 69, and 144 kg P ha-1 in a simulated fertilizer band. Rates of DSM and lime were 800 and 185–369 mg per 35 mL of soil, respectively. After 6 wk of incubation, soil P was fractionated sequentially into aluminium bound P (Al-P), iron bound P (Fe-P), and loosely bound P. Total P, desorbed P and organic P were determined in separate subsamples. A proportion of 79–92% of added P was recovered as Al-P and Fe-P in the three low SOM soils, compared to 51–61% in the high SOM soil. The DSM increased loosely bound P from 25 to 34% in the high SOM soil and from 4.8 to 5.9% in low SOM soils. With DSM, the proportion of desorbed P was much higher in the high (70%) than in low SOM (22%) soils. Compared to the non-amended treatment, lime showed no significant effect on any P fraction but desorbed P. The DSM increased P availability in the fertilizer band considerably more in the soil having the lowest (Al + Fe)pyro/C ratio. Key words: P fractionation, organic ligand, P sorption, fertilizer band

Description: The production and utilization of root-derived C is fundamental to the functioning of ecosystems. The objectives of this experiment were to quantify the amount of root-released C produced by two barley (Hordeum vulgare L.) cultivars, to evaluate the direct and indirect effects of shoot C, root C and root length on the root-released C and to quantify the kinetics of the decomposition of root-released C in soil for two barley cultivars. Seedlings of two barley cultivars, Abee and Samson, were cultured in nutrient solution for 20 d and then pulse-labelled with 14C for 5 d. Samson released more C than Abee during the entire experimental period. Root length had the greatest direct effect on root-released C for the two barley cultivars. Kinetics analysis of the decomposition of root-released C added to soil showed that the labile components of the added material was 87.3% for Abee and 74.4% for Samson with half-lives of 4.3 d and 4.5 d, respectively. The half-lives of the resistant components of the root-released C added to soil and microbially-derived material were 37.7 d for Abee and 29.6 d for Samson, respectively. The amount of root-released C and its decomposition rate in soil varied with cultivars used. Key words: Root-released C, path analysis, direct effect, indirect effect, 14C, decomposition, Typic Cryoboroll

Description: A study was conducted on three Manitoba soils (Marquette heavy clay, Fortier silty clay loam, and Souris loamy sand) with the objectives of: (a) assessing the effects of contrasting tillage systems on various soil physical properties; and (b) relating root penetration of cereals to these properties. The zero tillage (ZT) and conventional tillage (CT) treatments had been established between 3 (Marquette and Souris) and 10 (Fortier) years prior to the initiation of the study. Penetrometer resistance (PR), bulk density (BD) and pore size distribution (PSD) were measured at various depths and times during two growing seasons. The effects of tillage systems on soil properties were generally small, particularly in the poorly structured Souris loamy sand. PR in the top 10 cm of soil tended to be higher under ZT than under CT. PR varied markedly with time and was closely related to changes in soil water content. The proportion of macropores (〉 100 μm in diameter) near the soil surface tended to be higher under ZT than under CT. There was no evidence of any detrimental effect of poor aeration on the final root penetration profiles of wheat. The proportion of roots penetrating the soil was inversely related to PR. Soil strength critical for root penetration was determined to be 2 MPa and was independent of soil type. In most situations, however, roots were able to grow into soil with mechanical impedance greater than 2 MPa, possibly by making use of biochannels and spatial and temporal heterogeneity in the soil structure. Key words: Wheat, barley, zero tillage, conventional tillage, root penetration, penetration resistance

Description: The thick folic (mainly upland forest) materials (〉 40 cm of accumulated organic material) that occur in the Coastal Western Hemlock Biogeoclimatic Zone in British Columbia have not been described with regard to the spatial interrelationships of the soil constituents in context with the chemical composition of the different horizons. Micromorphological assessment and solid-state 13C NMR were used to characterize the accumulated folic materials from a Lignic Folisol (northern Vancouver Island), Histic Folisol (Prince Rupert, BC) and a Humic Folisol (Queen Charlotte Islands, BC). Micromorphology provided information on the spatial relationships of the soil constituents and 13C NMR provided data on the chemical components of the folic materials. Soil faunal activity, primarily from mites, was the dominant soil-forming process observed in the organic horizons of the Folisols, being especially prominent in the Lignic Folisol with the breakdown of woody materials. Solid state 13C CPMAS NMR spectra facilitated distinguishing three main types of horizons: (1) Horizons derived from accumulated residues (L, Fr, and Hr) showing higher carbohydrate-like C and O-alkyl C values and lower total aromatics; (2) Horizons with advanced decomposition (Hr2, Oh1, and Hd) which were higher in alkyl C; and (3) Horizons derived from ligneous material (Fw and Hdw) where carbohydrate-like C was less than total aromatic C. Implications for adequate nutrient content and forest growth were inferred from the observed micromorphology and chemical composition of the folic materials. Key words: Folisol, forest soils, micromorphology, 13C NMR, faunal activity

Description: A 2-yr study was conducted to investigate the effects of application date, landscape position and a urease and nitrification inhibited formulation of urea on the efficiency of fall-banded N fertilizer under Manitoba conditions. To date, no studies have investigated how these factors interact to influence the efficiency of fall-banded N in western Canada. The effects of landscape position were apparent at three of the four sites, with significantly greater grain yields, straw yields and total recovery of N in the high landscape positions than in the low landscape positions. In the high landscape positions, there were no significant differences in crop response or recovered N among application dates in the fall and spring. However, in the low landscape positions, grain yields, grain yield increases and apparent recovered fertilizer N in the aboveground portion of the crop and in the soil (0–120 cm) were significantly greater for spring and late fall applications, when compared with early and mid-fall applications. At one site in the first year of the study, early fall-banded N with the urease and nitrification inhibitors produced greater increases in grain yield than early fall-banded N without the inhibitors in the low landscape positions. However, overall there was little agronomic benefit to the use of the additives, as there were few significant differences in crop yields or N uptake by the crop with the inhibitors than without, in either year or landscape position. The results demonstrate that selection of suitable timing for application of fertilizer N to optimize crop yields is much more critical for poorly drained areas within a field, or for poorly drained fields, than for better drained land. Key words: Fall-banded N, spring-banded N, landscape position, N-(n-butyl) thiophosphoric triamide (NBPT), Dicyandiamide (DCD), wheat (Triticum aestivum)

Description: Soil N supply is an important contributor of N to crop production; however, there is a lack of practical methods for routine estimation of soil N supply under field conditions. This study evaluated sampling just prior to topkill of whole potato plants that received no fertilizer N as a field bioassay of soil N supply. Three experiments were performed. In exp. 1, field trials were conducted to test if P and K fertilization, with no N fertilization, influenced plant biomass and N accumulation at topkill. In exp. 2, plant N accumulation at topkill in unfertilized plots was compared with mineral N accumulation in vegetation-free plots. In exp. 3, estimates of soil N supply were obtained from 56 sites from 1999 to 2003 using a survey approach where plant N accumulation at topkill, and soil mineral N content to 30-cm depth at planting and at tuber harvest were measured. Application of P and K fertilizer had no significant effect on plant N accumulation in two trials, and resulted in a small increase in plant N accumulation in a third trial. Zero fertilizer plots, which can be more readily established in commercial potato fields, can therefore be used instead of zero fertilizer N plots to estimate soil N supply. In exp. 2, estimates of soil N supply were generally comparable between plant N accumulation at topkill and maximum soil NO3-N accumulation in vegetation-free plots; therefore, the plant bioassay approach is a valid means of estimation of plant available soil N supply. Plant N accumulation at topkill in exp. 3 averaged 86 kg N ha-1, and ranged from 26 to 162 kg N ha-1. Plant N accumulation was higher for sites with a preceding forage crop compared with a preceding cereal or potato crop. Plant N accumulation was generally higher in years with warmer growing season temperatures. Soil NO3-N content at harvest in exp. 3 was less than 20 kg N ha-1, indicating that residual soil mineral N content was low at the time of plant N accumulation measurement. Soil NO3-N content at planting was generally small relative to plant N accumulation, indicating that soil N supply in this region is controlled primarily by growing season soil N mineralization. Use of a plant bioassay approach provides a practical means to quantify climate, soil and management effects on plant available soil N supply in potato production. Key words: Solanum tuberosum, nitrate, ammonium, N mineralization, plant N accumulation

