Liu, K., Hammermeister, A. M., Warman, P. R., Drury, C. F. and Martin, R. C. 2011. Assessing soil nitrogen availability in contrasting cropping systems at the end of transition to organic production. Can. J. Soil Sci. 91: 493-501. Quantifying soil nitrogen (N) availability at the end of a transition period for converting conventional fields to organic fields could enhance N management during the subsequent organic crop production phase. Soil total N (N_tot), KCl extractable N (KCl N) and potentially mineralizable N (N_o) were determined at the end of a 3-yr transition period. A complementary greenhouse ryegrass N bioassay was conducted using soils collected from the treated field plots. The field experiment consisted of six cropping systems comprising two N inputs (legume-based vs. manure-based) and three forage cropping treatments (0, 1 or 2 yr of forage in 4-yr rotations). The N input treatments consisted of alfalfa meal in the legume-based cropping system (LBCS) and composted beef manure in the manure-based cropping system (MBCS). Orthogonal contrasts suggested no differences in N_tot or KCl N either between LBCS and MBCS or between no-forage and forage cropping systems. However, in the greenhouse study, high cumulative N inputs in the MBCS resulted in significantly higher ryegrass N uptake and potentially mineralizable soil N than in the LBCS. Ryegrass N uptake ranged from 101 to 139 kg ha^-1, which should be an adequate N supply for the succeeding potato crop. In the greenhouse, a ryegrass N bioassay effectively identified the differences in soil N availability. Ryegrass N uptake was linearly related to cumulative soil amendment N inputs but had no apparent relationship with N_o. A systems approach provided a good assessment of N availability at the end of the transition period to organic production.

Kröbel, R., Smith, W. N., Grant, B. B., Desjardins, R. L., Campbell, C. A., Tremblay, N., Li, C. S., Zentner, R. P. and McConkey, B. G. 2011. Development and evaluation of a new Canadian spring wheat sub-model for DNDC. Can. J. Soil Sci. 91: 503-520. In this paper, the ability of the DNDC model (version 93) to predict biomass production, grain yield and plant nitrogen content was assessed using data from experiments at Swift Current, Saskatchewan, and St-Blaise, Quebec, Canada. While predicting wheat grain yields reasonably well, the model overestimated the growth of above-ground plant biomass and nitrogen uptake during the first half of the growing season. A new spring wheat sub-model (DNDC-CSW) was introduced with a modified plant biomass growth curve, dynamic plant C/N ratios and modified plant biomass fractioning curves. DNDC-CSW performed considerably better in simulating plant biomass [modeling efficiency (EF): 0.75, average relative error (ARE): 6.0%] and plant nitrogen content (EF: 0.61, ARE: -2.7%) at Swift Current and St-Blaise (EF of 0.75 and ARE of 2.3%), compared with DNDC 93 (biomass SC: EF 0.49, ARE 17.1%, SB: EF 0.02 ARE 33.4%). In comparison with DNDC 93, DNDC-CSW better captured inter-annual variations in crop growth for a range of wheat rotations, increasing the EF from 0.32 to 0.52 for grain and from 0.35 to 0.39 for straw yields. DNDC-CSW also performed considerably better than DNDC 93 in estimating soil carbon changes at Swift Current. Hence, DNDC-CSW has the potential to improve the performance of DNDC 93 in simulating wheat biomass, plant nitrogen, yield and soil carbon at various Canadian sites.

Li, X., Ziadi, N., Bélanger, G., Cai, Z. and Xu, H. 2011. Cadmium accumulation in wheat grain as affected by mineral N fertilizer and soil characteristics. Can. J. Soil Sci. 91: 521-531. Cadmium (Cd) is a heavy metal distributed in soil by natural processes and anthropogenic activities. It can accumulate in crops, such as spring milling wheat (Triticum aestivum L.), and its accumulation depends on crop species, soil factors, and agricultural practices like fertilizer inputs. Our objective was to study the effect of mineral N fertilizer and soil characteristics on wheat grain Cd concentration. A field study was conducted over 12 site-years (2004-2006) in Québec, with four N application rates (0, 40, 120, and 200 kg N ha^-1). Wheat grain samples (n=192) were analysed for their Cd and N concentrations. Soil samples (n=48) taken before N fertilizer application were characterised for their chemical and physical properties, including Mehlich-3 extractable Cd concentration. Wheat grain Cd concentration increased significantly with increasing N application rates at 11 of the 12 site-years. Averaged across the 12 site-years, Cd concentration ranged from 53 µg kg^-1 dry matter (DM) without N applied up to 87 µg kg^-1 DM when 200 kg N ha^-1 was applied. Wheat grain Cd concentration also varied significantly with site-years (34-99 µg kg^-1 DM), but never exceeded the proposed tolerance for wheat grain of 235 µg kg^-1 DM. Wheat grain Cd concentration was significantly related to Mehlich-3 extractable Cd in soil (R²=0.44, P=0.021) and nitrogen nutrition index (R²=0.69, P=0.001). We conclude that soil Cd concentration and the crop N nutrition status affect Cd accumulation in spring wheat grain produced in eastern Canada.

Moulin, A. P., Buckley, K. E. and Volkmar, K. 2011. Soil quality as affected by amendments in pinto bean-potato rotations. Can. J. Soil Sci. 91: 533-542. The potential for adverse effects on soil quality and erosion in pinto bean-potato rotations is significant due to low levels of residue input to the soil following potatoes or beans, and the effect of tillage on soil structure, particularly in sandy-textured soils typical of the potato-growing area of Manitoba. Soil quality is reduced by low inputs of residue and carbon commensurate with an increase in the proportion of small and unstable aggregates susceptible to erosion. Furthermore N and P concentrations at the soil surface may be affected by various management options including fall cover crops, application of straw and the use of composted manure. In a study conducted at Carberry, MB, from 2000 to 2006, KCl-extractible NO₃-N and Olsen P were determined in the fall prior to seeding in each year of the study. Water-soluble P, determined in the fall of 2005 for selected treatments, increased with application of compost. Soil organic C, total N and the proportion of erodible (<0.5-mm diameter) aggregates and stability of aggregates were measured in 2006 for treatments with fall-applied compost, cereal straw, and spring-applied anionic polyacrylamide (PAM). The proportion of erodible aggregates and aggregate stability were not consistently affected by treatment. Application of PAM did not affect stability of wet-sieved aggregates (1.3 to 2.0 mm), but decreased the proportion of small aggregates (<0.5 mm) in 2002. Soil C in the 0- to 5-cm depth increment increased with fall application of composted beef cattle manure. However, no effect was observed on the dry-sieved distribution of aggregates <0.5 mm in diameter. Soil quality, as indicated by an increase in soil organic C, can be improved by application of composted beef cattle manure, but levels of water-soluble P will increase, potentially increasing the risk of high concentrations of P in runoff. This research shows that the addition of compost and straw improves soil quality in terms of soil carbon and aggregate stability in bean-potato rotations. However, the proportion of erodible aggregates also increased, though not to levels that contribute significantly to soil erosion. Compost inputs must be monitored to reduce the potential for high concentrations and runoff of water-soluble P at the soil surface.

Mir Mohammad Hosseini, S. M., Ganjian, N. and Pashang Pisheh, Y. 2011. Estimation of the water retention curve for unsaturated clay. Can. J. Soil Sci. 91: 543-549. Extensive laboratory tests are essential in order to determine the soil water retention curve, defined as the relationship between water content and suction, in an unsaturated soil. These laboratory tests are usually costly and time consuming. Moreover, for most practical problems, it has been found that approximate unsaturated soil properties are adequate for analysis. Thus, empirical procedures for predicting unsaturated soil parameters would be invaluable. The water retention curve can be estimated using soil properties to avoid the costs of experimental methods. Estimation of the water retention curve based on index properties is highly desirable due to its simplicity and low cost. Here, a model for the estimation of the soil water retention curve for fine soils is introduced, which takes the plasticity index and fine content into account, and is based on the Van Genuchten and Fredlund-Xing equations. The proposed equations are validated by comparing measured and simulated results. The curves predicted with these models were found to be in good agreement with the experimental results.