Description: Forest landings are areas located adjacent to haul roads where harvested trees that were skidded from the cutblock are processed and loaded onto trucks. Soils on landings are often excessively compacted by heavy timber harvesting machinery and may take many years to recover from such disturbance. This study examined soil properties and tree growth on unrehabilitated landings (with and without natural regeneration) and adjacent naturally regenerated clearcuts in the central interior of British Columbia (BC), 23 yr after landing construction. Landings (both with and without natural regeneration) had less favorable conditions for tree growth than did clearcuts, including significantly greater surface soil bulk density and mechanical resistance (on some dates) and lower total porosity and concentrations of C and N. Landings without natural regeneration had the least favorable soil conditions, which may account for the lack of natural regeneration. Lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) growing on portions of the landings did not differ in height from those growing in adjacent clearcuts. Site index, as estimated using the growth intercept method, did not differ between naturally regenerated landings (21.7 m) and clearcuts (22.0 m), suggesting that the soils may be equally capable of supporting productive forests. Key words: Forest soil disturbance, soil mechanical resistance, soil productivity, soil water content, natural regeneration

Description: Conservation tillage (CT) for potato crop land has been increasing in Atlantic Canada, but producers are concerned that fields managed in this way may be wet, slow to warm in spring, have increased debris at harvest, exhibit higher soil compaction and result in reduced yield. The objective of this study was to compare the effects of four tillage practices on potato yield, soil properties and weed growth over a 3-yr period. The four tillage practices were: (1 ) conventional autumn mouldboard plowing followed by spring secondary tillage; (2) spring mouldboard plowing followed by secondary tillage; (3) autumn chisel plowing followed by spring secondary tillage; and (4) spring CT. Tillage practices significantly affected soil water content (at both the 0- to 15-cm and 15- to 30-cm soil depths) with CT generally showing a greater soil water content prior to spring tillage in comparison to the other treatments. Soil temperature (at the 2- to 5-cm soil depth) prior to spring tillage was not influenced by tillage differences. Conservation tillage increased soil compaction at the 10- to 30-cm soil depth, but not to a level considered detrimental to root growth. Tillage treatments had no effect on amount of soil clods and plant debris passing over the harvester. Potato yield (range of 43 to 51 Mg ha-1) and quality were not adversely influenced by tillage practices. There were few treatment effects on individual weed species or groupings of annual, perennial and total weeds. Overall, CT can be a viable management alternative to conventional tillage because this practice does not negatively affect field management, potato yield, or soil quality. Key words: Conservation tillage, residue management, potato, soil temperature, soil moisture, tillage methods

Description: Agroclimatic indices (heat units and water deficits) were determined for the Atlantic region of Canada for a baseline climate (1961 to 1990 period) and for two future time periods (2010 to 2039 and 2040 to 2069). Climate scenarios for the future periods were primarily based on outputs from the Canadian General Circulation Model (GCM) that included the effects of aerosols (CGCMI-A), but variability introduced by multiple GCM experiments was also examined. Climatic data for all three periods were interpolated to a grid of about 10 to 15 km. Agroclimatic indices were computed and mapped based on the gridded data. Based on CGCMI-A scenarios interpolated to the fine grid, average crop heat units (CHU) would increase by 300 to 500 CHU for the 2010 to 2039 period and by 500 to 700 CHU for the 2040 to 2069 period in the main agricultural areas of the Atlantic region. However, increases in CHU for the 2040 to 2069 period typically varied from 450 to 1650 units in these regions when variability among GCM experiments was considered, resulting in a projected range of 2650 to 4000 available CHU. Effective growing degree-days above 5°C (EGDD) typically increased by about 400 units for the 2040 to 2069 period in the main agricultural areas, resulting in available EGDD from 1800 to over 2000 units. Uncertainty introduced by multiple GCMs increased the range from 1700 to 2700 EGDD. A decrease in heat units (cooling) is anticipated along part of the coast of Labrador. Anticipated changes in water deficits (DEFICIT), defined as the amount by which potential evapotranspiration exceeded precipitation over the growing season, typically ranged from +50 to −50 mm for both periods, but this range widened from +50 to −100 mm when variability among GCM experiments was considered. The greatest increases in deficits were expected in the central region of New Brunswick for the 2040 to 2069 period. Our interpolation procedures estimated mean winter and summer temperature changes that were 1.4°C on average lower than a statistical downscaling procedure (SDSM) for four locations. Increases in precipitation during summer and autumn averaged 20% less than SDSM. During periods when SDSM estimated relatively small changes in temperature or precipitation, our interpolation procedure tended to produce changes that were larger than SDSM. Additional investigations would be beneficial that explore the impact of a range of scenarios from other GCM models, other downscaling methods and the potential effects of change in climate variability on these agroclimatic indices. Potential impacts of these changes on crop yields and production in the region also need to be explored. Key words: Crop heat units, effective growing degree-days, water deficits, climate change scenarios, statistical downscaling, spatial interpolation

Description: Nitrogen management strategies that enhance fertilizer use efficiency and maximize profitability in corn require a rapid and accurate method to determine the crop N needs of current hybrids. The objective of this study was to evaluate the potential of a portable chlorophyll meter for predicting N fertilizer requirements for corn grown under varying levels of N availability. Several crop management treatments were imposed in an attempt to create conditions ranging from low N availability (oily food waste application in spring and fall, application at different rates in spring) to high N availability (continuous fertilized corn, winter wheat cover crop). Different corn hybrids were sown at different sites (21 site yr) and varying N fertilizer application rates were applied. Chlorophyll meter readings (CMR) were taken at the 5th to 6th leaf stage (V6) using a SPAD-502 chlorophyll meter. The crop management treatments, corn hybrids and their interaction significantly affected the chlorophyll meter readings. A high inverse correlation between chlorophyll meter readings and maximum economic rate of nitrogen (MERN) was observed (r = −0.87). The main new and unique aspect of our research is the development of a linear model for using chlorophyll meter measurements to make N fertilizer recommendations (MERN = 348.47 − 8.5304 × CMR ) for corn production under varying degrees of N availability in Southern Ontario. Key words: Chlorophyll meter, soil organic carbon, nitrogen application

Description: The amount of available nitrogen in fresh and composted manures is required to adjust inorganic fertilizer applications for crops when using manures and composts. Corn (Zea mays L.) plants were grown for 8 wk at temperatures of 17–27 °C and 12–18 °C in soil amended with two rates of fresh and composted solid beef cattle manure. Apparent N uptake of corn grown in soil amended with fresh solid beef cattle manure, composted beef cattle manure and (NH4)2SO4 at the higher temperature was 2, 8, and 36%, respectively, during this 8-wk period. Nitrogen uptake by corn in fresh solid beef cattle manure-amended soil at low temperature was affected by factors other than N availability. A 12-wk laboratory experiment was performed in which 15NH4+ was added to fresh and composted manure-amended soil to determine the fate of the inorganic N in the manure and to measure N mineralization rates. Net immobilization of inorganic N occurred with all manures; however, after 3 wk, net mineralization occurred with the solid and composted beef cattle manure. Immobilization of 15N continued with all manure amendments as a result of mineralization-immobilization turnover. The amount of unrecovered 15N after 12 wk was 10.5, 2 and 1% of the added 15N in soil amended with solid beef cattle manure, composted beef cattle manure and manure composted with bark, respectively. Key words: Composted manure, nitrogen availability, 15N, immobilization, remineralization, temperature

Description: Barley (Hordeum vulgare L.) and oat (Avena sativa L.) crops are grown as feed grains by Newfoundland (NL) dairy farmers. The cereals are either grown as monoculture or intercropped with field pea (Pisum sativum L.) with or without N fertilization. Two experiments were conducted in both 2000 and 2001 to evaluate the shoot-to-root (S:R) weight ratios and root biomass in these production systems. Experiment 1 involved monocultures of pea sown at 150 kg ha-1, and barley and oat each sown at 170 kg ha-1. For pea-barley and pea-oat intercrops, pea was sown at 150 kg ha-1 and each cereal component was sown at either 85 and 170 kg ha-1. The seven treatments were referred to, respectively, as pea150, barley170, oat170, pea150-barley85, pea150-oat85, pea150-barley170, and pea150-oat170. Experiment 2 evaluated factorial combinations of two barley seeding rates of 107 kg ha-1 (low) and 157 kg ha-1 (high) and three N rates (0, 30 and 60 kg ha-1) applied at Zadok’s Growth Stage (ZGS 30). Root biomass was sampled from soil (30-cm depth) and determined at about the anthesis stage of oat and barley and the shoot biomass at maturity (ZGS 90). In exp.1, the S:R ratios of oat170 and pea150-oat85and pea150-oat170 ranged from 8.1 to 8.8 and were lower than barley170, pea150, pea150-barley85and pea150-barley170 which ranged from 10.0 to 12.5. Barley170 had the highest root biomass of 835 kg ha-1 followed by pea150-barley170 (745 kg ha-1) and pea150-oat170 (765 kg ha-1). Intercropping pea with cereals increased root biomas s by 31% for pea150-barley85and 48% for pea150-oat85compared to pea150. However, root biomass increased by 109% for pea150-barley170 and 104% for pea150-oat170, indicating that the cereal component of the intercrops contributed more to the root biomass than the pea at the higher seeding rate of the cereal crop. In exp. 2, the 0 kg N ha-1 rate produced the lowest S:R ratios irrespective of the barley seeding rate. When N was applied, both the shoot biomass and root biomass appeared to be increased at the high barley seeding rate. The feed grain production practice in Newfoundland could affect root biomass production in soil. High cereal seeding rates in either monoculture and intercrop systems are required to maximize root biomass production and therefore increase C inputs into the soil. Key words: Shoot-to-root (S:R) ratios, root biomass, intercrops, barley, oat, pea, seeding rate

Description: An IPCC-based Carbon Monitoring System (CMS) was developed to monitor soil organic C stocks and flows to assist New Zealand to achieve its CO2 emissions reduction target under the Kyoto Protocol. Geo-referenced soil C data from 1158 sites (0.3 m depth) were used to assign steady-state soil C stocks to various combinations of soil class, climate, and land use. Overall, CMS soil C stock estimates are consistent with detailed, stratified soil C measurements at specific sites and over larger regions. Soil C changes accompanying land-use changes were quantified using a national set of land-use effects (LUEs). These were derived using a General Linear Model to include the effects of numeric predictors (e.g., slope angle). Major uncertainties a rise from estimates of changes in the areas involved, the assumption that soil C is at steady state for all land-cover types, and lack of soil C data for some LUEs. Total national soil organic C stocks estimated using the LUEs for 0–0.1, 0.1–0.3, and 0.3–1 m depths were 1300 ± 20, 1590 ± 30, and 1750 ± 70 Tg, respectively. Most soil C is stored in grazing lands (1480 ± 60 Tg to 0.3 m depth), which appear to be at or near steady state; their conversion to exotic forests and shrubland contributed most to the predicted national soil C loss of 0.6 ± 0.2 Tg C yr-1 during 1990–2000. Predicted and measured soil C changes for the grazing-forestry conversion agreed closely. Other uncertainties in our current soil CMS include: spatially integrated annual changes in soil C for the major land-use changes, lack of soil C change estimates below 0.3 m, C losses from erosion, the contribution of agricultural management of organic soils, and a possible interaction between land use and our soil-climate classification. Our approach could be adapted for use by other countries with land-use-change issues that differ from those in the IPCC default methodology. Key words: Soil organic carbon, land-use change, stocks, flows, measurement, modelling, IPCC

Description: Carbon dioxide (CO2) from soil respiration is the focus of many ecosystem-atmosphere studies. However, due to the difficulty in obtaining measurements, there is a relative lack of information on the behavior of CO2 in the soil. This paper describes an accurate method that can be used in the field to measure CO2 concentration in small (10-cm) samples of soil air using an infrared gas analyzer. Measurements on samples drawn by syringe from different depths are compared to those calculated using a simple steady-state model derived from the conservation equation for soil CO2 and Fick’s law of diffusion. The study site is a second growth coastal temperate Douglas-fir forest plantation (53 yr old) located on the eastern slope of Vancouver Island, Canada. Measurements of CO2 concentrations were obtained from two locations at six soil depths between 0.02 and 1 m at various times of the year in 2000 and 2001. The vertical profiles of CO2 concentrations generally had similar shapes throughout the year although there was considerably more short-term variability in the shallow layers. Below-ground CO2 concentrations were higher during summer and decreased during the winter. Non-zero CO2 concentration gradients between the 0.5- and 1-m depths suggested some CO2 production below the 1-m depth. By matching modelled CO2 concentrations with measured values and using measured CO2 efflux, we used the model to determine the CO2 production profile. Calculations of CO2 production profiles indicated that more than 85% of the CO2 efflux from this forest soil originates at depths shallower than 30 cm. Key words: Soil carbon dioxide, CO2, soil respiration, steady-state model

Description: Increasing concern about the need to provide high-quality food with minimum environmental impact has led to a new interest in crop rotations as a tool to maintain sustainable crop production. We review the role of rotations in the development and preservation of soil structure. After first introducing the types of rotations in current practice and their impact on yield, we assess how soil and crop management in rotations determines soil structure, and in turn how soil structure influences crop growth and yield. We also briefly consider how soil structure might contribute to other beneficial effects of rotations, namely nutrient cycling and disease suppression. Emphasis is given to the influence of crop choice and, where relevant, interaction with tillage system and avoidance of compaction in the improvement and maintenance of soil structure. Crop rotations profoundly modify the soil environment. The sequence of crops in rotation not only influences the removal of nutrients from a soil, but also the return of crop residues, the development and distribution of biopores and the dynamics of microbial communities. These processes contribute to the development of soil structure. We have identified areas where further research is needed to enable the potential benefits of rotations in the management of soil structure to be fully exploited. These include: improved quantitative linkages between soil structure and crop growth, the consequences to soil structure and nutrient cycling of crop residue incorporation, developing natural disease suppression, amelioration of subsoils by crop roots, the fate of carbon deposited by plant roots in soil and the fate of organic nitrogen in soil. Key words: Organic farming, microbial activity, nutrient cycling, compaction, disease suppression, soil structure

Description: Illuviated mineral horizons (Bf) from a Podzol on the Precambrian Shield, Ontario, Canada were collected, placed in columns and treated with distilled water, cation amended water, acidified water or cation and acid amended water over a 4-mo period. While the cation treatment had little effect relative to the control, the acid treatment removed large quantities of Al, Si and base cations. The source of the leached Al was primarily (~ 70%) dithionite–citrate–bicarbonate (DCB) extractable Al, apparently some form of amorphous gibbsite. Organic Al (pyrophosphate extractable) contributed only about 20%. However, even more pronounced was a major within-column migration of oxalate extractable Al–Si, perhaps allophane or imogolite, which was leached from the top of the acidified columns and precipitated below. The weathering of primary minerals and possibly interlayer Al in vermiculite contributed little to the leaching of Al from the acidified columns. Key words: Acid, weathering, Podzol, aluminum, silica

Description: With the reduction in S inputs through atmospheric deposition and high analyses fertilizers, soil organic S will become a more important source of S to crops. Sulfur mineralization in 20 meadow soils was investigated using a long-term aerobic incubation and a greenhouse bioassay with alfalfa (Medicago sativa L.). The cumulative S mineralization (Sm) was linear with time for 13 soils whereas 7 soils showed an exponential phase over the first 10 wk followed by a linear release phase. Podzolic soils dominated the latter group. The data were described by an incremental zero-order model where an initial flush was accounted for. The total amount of mineralizable S (Sm), the amount of S mineralized in the first 1.4 wk (Se), the S mineralization potential (So) and the rate constant (k) were all very closely correlated to the N mineralization potential and to the amount of N mineralized in the first 1.4 wk of incubation (r = 0.64–0.85; P 

Description: The practice of planting potatoes (Solanum tuberosum) in rows and hilling the plants at some stage of growth has been universally adopted. Using a rainfall simulator and runoff-erosion plots (0.9 m wide × 1 m long), the effects of hilling on runoff, infiltration, and soil loss were examined on an Orthic Dystric Brunisol. Tests of the rainfall simulator revealed that variations in operating pressure (36.5–62.1 kPa) and soil slope conditions (0–15%) did not significantly (P 

Description: This paper presents information on pedogenic processes, weathering status and geochemical evolution of ultramafic soils at three areas in southwestern British Columbia characterized by climatic conditions ranging from relatively wet–cool to relatively dry–cool. The soils of the Coquihalla serpentine belt have Podzolic profiles that resulted from intense weathering in a moist environment. The Tulameen area has a moderately dry climate, and Brunisolic soils have developed in serpentinized peridotite and dunite. Brunisolic soils with composite profiles of tephra overlying serpenite developed in a dry environment at the Shulaps area. We investigated the weathering status of five soils using a variety of chemical and mineralogical techniques. Chlorite and mica weathering was indicated by XRD analysis of clay fractions for the Podzolic soils at the Coquihalla area. Serpentine dissolution was also indicated by geochemical analysis of these upland soil profiles. Weathering and leaching depleted Mg from B horizons relative to parent materials. Chromium accumulated in B horizons of the soils, and was associated with high levels of Fed. The distribution of total and extractable Ni and Co indicated that these elements were transported to the C horizons in all but the driest environments. Redistribution of Mn also occurred, but to a lesser extent. The distribution patterns of Cr, Mn, Co, and Ni were useful indicators during the early stages of ultramafic pedogenesis. Key words: Serpentine, ultramafic rocks, mineralogy, soil processes, trace minerals