Ozturk, M., Salman, O. and Koc, M. 2011. Artificial neural network model for estimating the soil temperature. Can. J. Soil Sci. 91: 551-562. Although soil temperature is a critically important agricultural and environmental factor, it is typically monitored with low spatial resolution and, as a result, methods are required to estimate soil temperature at locations remote from monitoring stations. In this study, cost-effective, feed-forward artificial neural network (ANN) models are developed and tested for estimating soil temperature at 5-, 10-, 20-, 50- and 100-cm depths using standard geographical and meteorological data (i.e., altitude, latitude, longitude, month, year, monthly solar radiation, monthly sunshine duration and monthly mean air temperature). These data plus measured monthly mean soil temperature were collected for 2006-2008 from 66 monitoring stations distributed throughout Turkey to obtain a total of 2376 data records (36 months×66 monitoring stations) for each of the five soil depths. At each soil depth, 1800 randomly selected data records were used to develop and train a separate ANN model, and the remaining 576 records at each depth were used to test and validate the resulting models. Good agreement was obtained between ANN-estimated soil temperature and measured soil temperature, as evidenced by correlation coefficients of 98.91, 97.99, 99.03, 98.26 and 95.37% for the 5-, 10-, 20-, 50- and 100-cm soil depths, respectively. It was concluded that ANN modeling is a reliable method for predicting monthly mean soil temperature in regions of Turkey where soil temperature monitoring stations are not present.

Dampier, L., Sanborn, P., Smith, S., Bond, J. and Clague, J. J. 2011. Genesis of upland soils, Lewes Plateau, central Yukon. Part 1: soils formed on Pleistocene glacial deposits. Can. J. Soil Sci. 91: 563-578. We describe and interpret nine upland (>1000 m asl) Dystric Brunisols and one Humo-Ferric Podzol formed on till of the McConnell [Marine Isotope Stage (MIS) 2] and penultimate (MIS 4 or 6) glaciations on the Lewes Plateau of central Yukon Territory. Unlike soils formed on correlative glacial deposits at lower elevation in the nearby Tintina Trench, the soils on the Lewes Plateau display only weak age-related differences. Penultimate and McConnell soils have solum thicknesses of 50-75 cm and <50 cm, respectively, but other morphological and chemical properties do not differ between the two age groups. Smectite is present in the McConnell soils; it was previously reported only in soils formed on Early Pleistocene glacial deposits in central Yukon and was interpreted to reflect weathering and soil formation during warm interglaciations. Paleoclimatic interpretations of clay mineralogy in central Yukon may be confounded by differences in parent material provenance and should be reassessed. This study shows that field soil characteristics alone are insufficient to differentiate McConnell and penultimate glacial deposits in upland landscape positions on the Lewes Plateau.

Dampier, L., Sanborn, P., Smith, S., Bond, J. and Clague, J. J. 2011. Genesis of upland soils, Lewes Plateau, central Yukon. Part 2: Soils formed in weathered granitic bedrock. Can. J. Soil Sci. 91: 579-594. Polygenetic soils have formed on weathered granitic bedrock at high elevation (>1200 m asl) beyond the penultimate glacial limit on the Lewes Plateau in central Yukon Territory. Solum thickness in four Brunisols that were examined exceeds the depths of excavated pits (85-110 cm), but data indicate limited chemical weathering. Clay mineralogy is dominated by vermiculite and kaolinite. Smectite and chlorite are present in horizons derived, respectively, from residuum and colluvium. Sola are strongly cryoturbated, in spite of the lack of permafrost at these sites today. Three scenarios are proposed to explain these soils: preservation of relict soil features beneath cold-based ice, prolonged interglacial soil formation following erosion of till deposited by warm-based ice, and ice-free conditions throughout the Quaternary, with soil evolution shaped by multiple glacial-interglacial cycles.