Description: The land around Bahía Blanca, Argentina, has been farmed intensively for six decades. We report the concentrations of a number of organochlorine pesticides (DDT, dieldrin, endrin, heptachlor epoxide and lindane), and of DDT metabolites (DDD + DDE) in three different layers (0–5, 5–10 and 10–20 cm) of the soils in 44 fields of eight farms that have been devoted to horticulture for periods ranging from 15 to 60 yr. In spite of the horticultural use of these substances having been banned for the past 13–35 yr, high concentrations were found – up to nearly 12 mg kg-1 for DDT + DDD + DDE, 17 mg kg-1 for dieldrin, 4 mg kg-1 for endrin, 7 mg kg-1 for heptachlor epoxide and 0.8 mg kg-1 for lindane. The highest concentrations of DDT, dieldrin, endrin and heptachlor epoxide were found on the oldest farms, the highest levels of DDD + DDE on middle-aged farms (35–40 yr), and the hi ghest levels of lindane on 15–40-year-old farms that had rather lower soil pH than the older farms. Concentrations invariably decreased slightly with increasing depth, and for DDT, dieldrin and heptachlor epoxide they exhibited significant positive correlation with soil organic matter content. Principal components analysis confirmed the distinguishability of three groups of analytes: one comprising DDT, dieldrin, endrin and heptachlor epoxide associated with higher soil organic matter and clay contents; and two singletons, DDD + DDE associated with higher pH and lindane. We conclude that these pesticides have very limited mobility in these semiarid alkaline soils. Key words: Organochlorine, semiarid soils, horticulture, depth variation.

Description: Pore size, distribution and continuity are important characteristics for the exchange and storage of air and water in artificial mixes. Saturated hydraulic conductivity (Ks) measurements can be used to obtain such a characterization. However, two difficulties are encountered when using Ks in potting media. First, the validity of Ks may be limited because it may not apply in media composed of coarse material or peat. Second, the structure of peat substrates is very sensitive and in situ measurements of potted peat substrates (i.e. measurements made directly in the pots) should be carried out to avoid any disruptive effect due to handling. Such a measurement, when made in pots, may require the evaluation of the water flux reduction resulting from the container outflow configuration. The objectives of this study were therefore to check the validity of Darcy’s law for peat substrates and to propose an approach for estimating the saturated hydraulic conductivity from flow measurements made in nursery containers. For three different substrates, water flow in artificial mixes followed Darcy’s law for hydraulic gradients ranging from 1.1 to 1.6 cm cm−1. Experimental results showed that the measured fluxes in 5-L nursery container filled at five different substrate heights (9, 11.5, 14, 16.5 and 19 cm) with laterally located drainage holes were significantly different from those measured in pots with the bottom removed (therefore equivalent to measurement currently made in cylinders) at P = 0.0022. Fluxes in containers with bottoms removed were 7–31% higher than in intact pots. Water flux measurements may therefore need to be corrected for this flux reduction in order to accurately estimate hydraulic conductivity from flow experiments run in pots. A correction factor based on the results obtained from a finite difference model was derived and calibrated. Then, this correction factor was used to convert flux measurements made in pots with lateral holes into equivalent flux that would have been obtained had the pot had an open bottom. After correction, no significant flux reductions were found between pots with open bottoms and pots with lateral holes (P = 0.55). A correction factor estimated from Laplace’s equation, once calibrated, can therefore be applied to flux measurements obtained from pots to obtain estimates of Ks of undisturbed potted media. Key words: Hydraulic conductivity, peat substrates, container

Description: The spatial distribution of soil properties, erosion and crop yield was studied along a cultivated transect and an adjacent transect in virgin grassland. The mapping unit was in hummocky moraine in the Dark Brown soil zone of central Saskatchewan. Erosion was affected by an interaction between elevation and surface curvature which affected the spatial and statistical distribution of soil properties and yield in the landscape. For the cultivated transect, percent sand was higher on knolls than in depressions, furthermore several soil properties were nonlinearly related to elevation. Decreases in grain yield on convex or planar lower slopes were correlated with erosion and high carbonate contents. Carbonate concentrations were high in lower slope positions in the cultivated transect, particularly at a relative elevation of 1 m, and appeared to be an important soil property influencing yield. Future studies of soil properties and yield on hillslopes may require careful evaluation of both elevation and microtopography in order to elucidate the effects of erosion. Key words: Erosion, yield, spatial variability, topography

Description: The assessment of the health and environmental impacts of metal contamination in soils is complicated, and in different ways than is the assessment of many other contaminants. One of the foremost problems is that the metals are often relatively immobile, so that it is necessary to verify predictions of mobility and impact far into the future. One approach is to seek analogue information: information from studies that may not have set out to measure attributes related to metal behaviour, but that none the less provide useful insights. One example would be the information on the mobility of natural clays and pedogenic metals such as iron and aluminum in soils. It is well accepted that clay particles will move downward in soils; what is less commonly inferred is that any contaminants associated with the clays will also move downward. For mobility of some metals, this may be a dominant process. Similarly, bioturbation has proven to markedly outpace leaching for many metals. This paper considers analogues related to cesium from bomb-fallout and Chernobyl, other natural radionuclide inputs to the soil, soil pedogenesis, pollen and non-metal industrialage inputs, ancient metal works, and soil fertility management. Related to biological transfers and toxicity, it considers analogy among elements an d among biota, and analogy to ecotoxicology of metals to freshwater biota. Where possible, limiting values for parameters of assessment models have been derived. Key words: Terrestrial, leaching, mobility, ecotoxicity, assessment

Description: The risk of surface-water contamination by herbicides is greatest following application to cropland when the active ingredients are at the maximum concentration and the soil is the most vulnerable to erosion following cultivation. This study determined the magnitude of surface runoff losses of herbicide and nutrients at, and subsequent to, application. The first of three weekly 10-min, 2.6-cm rainfalls were simulated on triplicated 1-m plots (a set) on which corn had been planted and the herbicide (metolachlor/atrazine, 1.5:1.0) and fertilizer (28% N at 123 kg ha−1) had just been applied. Identical simulations were applied to two other adjacent plot sets (protected from rainfall) 1 and 2 wk following herbicide application. Runoff (natural, simulated) was monitored for soil, nutrient and herbicide losses. Concentrations of total phosphorus in surface runoff water and nitrate N in field-filtered samples were not significantly influenced by the time of the rainfall simulation but exceeded provincial water-quality objectives. Atrazine and metolachlor runoff losses were greatest from simulated rainfall (about 5% loss) immediately following application. Subsequent simulated rainfall usually resulted in

Description: The influence of 40 years of red pine and Norway spruce growth on forest floor and soil nutrient status was examined in a well-replicated series of plantation blocks established on abandoned agricultural land. Concentrations of N, P, K and Ca, and mass of organic matter and all nutrients in the forest floor were higher under spruce than under pine. In the mineral soil, concentrations of exchangeable K and Ca were higher under spruce whereas Mg, extractable P and mineralizable N did not differ between the species. Forest floor pH was higher under spruce but mineral soil pH did not differ between the species. The soil characteristics reflected litter chemistry of the two species. Relative to pine, spruce foliage litter was consistently higher in nutrient concentration and had lower acidity and higher ash bases. The results are inconsistent with the reputation of Norway spruce as a species that strongly acidifies soils, an observation that may be the result of elevated levels of Ca and K in our soils relative to those in other studies where acidification has been observed. This research demonstrates that soil fertility can be altered significantly by tree species effects over the period of a single rotation. Key words: Forest soil fertility, plantation, acidity, forest floor, leaf litter

Description: In the past two decades, investigators have documented a decrease in total lead concentration and amount in upper soil horizons of forest soils following a reduction in the use of gasoline lead additives. In this study, we compare three data sets of lead isotopic ratios in forest soils from Sweden, Norway and the United States of America in order to formulate hypotheses relating to the factors that dictate lead distribution among horizons in Podzolic soils. A larger fraction of anthropogenic lead is seen at greater depths in the Swedish sites and in the southern sites from Norway then in the USA site. At present, only the time of onset of lead pollution appears to be related to the observed pattern. These observations could not have been made within any individual study but became clear when the three independent studies were examined together. Key words: Lead, soils, long distance transport, migration rates

Description: Changes in soil properties reflect the success or failure of reclamation practices on abandoned wellsites. We examined the effect on soil properties of four (0, 50, 100 and 150%) topsoil replacement depths (TRD) and five amendment treatments [compost, manure, wheat (Triticum aestivum L.) straw, alfalfa (Medicago sativa L.) hay, check] aimed at reclaiming three wellsites (Strathmore, Hesketh and Rosedale) in southcentral Alberta. TRD treatment differences were consistent across all wellsites, with 30 to 32% higher soil organic carbon (SOC) on the 150% TRD compared to the 0% TRD. Initially, the alfalfa treatment showed higher levels of nitrate-nitrogen (e.g., 26 mg kg-1 vs. 3 to 7 mg kg-1 for the other amendment treatments in the 15- to 30-cm depth at Strathmore in fall 1998), which was related to its rapid breakdown and mineralization of organic N. After 40 mo (June 1997-October 2000), the average amounts (n = 3 wellsites) of added C conserved near the soil surface were: compost (65 ±10% SE) 〉 manure (45 ±16% SE) 〉 alfalfa (28 ±11% SE) 〉 straw (23 ± 6% SE). Our results show that organic amendments play an important role in improving soil properties related to long-term productivity of reclaimed wellsites, especially where topsoil is scarce or absent. Key words: Wellsite reclamation, topsoil depth, organic amendments, soil quality

Description: Lupin (Lupinus albus L. ’Ultra’) was evaluated as a green manure crop the year preceding potato production on Prince Edward Island for 3 yr. One pass of tandem disc was used to incorporate lupin green manure on 1 September (early) or 1 October (late). Barley residue following combine harvest was also incorporated in the same way in early September. One treatment of lupin was left unharvested with no fall incorporation (none), and in another treatment of lupin the seed was fall harvested with no fall incorporation. All treatments were moldboard plowed the following spring. Potato (Solanum tuberosum L. ’Russet Burbank’) was planted with three rates of nitrogen (0, 50, and 200 kg ha−1) band applied. Tuber yield and tuber N content increased with increasing rates of N applications in all incorporation treatments. Following late incorporated lupin, potato had higher tuber yield at 0 N than following the early incorporated lupin, while both treatments were higher than barley. Potato petiole nitrate-N levels and the mean spring nitrate-N concentrations in the soil were lower following barley than following lupin, and generally lower following early compared to late incorporation of lupin green manure. These data indicate the time of fall incorporation of a legume can have a significant effect on the N response of a succeeding crop. Early fall incorporation can result in significant fall N mineralization and winter leaching. Research on N response after legumes in rotation should consider the impact of time and method of residue incorporation. Key words: Petiole nitrate-N, nitrate leaching, green manure

Description: The soil solution provides the majority of essential nutrients needed for plant growth. Obtaining this solution in situ presents logistic problems and therefore most results are obtained from air-dried soils, even though chemical properties of soils can be substantially modified by drying. Water-saturated extracts obtained from dried soils were tested for their efficiency to detect the effects of in situ fertilization with P-TSP, K-K2SO4 and Ca-Ca(OH)2 on the Ahe horizon of a maple stand. Results obtained with water-saturated extracts on dried soils were compared with those obtained from conventional (exchangeable) extraction on dried soils and to those obtained from extraction with a soil:water ratio of 1:5 on dried soils. A similar experiment comparing water-saturated extracts with the soil:water ratio of 1:5 was carried out using soils fertilized in vitro. The effects of fertilization were clearly evident with saturated extracts when these could be observed by conventional analysis. Furthermore, the saturated extract indicated potential toxicity of Al in relation to pH. For the same samples, the saturated extracts were more sensitive than the extracts with a soil:solution ratio of 1:5, especially with regard to element ratios not easily expressed by conventional analysis. The originality of this method rests on a combination of efficient centrifugation with a double bottom container, the convenience in the utilization of air-dried soils and the use of near water field capacity as a representative water content. Key words: Saturated extracts, fertilization, toxicity, maple stand

Description: The practice of placing granular Cu fertilizers with the seed of cereals and oilseeds has been expanding in western Canada mainly due to the high cost of applying the minimum suggested broadcast and incorporation rate of 3.5 kg Cu ha-1. The hypothesis made is that annual applications of small amounts of Cu in the order of 1 kg Cu ha-1 will satisfy the Cu requirement of a crop and, over a period of years, have the same effect as a single broadcast and incorporated application. We tested this hypothesis in a number of experiments aimed at assessing the effectiveness of seedrow placement of a variety of Cu products (sulphate, oxysulphate and chelated) at various rates (0 to 4 kg Cu ha-1) in the year of application, its residual effect after four annual applications and whether it can be combined with foliar Cu applications to provide an agronomic and economic solution both in the short and longer terms. Annual seedrow applications of up to 4 kg ha-1 were both agronomically and economically inferior to broadcasting and incorporation of 4 kg ha-1 as Cu sulphate; the former provided a statistically significant grain yield increase only in 3 of 10 site-years and only when the Cu fertilizer was in sulphate or chelated forms. However, yield increases thus obtained were neither economical nor as good as those obtained with broadcast and incorporated copper sulphate. The residual effects of seedrow-applied Cu at rates up to 4 kg ha-1 were very small compared to a single, 4-yr old broadcasting and incorporation of 4 kg Cu ha-1, and were obtained primarily after 3 yr of annual applications and with sulphate or chelated products only. However, average yield increases as a result of residual effects in the fifth year were approximately 35% of those obtained with broadcasting and incorporation. Combining seedrow with foliar applications did not have any agronomic or economic advantage, since most benefit arose from the latter. Key words: Broadcast and incorporation, sulphate, oxysulphate, chelate, residual

Description: The major horizons of Gleysolic and Chernozemic soils and the underlying deep till of five cores were separated into sand-, silt- and clay-sized fractions. Pedogenesis increased the ranges of magnetic susceptibility (χ) and oxalate (Feo) and dithionite-citrate extractable (Fed) iron in bulk samples and size separates of the A, B and IC horizons compared to the deep till. In the A, B and IC horizons the relationships between χ of the bulk (〈 2 mm diameter) soil and χ of the sand and silt fractions was much stronger than in the deep till. Generally, χ of the clay was much lower than that of the coarser fractions, whose χ was similar or slightly larger than that of the bulk samples, except for two buried, burned horizons. Treatment of the sand fraction of 15 soils with dithionite -citrate to remove pedogenic ferrimagnetics showed that the latter decreased in the order: burned, buried horizons 〉 gleysolic and chernozemic A horizons 〉 gleysolic B horizons 〉 IC horizons. The low χ of the gleysolic horizons cannot be attributed to a decrease in pedogenetically formed ferrimagnetics; they must have lost part of their inherited ferrimagnetics, possibly sand-sized magnetite. Key words: Magnetic susceptibility, soil separates, extractable iron, gleysols, chernozems

Description: Measurement of soil CO2 flux is an important tool for detecting management induced changes in soil C. The objective of this study was to analyze sources of variability of a recently published CO2 flux dataset to identify a sampling protocol with optimal allocation of replication, sub-sample and treatment numbers for detecting treatment differences. The dataset comprised daily CO2 flux measurements from a long-term study with treatments of conventional tillage (CT) and no-till (NT) under continuous wheat (CONT) and fallow-wheat rotation (F-W) in a randomized complete block design (RCBD) with four blocks. PROC MIXED in SAS was used to estimate variances. The standard error of the difference (SED) between two treatment means was used as the precision indicator. Although increasing the number of replications effectively reduced SED, sub-sampling also often improved detection of treatment differences because sub-sample variance (σ2δ) was higher than experimental unit variance (σ2ε) on most sampling days. When treatments with small CT vs. NT difference were excluded, degrees of freedom for treatment effects were reduced and both variances were generally increased or unchanged, resulting in increased requirement for sub-sampling. Based on the selected dataset, we produced graphs showing the number of days on which a CT vs. NT difference of 0.3 µmol CO2 m-2 s-1 could be detected at P 〈 0.10 as a function of replication, sub-sample and treatment numbers. This approach may be used as a guide to optimize sample allocation in similar studies, though site- and experiment-specific factors (e.g., spatial and temporal variability of CO2 flux, size of treatment difference to be detected, the required confidence level) should also be considered. Key words: Carbon dioxide emissions, tillage, variance, wheat