Rees, H. W., Chow, T. L., Zebarth, B. J., Xing, Z., Toner, P., Lavoie, J. and Daigle, J.-L. 2011. Effects of supplemental poultry manure applications on soil erosion and runoff water quality from a loam soil under potato production in northwestern New Brunswick. Can. J. Soil Sci. 91: 595-613. Soil erosion is a major threat to the economic viability of potato production in northwestern New Brunswick. One option for growers to increase soil organic matter and improve soil quality in potato fields is through poultry manure application. While poultry manure may be beneficial for soil quality, there are also potential risks to surface water quality associated with manure application. This study evaluated the effects of time of poultry manure application on potato fields in northwestern New Brunswick on soil erosion and runoff water quality. Seven permanent Wischmeier-like erosion plots, established in 1982, were used. Treatments consisted of a control (Ctrl) with no manure applied, and applications of 4 Mg ha^-1 of fresh poultry broiler manure in late fall (F), pre-planting (PP) and pre-hilling (PH) on 11% slope plots and a Ctrl, F and PH treatments on 8% slope plots. All poultry manured treatments increased potato total yield with a general trend of Ctrl<F<PH<PP, but only the 8% PH increase was significant (P<0.10). Potato yield of fall-applied poultry manure did not result in a significant reduction in yield compared with other treatments. May to October runoff was significantly reduced on the 11% PH, but increased on the 8% F treatment. May to October soil loss was significantly reduced on the 11% PH and 11% PP. The soil loss:runoff ratio was reduced by up to 15% with PP and PP<PH<F<Ctrl. Fall applications generally resulted in the greatest mean annual flow-weighted nutrient runoff concentrations and runoff nutrient loadings whereas PH resulted in some of the lowest nutrient concentrations and loadings. While high background concentrations of Escherichia coli were found in runoff, E. coli concentrations in runoff were increased 20-230% by manure application. Escherichia coli colonies survived the winters in northwestern New Brunswick and populations were cyclical being highest in summer and lowest in winter. Escherichia coli concentrations in runoff were significantly (P<0.10) correlated with air and soil temperature and soil loss. The PH appeared to provide the best balance between crop production and surface water protection. Further replicated research is required to support these results.

Illés, G., Kovács, G. and Heil, B. 2011. Comparing and evaluating digital soil mapping methods in a Hungarian forest reserve. Can. J. Soil Sci. 91: 615-626. To investigate applications of widespread digital soil mapping methods in forestry management, soil maps for a Hungarian forest reserve were developed using general discriminant and classification tree analysis as predictive tools. Soil samples were collected applying an unaligned semi-systematic grid. Second level units of the World Reference Base of Soil Resources and their yield capacity were determined. Terrain attributes were derived using a digital elevation model, and they were assigned to soil data to be used as predictors for second level units of the World Reference Base for Soil Resources (SLU) maps. A comparison was made of prediction accuracy. Both the discriminant analysis and the classification tree-based prediction were able to derive SLU maps; however, the classification accuracies were uneven. The methods used provided 63-65% average classification accuracy for dominant SLUs, but only 0-18% in the case of less common SLUs. One of the major issues of digital soil mapping that needs to be addressed is that the same inputs may result in different output maps depending on the use of spatial predictions. To overcome this problem we created a new combination of these methods in which the classification accuracies were used to select the most appropriate prediction. For each location, the method that gave higher prediction accuracy was used to extend the soil map to unknown areas. In this way we improved the overall accuracy of output maps as well as the prediction accuracies of individual SLUs.

Moussadek, R., Mrabet, R., Zante, P., Lamachère, J. M., Pépin, Y., Le Bissonnais, Y., Ye, L., Verdoodt, A. and Van Ranst, E. 2011. Impact of tillage and residue management on the soil properties and water erosion of a Mediterranean Vertisol. Can. J. Soil Sci. 91: 627-635. Soil erosion research on Mediterranean Vertisols under no tillage systems (NT) is still scarce. A rainfall simulator was used on Vertisols to compare water runoff and soil loss in a conventional tillage system (CT), NT system with crop residues removed (NT0), and NT with 50% of crop residues returned to the soil surface (NT50). Runoff and soil loss rates were more than 50% lower under NT50 compared with NT0 and CT. Wet aggregate stability (MWD), soil organic matter (SOM) and soil bulk density (Da) were significantly higher under NT than under CT. A multiple regression analysis showed that when the soil was dry, Da explained 84 and 96% of the variation in water runoff and soil loss, respectively. Under wet soil conditions, MWD explained 47 and 69% of variation in water runoff and soil loss, respectively. Consequently, although NT systems improved soil quality (MWD, SOM) compared with the CT system, returning 50% of crop residues at the soil surface was mandatory under NT to protect these Vertisols against water erosion.

Tremblay, G. J., Boisvert, J., Fréchette, G. É., Saulnier, M., Alexandre, R. and Vanasse, A. 2011. Mid term evaluation of mineral fertilizer requirements (N, P, K) of a field crop rotation on a clay soil. Can. J. Soil Sci. 91: 637-646. In Quebec, the recommended fertilizer requirements have been lowered since 1994. A study was undertaken from 1998 to 2005 in a 4-yr rotation of wheat (Triticum aestivum L.), soybean [Glycine max (L.) Merr.] and grain corn (Zea mays L.) to verify the mid-term mineral fertilizer requirements (N, P, K) for these field crops. Four levels of nitrogen (N) and three levels of phosphorus (P) and potassium (K) were compared on a clay soil of the Saint-Lawrence Lowlands. Nitrogen requirements based on this study corresponded to the recommended levels of each field crop tested. Recommended phosphorus rates did not maintain initial P_M-III soil level (1998). However, crop yields were not affected by this decrease in soil P_M-III level. To improve fertilizer recommendation tables, it should be relevant to determine with more accuracy the critical phosphorus and potassium values for field crops on other typical Quebec soils.