Description: A study of samples from a broad range of soils across the province of Saskatchewan, Canada, in 1999 has shown evidence that residues of organochlorine pesticides, and in particular DDT [1,1,1-trichloro-2,2- bis(4-chlorophenyl)ethane] and related compounds, are present even after several decades since the last application. In particular, residue levels of total DDT {DDTt = DDT + DDD [1,1-dichloro-2,2- bis(p-chlorophenyl)ethane] + DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene]} in Prince Albert National Park approach some of the highest levels measured to date at non-agricultural locations with concentrations of 119 to 150 ng g-1. Ratios of DDT:DDD:DDE were relatively consistent even from sites separated by several hundred kilometers and seem to be independent of soil properties and sample moisture levels over the region of study. These DDT:DDD:DDE ratios ranged from 9:1:4 for the Prince Albert Park site to 5:1:2 for Agriculture and Agri-Food Canada (AAFC) Research Centres and privately owned agricultural land. Data collected from AAFC Research Centres showed somewhat elevated levels of lindane [γ-1,2,3,4,5,6-hexachlorocyclohexane] (maximum 14 ng g-1), dieldrin [(1R,4S,4aS,5R,6R,7S,8S,8aR)-1,2,3,4,10,10-hexachloro-=6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro- endo-1,4,-exo-5,8-dimethanonaphthalene] (maximum 27 ng g-1) and chlordane [1,2,4,5,6,7,8,8-octachloro-2,3,3a,4,7,7a-hexahydro-4,7-methanoindene] (maximum 10 ng g-1), while samples collected from sites designated as “background” locations demonstrated a minimal effect from long-range atmospheric transport of organochlorines. Key words: Organochlorine residues, soil, Canada, decomposition products, pesticides

Description: Maintenance of soil quality and crop productivity is a major concern under intensive potato (Solanum tuberosum L.) production. The effects of four consecutive annual applications of 0.00, 2.25, 4.50 and 9.00 t ha-1 wet hay on growing season soil moisture and thermal regimes, soil quality and yield were evaluated on a loamy Orthic Humo-Ferric Podzol between 1995 and 1999. Hay mulching increased soil moisture at the beginning of the growing season by 6.5 to 12.7%, with increases significant until June 24, September 07 and September 20 for the 2.25, 4.50 and 9.00 t ha-1 treatments, respectively. Growing season soil temperature of the 4.50 and 9.00 t ha-1 treatments were lower than control, but only by −0.2 and −0.8°C, respectively. Hay mulching increased soil organic carbon (SOC) of the plow layer (0–25 cm), which increased biological activity resulting in better soil aggregation with more macropores, faster saturated hydraulic conductivity and reduced bulk density. Soil air CO2 concentration was significantly correlated to SOC content, aggregation, porosity and saturated hydraulic conductivity. Hay mulching at 2.25 and 4.50 t ha-1 increased total potato yield over that of the unmulched control by 11–14%, but was insufficient to maintain soil productivity. Hay mulching at 9.00 t ha-1 may have been excessive in terms of crop yield as it showed no total yield benefits. Key words: Organic carbon, CO2 concentration, aggregates, porosity

Description: Forest disturbances that increase P export from hillslopes will have negative consequences for site productivity and regional water quality. We studied P behavior in Gray Luvisols to understand the soil profile’s influence on P export from typical hillslopes of the Boreal Plain ecozone. We hypothesized that (1) P concentration is highest in upper horizons, (2) solution P is primarily in the dissolved and organic form, and (3) forest harvest will increase solution P concentration. We analyzed the soil solution, with emphasis on P, and determined P sorption properties of key soil horizons. Mean soluble reactive phosphorus concentration decreased with depth, ranging from 64 mg L-1 in the forest floor to 0.01 mg L-1 in the groundwater zone; solution P was mostly orthophosphate. Water soluble phosphorus decreased from 74 ± 9 to 41 ± 9 mg L-1 and extractable phosphorus was reduced in the forest floor only on two of four sampling occasions after harvest. Dissolved organic carbon may indirectly promote orthophosphate dominance in solution by complexing metal cations that would otherwise precipitate metal-P from solution. Gray Luvisols probably export P to soils lower on the hillslope catena, such as those of the Gleysolic and Organic Orders, both commonly associated with wetlands. Key words: Forest soil, phosphorus, orthophosphate, Gray Luvisol, biogeochemistry, sorption

Description: One of the prerequisites to phytoremediation of hydrocarbon-contaminated soils is that plants be able to germinate and become established in the presence of contaminants. This 5-wk growth chamber study examined the tolerance of five grasses and one legume to petroleum hydrocarbons (PHCs) and associated salts in three weathered, fine-textured, flare pit soils obtained from NE British Columbia. Plant tolerance to these soils was measured by percent seedling emergence (PSE), percent seedling survival (PSS) and 5-wk dry shoot biomass; a non-contaminated control soil was included in the study. The contaminated soils showed a wide range in total PHC concentrations (Soil A: 0.1 %, Soil B: 1.8 %, Soil C: 16 % PHC by mass) and in the recently established Canadian Council of Ministers of the Environment (CCME) PHC Tier 1 fractions 1–4. Electrical conductivity in contaminated soils ranged from 3.00 (Soil B) to 5.16 (Soil A) dS m-1. Medicago sativa (alfalfa, cv. Peace) was sensitive (low PSS, PSE and shoot biomass) to high salinity of Soil A but flourished in Soil B, a soil with F3 a nd F4 (gravimetric) concentrations that exceeded CCME PHC Tier 1 Eco Contact standards for agricultural, residential and parkland soils. When considering the combined effects of PHC and salts, Bromus inermis (smooth brome, cv. Carlton) was the grass most tolerant of contaminants in the weathered industrial soils. Compared to other plants, it consistently produced relatively high PSS, PSE and shoot biomass. Soil C was slightly hydrophobic and all plants showed reduced shoot biomass compared to other soils; however, average shoot biomass for Bromus inermis was almost twice as great as any other plant species growing in this soil. More research on the properties and remediation of historic flare pit soils is warranted. Key words: Hydrocarbons, phytoremediation, soil contamination, soil remediation, CCME, soil toxicity

Description: The spatial distribution of cesium-137 was examined at two uncultivated sites in the Black soil zone of Saskatchewan. Although considerable variability occurred at both sites, the variability was not systematically related to landscape position. Between 9 and 16 samples need to be taken from uncultivated grassland sites to reliably estimate the mean 137Cs concentration at such sites. Key words: Cesium, soil redistribution, landscape

Description: The distribution and dynamics of N following green manuring of full bloom field pea (Pisum sativum ’Sirius’) were investigated in the soil mineral, microbial and non-microbial organic (NMO N) fractions at two contrasting field sites in central Alberta; one on a Chernozemic (Dark Brown) soil near Provost and the other on a Luvisolic (Gray Luvisol) soil near Rimbey. Soils were sampled four times during a 1-yr period. The accumulations of N in the whole soil and in the soil mineral and microbial fractions were similar between sites. Net mineralization rates under controlled environments were strongly influenced by pre-incubation soil conditions. The short-term dynamics of N were distinguished best between the two soils by mineralization rates normalized to selected soil fractions rather than on the basis of N accumulation in these fractions. Net N mineralization rates expressed on the basis of soil N, microbial N or NMO N were greater in the Luvisolic soil indicating a more rapid internal N cycling system and greater activity of microbial biomass. These observations were consistent with the hypothesis that higher rates are associated with soils of lower clay content. Key words: Soil N dynamics, N mineralization rate, legume green manuring, Chernozemic, Luvisolic

Description: Studies were conducted to determine whether KCl application alone or in combination with Mn fertilizer would increase the bioavailability of indigenous and applied Mn and to study the mechanisms by which KCl could enhance Mn uptake by crops. The effect of rates of application (0, 50, 100 and 300 μg K g−1) of two KCl carriers (fertilizer grade and reagent grade KCl), as well as the effects of various salts (KCl, MnSO4, K2SO4, K2CO3, KCl + MnSO4, and KCl + MnSO4 + KI) on Mn uptake by wheat were examined. The effect of KCl on the solubility of soil Mn and applied Mn and the effect of K2SO4 on solubility of soil Mn were examined in calcareous and noncalcareous soils.The two KCl carriers behaved similarly in affecting Mn uptake by wheat. On the calcareous soil only the highest rate of KCl significantly enhanced Mn uptake, whereas on the slightly acidic soil both 100 and 300 μg K g−1 treatments significantly increased Mn uptake. Different salts differed significantly in affecting Mn uptake by wheat, and their effect was observed in the order KCl 〉 K2SO4 〉 〉 K2CO3 in both soils, with Mn uptake with K2CO3 being less than in the control. Application of KCl alone, at the higher rates, was as effective as MnSO4 alone in increasing Mn uptake by wheat. Mn uptake by wheat with dual application of MnSO4 and KCl was greater than with separate applications of MnSO4 or KCl. Addition of KCl to MnSO4 fertilizer bands increased amounts of water-soluble Mn in the fertilizer bands. K2SO4 was almost as effective as KCl in increasing water-soluble Mn in MnSO4 fertilizer bands but only for short periods of time (1–3 d). In contrast, KCl increased Mn solubility in the MnSO4 bands for periods up to 56 d. Key words: KCl fertilizer, KCl-enhanced Mn uptake, Mn availability, Mn solubility

Description: Distribution of NO3, P, K, Cl, pH and conductance through the soil profile were measured on two soil types after 4 yr of crop production using zero tillage (ZT) or conventional tillage (CT), with or without addition of KCl. All plots received N and P fertilizer each year as banded applications. Surface concentrations of NO3-N were higher under ZT than CT, particularly on the fine sandy loam soil. Accumulation of NO3-N also occurred in the 60- to 120-cm zone, under both tillage systems in both soils. Carryover of NO3-N was substantially greater on the silty clay than the fine sandy loam soil. Phosphate accumulated at the depth of band application in both soils under both tillage systems. Potassium concentration was generally higher under ZT than CT in the surface 15 cm of both soils, presumably due to surface retention of K from fertilizer applications and crop residues. Chloride was higher under ZT than CT in the surface 5 cm of both soils, but was higher under CT than ZT in the 30- to 60-cm and 60- to 120-cm depths in the silty clay soil, if KCl had been applied. The pH on both soils under both tillage systems was reduced in the 10- to 12.5-cm soil depth, corresponding to the zone of fertilizer application. On the silty clay soil, pH was higher under ZT than CT in the 10- to 15-cm depth and tended to be higher under ZT than CT at all depths below 15 cm. Conductance was not influenced by tillage in either soil. Application of KCl increased K and Cl concentrations in the surface 15 cm on both soils. Concentration of Cl was increased to 120 cm in both soils, indicating the mobility and leaching potential of this anion. Conductance and pH were increased in the 2.5- to 5.0-cm and 10- to 12.5-cm depths by KCl application in the fine sandy loam soil, but on the silty clay soil, only conductance was increased. Key words: Zero tillage, nutrient stratification, pH stratification

Description: Winter wheat, Triticum aestivum, is a new crop in south coastal British Columbia. The purposes of this study were to characterize plant development, dry matter accumulation and N uptake under low input and intensively managed systems as well as to assess the capability of some of the region’s soils to supply N to the crop. Grain yields, crop development and dry matter and N accumulation were similar to those reported from southern England. High amounts of winter rainfall (November–April precipitation ranged from 523 to 1111 mm) leach virtually all residual NO3 from south coastal B.C. soils and, without N fertilization, result in uniformly N deficient winter wheat. The low input N regime, 75 kg N ha−1 at Zadoks growth stage 31, plus soil N mineralized subsequent to the winter leaching period were sufficient in this study to maximize grain and total aboveground crop dry matter yields, but not to achieve adequate grain protein contents. The soils in the study were capable of supplying N in amounts sufficient to support only 30–53% of the maximum N uptake between growth stages 31 and 78. Appropriate quantities and timing of N are critical to successful production of high-yielding, good-quality wheat in south coastal British Columbia. Nitrogen management is likely to be most efficient when guided by the stage of crop development and demand and not by spring soil sampling and mineral N analysis. Key words: Winter wheat, N demand, soil N supply, crop development, intensive crop management, low input

Description: Cost-effective methods to map differences in productivity across fields have potential application for site-specific management of fertilizer and pesticides. In this study, zones were delineated for a field with hummocky topography in southwestern Saskatchewan by clustering the normalized difference vegetation index (NDVI) derived from Landsat TM information. Zones uniqueness were confirmed if zones differed in grain yield. Two different zones were delineated in the field. These zones had significant (P 〈 0.05) differences in soil factors related to productivity: average solum depth, spring soil nitrogen (N), phosphorus (P), and spring soil moisture. Over 4 yr, the two zones also had different spring wheat (Triticum aestivum L.) grain yield and protein content. The yield response to N-P fertilizer blend within each zone was different with no significant response to N-P fertilizer in the zone with higher NDVI values versus a significant response to N-P in the zone with lower NDVI. The results indicate a potential economic advantage to reducing fertilizer application to the zone without fertilizer response. Further, the residual soil NO3-N in the zone without fertilizer response was positively correlated with N application in the previous year. Therefore, there is a potential environmental benefit to reducing fertilizer application to that zone to decrease residual NO3-N, which can leach and contaminate ground water or can be denitrified to the greenhouse gas, N2O. Hence, this relatively simple and low-cost method of zone delineation has potential practical application to realize economic and environmental benefits from site-specific management of fertilizer.

Description: We investigated the nature of the layer charge of the different expandable 2:1 phyllosilicates present in glacial till, marine sediment, beach sand, loess, weathered sandstone and acid shale parent materials of selected soils from the arctic, alpine and interior plateau regions of Canada. Detailed characterization of 2:1 clay minerals, using the layer charge, was done by intercalation of the clay fractions with different chains (nc = 6 to 18) of n-alkylammonium cations (AC).Results indicated that AC were able to detect a mixture of smectite and vermiculite that was not detected by previous studies, using the glycerol (GLY) and ethylene glycol (EG) solvation techniques. The mean unit cell layer charge [in mol(+)/Si,Al)4O10)] varies from 0.30 to 0.39 for the smectite and from 0.71 to 0.74 for vermiculite. Vermiculite from the beach sand is trioctahedral in which most of the charge is located in the tetrahedral sheet, while vermiculite in the weathered sandstone is dioctahedral in which part of the charge originates from the octahedral layers. The presence of smectite, associated with the weathering of chlorite and an expanding component associated with the degradation of biotite, was also observed. Key words:n-alkylammonium cations, mean layer charge, 2:1 phyllosilicates

Description: The field persistence of trifluralin from fall treatments of both emulsifiable concentrate (EC) and granular formulations was investigated at two sites in Saskatchewan over a 2-yr period. At both locations, there were no significant differences (P = 0.05) in trifluralin persistence from fall applications of either formulation. In addition, the carryover of trifluralin residues in farmers’ fields following fall and spring applications of EC and granular formulations was monitored at several Saskatchewan locations to determine their persistence under typical farming practices. Trifluralin residue data indicated that following fall applications, the percent carry-over to the first spring was 83 ± 21(15 fields sampled) and 37 ± 15 (28 fields sampled) to the second spring; and that following spring applications, the percent carry-over to the next spring was 33 ± 12 (14 fields sampled). Key words: Field studies, persistence, formulations, trifluralin, herbicide

Description: Soil survey is a paradigm-based science that relies heavily on the application of conceptual soil-landscape models, which in turn are based upon tacit pedological knowledge. This tacit knowledge is generally acquired by systematic field observation and recording the relationships between the occurrence of soils and associated landform positions. Soil survey databases identify the types of soils within a delineated area but they do not generally describe the relationship of specific soils with specific landscape positions. A case in point is the recently completed 1:100 000 scale soil landscape database prepared for the agricultural region of Alberta, Canada. In order to utilize this database with various interpretative algorithms a procedure for allocating soils to specific landform positions needed to be developed. The development of this procedure initially involved capturing the local tacit pedological knowledge in a series of tables and programs. The procedure was then applied to the Alberta soil survey database to automatically assign soils to landform positions and then to assign specific slope characteristics to the individual soils. The resulting soil-landform product was more useable than the original data for input to land based process models. Key words: Soil survey, tacit knowledge, soil-landscape modeling, heuristic rule base, predictive mapping

Description: The Mn release by M KCl from two Oxisols from Indonesia and one Inceptisol from Oregon, USA was studied at different temperatures (25, 35 and 45 °C) to understand the kinetics and mechanism of Mn release from these soils, which were reported to have a Mn toxicity problem. The Mn release by M KCl continued to increase with time up to at least 772 h without reaching equilibrium. The kinetics of Mn release followed a parabolic diffusion model during the 0.25–772 h reaction period. The activation energy of Mn release, calculated from the overall diffusion coefficients, varied from 34 to 47 kJ mol−1. Even after removing the exchangeable Mn from the soils with M calcium nitrate, significant amounts of Mn were released by M KCl. Data presented indicate that ionic strength effect coupled with Cl complexation was the main mechanism governing the KCl-induced Mn release. The Mn release from the soils during the initial reaction period (0.25 h) was fast and accounted for 34–39% of the total amount of Mn released during the 772 h reaction period. The significantly high Mn release during the initial 0.25 h reaction time, the high overall diffusion coefficients of Mn release, and the high values of the pre-exponential factor (calculated from the Arrhenius equation) of Mn release from Mn-toxic soils apparently contributed to the KCl-induced Mn toxicity in these soils. Key words: Potassium chloride-induced Mn toxicity, pre-exponential factor, ionic strength, complexation