Kowalenko, C. G. and Ihnat, M. 2011. Fraser oat and soil extraction responses to zinc and manganese applied to a soil with historic limestone treatments. Can. J. Soil Sci. 91: 647-659. A field trial initiated in 1979 examined the possibility of zinc (Zn) and manganese (Mn) deficiencies when limestone was applied to an acidic (approximately pH 5) soil at Agassiz, British Columbia. The results from an initial phase of the study conducted from 1979 through 1985 with cauliflower as the test crop and foliar Zn and Mn have been reported. This study reports on a follow-up to that study, with a focus on the effect of historic limestone treatments on oats with soil rather than foliar applications of Zn and Mn. Oats was selected for this phase, since it is widely assumed to be sensitive to low Mn contents, and was grown from 1988 through 1990. The limestone treatments were made in 1979, 1981 and 1986 at two rates (9 and 19 Mg ha^-1 each time). The micronutrient treatments were applied to the soil in each of the 3 yr of oat growth to plots that did not have previous soil micronutrient applications. Quantitative visual measurements showed that limestone applications reduced the vigor of common groundsel (Senecio vulgaris L.) weed when the plot area was being fallowed in 1987. In 1988, nitrogen (N) deficiencies were confirmed by visual observations and soil and plant measurements, especially in the treatment with no limestone applied. Adjustments were made to the amount of N fertilizer applied in 1989 and 1990 to eliminate the complication of N deficiencies to the assessment of the effects of limestone on potential Zn and Mn deficiencies. Visual assessment, and plant and soil measurements confirmed that adequate N had been applied. Visual symptoms, dry matter measurements and nutrient contents in the crop showed that Mn and, to a lesser extent, Zn deficiencies were induced by the historic applications of limestone. The effects were quite small showing that these micronutrients were only marginally deficient. Mehlich-3 solution tended to extract more calcium (Ca) and less Mn and Zn from limestone-treated soil than control soil, similar to the response of the crop, showing the potential of this soil test to predict limestone-induced Mn and Zn deficiencies. Although plant uptake and corresponding soil extractions of Ca, Zn and Mn were consistent with regard to treatment effects, the relationships were weak, but provide sufficient information for using soil measurements to assist designing better follow-up studies. Plant measurements showed unexpected increases of iron (Fe) uptake by the crop with increased limestone application rates, whereas, limestone had the opposite effect on soil extraction of the element. Further work is required to determine why this occurred.

Pinno, B. D. and Bélanger, N. 2011. Estimating trembling aspen productivity in the boreal transition ecoregion of Saskatchewan using site and soil variables. Can. J. Soil Sci. 91: 661-669. The productivity of trembling aspen, as expressed by site quality index (SQI), in natural stands growing on three different soil parent material types (fluvial, lacustrine and glacial till) in the boreal transition ecoregion of Saskatchewan was evaluated by using soil and site variables. The soil and site variables used were either general categorical variables, such as parent material and ecosite, or continuous variables, such as soil texture (percent sand or clay), pH, carbon, nitrogen, C:N ratios, and elemental composition. It was not possible to reliably estimate SQI using only categorical site variables or continuous soil variables when all plots were grouped together. However, when plots were grouped by parent material type, over 45% of the variability in trembling aspen productivity was explained using the common soil measurements of texture and pH. In estimating SQI, there was an interaction between both pH and soil texture with parent material. On fluvial and lacustrine parent materials, increased clay content was positively correlated with SQI, but was negatively correlated with SQI on till, while pH was positively correlated with SQI on fluvial parent material, but negatively on lacustrine. Including more sophisticated measures of soil nutrient availability in the forest floor and BC horizons did not improve the SQI prediction. This study indicates that it is possible to estimate trembling aspen productivity using simple site and soil variables, provided that differences in soil properties within parent material groupings are considered in the analysis.