Description: Mineral composition of the parent material is a major factor controlling natural radioactivity of soils. The objective of this study was to investigate the relationship between the natural radioactivity of 18 till and six lacustrine parent materials and their properties measured during soil surveys. Gamma spectroscopy was used to estimate 40K and daughters of 238U and 232Th; neutron activation analysis was used to determine total U; and alpha counting was used to measure 222Rn release from the soil. The amounts of the various radioisotopes were positively correlated with each other and with clay content; the correlation with sand content was negative; and the correlations with silt and inorganic C content were generally not significant. Adding the fine/total clay ratio as a further independent variable considerably improved the correlation between 40K and clay content. The data suggested considerable disequilibrium in the 238U decay chain, which appeared to be in part related to the mode of deposition of the parent materials. Soil survey information — in particular, texture — thus appears a readily available tool for preliminary screening of terrestrial radiation in Saskatchewan. Key words: Radioactivity, 40K, uranium, thorium, radon, texture

Description: Barley receiving unlabelled nitrogen fertilizer was grown among treatments receiving Ca(15NO3)2 fertilizer (5 atom %) in a growth cabinet with high air exchange and in a greenhouse. In both environments, the unlabelled plants and soil were significantly enriched with 15N, apparently, in part, by foliar exchange of atmospheric ammonia. This exchange may warrant consideration in the selection of appropriate controls for 15N calculations. Key words:15N, ammonia, atmospheric exchange

Description: Palaeosols, formed prior to deposition of Mazama tephra (6600 yr B.P.), are widespread in Alberta. Palaeo-Ahb horizons are readily identifiable, with colors ranging from very dark gray to gray and brown. Establishment of fundamental and stable properties of the original organic matter would facilitate the classification of these buried soils. Use of a suite of eight monosaccharides divided the 15 palaeosols examined in this study into one group of three, possibly formed under Brown Chernozemic soil-forming conditions or drier, and the remainder, possibly formed under Black Chernozemic soil-forming conditions. The former had C/N ratios approaching those of microorganisms and low xylose to mannose ratios. It is concluded that, because of the long time-window of surface stability between deglaciation and the Mazama tephra fall, pre-Mazama palaeosols can only be studied on a site-specific basis. Grouping these palaeosols, based on their pre-Mazama tephra deposition only, is not realistic. Synthesis of a unified hypothesis of palaeoenvironmental conditions is, therefore, not possible using only their monosaccharide status. Key words: Holocene soils, palaeosols, buried soils, monosaccharides, landscape

Description: In order to assess to what extent soil nutrient properties support differentiation of field-identified soil nutrient regimes, composite samples from each forest floor and 0–30 cm of the mineral soil were collected from 116 forest stands in central British Columbia. The samples were analyzed for acidity, total carbon (tC), total nitrogen (tN), mineralizable-N (min-N), and extractable Ca, Mg, K, P, and SO4-S (eCa, eMg, eK, eP, eSO4); and the results were expressed as concentrations on a dry-mass basis. Mineralizable-N of the mineral soil showed (1) the largest amount of variation in the population of sampled soils, (2) significant differences (P 

Description: Kochia scoparia (L.) Schrad. naturally invades mechanically disturbed soils in the Brown and Dark Brown soil zones of the Canadian Prairies and offers potential as a forage crop in saline environments. A 3-yr study conducted on severely saline soil (~ 11 dS m−1) near Swift Current, Saskatchewan, evaluated the production of kochia forage and plant-N uptake following applications of 0, 56, 112 and 168 kg N ha−1 of ammonium nitrate. The yield response in aboveground, dried forage (Y) followed a curvilinear function based on the quantity of nitrogen applied (N): Y = 4740 + 38.5N − 0.121N2. The N-fertilizer requirement to produce 7500 kg ha−1 of dried forage (96% of the function maximum) equalled 110 kg N ha−1 and reflected average growing conditions at the study site during 1987–89. The kochia assimilated protein N (Kjeldahl) within its tissue in direct proportion to the fertilizer dosage applied, reaching theoretical maxima which varied yearly: 18 g kg−1 in 1987, 12 g kg−1 in 1988 and 22 g kg−1 in 1989. Although NO3-N concentrations increased with each addition of fertilizer N, the maximum accumulation of NO3 N (0.5 g kg−1) among all the tests and treatments was within the safe limit of 1.1 g kg−1 to avoid livestock poisoning. The efficiency with which the fertilizer N was assimilated by the kochia ranged between 44 and 69% over the test years and fertilizer treatments. Key words: Saline soil, N fertilization, kochia forage, soil fertility, salinity

Description: The hypothesis that phospholipid-linked fatty acid methyl ester (PL-FAME) analysis of a soil characterizes lipids from within microbial cells (cellular) as distinct from lipids stabilized in soil organic matter (extracellular) was tested by measuring the sensitivity of PL-FAME analysis to numbers of bacteria in samples of a soil. Autoclaved samples from the Ap horizon of a soil having a sandy loam texture were inoculated with suspensions of a Pseudomonas sp. (day 0) to form bacterial microcosms. On day 2, half of the microcosms were inoculated with an Acanthamoeba sp., a protozoan that grazes on pseudomonads.The numbers of bacteria in the soil samples without or with Acanthamoeba sp. increased about five-fold between days 2 and 4. Between days 4 and 7, the numbers of pseudomonads in grazed microcosms decreased 10-fold and the numbers of Acanthamoeba sp. increased 10-fold, relative to those in nongrazed microcosms. The 10-fold relative difference in numbers of pseudomonads between nongrazed and grazed samples persisted through day 12. Cluster analysis grouped PL-FAME profiles from grazed with those from nongrazed microcosms on day 4. On days 7 and 12, PL-FAME profiles from grazed or nongrazed microcosms clustered separately. The PL-FAME profiles from sterile samples of soil on days 2, 4, 7, and 12 clustered with profiles on day 2 from microcosms inoculated with Pseudomonas sp.We infer that PL-FAME analysis is selective for cellular lipids in the sandy loam soil with the limited range of active organisms used here. Further extension of PL-FAME analysis to a wider range of soils and soil conditions is warranted. Key words: Phospholipid-linked fatty acid, PL-FAME, soil lipids, Pseudomonas, Acanthamoeba

Description: Relationships between cation exchange capacity (CEC), clay and organic carbon contents and soil pH were analyzed by way of multiple regressions for upland soils in eastern Canada (mostly Ontario, with additional data for New Brunswick). This was done by vegetation type in an attempt to explain some of the otherwise unexplained CEC variations. Data were taken from about 2000 soil horizons (organic L, F, and H horizons as well as A, B, and C mineral soil horizons) under broadleaves (mostly maples, beech, birch or aspen as dominant species), conifers (mostly fir, spruces and/or pines), and grass vegetation. For the organic forest floor horizons (or L, F, and H horizons), both organic carbon content (%) and pH were highly significant for predicting CEC, i.e.,CEC (L, F, and H of broadleaves) = −38 + 0.71 × org. C (%) + 10.3 × pH (R2 = 0.69), andCEC (L, F and H of conifers) = −31 + 0.34 × org. C (%) + 12.1 × pH (R2 = 0.58).For the mineral soil, clay and organic carbon contents (%) and pH were highly significant for predicting CEC. Soils with forest vegetation were found to have lower contributions of organic matter to CEC than grassland soils, i.e.,CEC (forest soils) = −7.0 + 0.29 × clay (%) + 0.82 × org. C (%) + 1.4 × pH (R2 = 0.72),CEC (wooded grasslands) = −6.0 + 0.31 × clay (%) + 1.31 × org. C (%) + 1.0 pH (R2 = 0.74), andCEC (grasslands) = −8.3 + 0.24 × clay (%) + 2.14 × org. C (%) + 1.3 × pH (R2 = 0.79).Relationships that were developed from Ontario data for specific vegetational types (maple sites, strongly podzolized conifer sites, grasslands/croplands) were tested by comparing CEC predictions with reported values for similar sites in New Brunswick and Quebec. The predictions were consistent with the general trends for maple sites and grasslands/croplands, but CEC values were strongly overpredicted for Podzolic subsoils on conifer sites.Literature information of the CEC dependency on in situ pH is sparse. Existing information that is based on buffering grassland/cropland soil samples from pH 2.5 to 8 appears to mimic this dependency quite well. Key words: Cation exchange capacity, clay, organic carbon, soil pH, forests, grasslands