Cohen-Fernández, A. C., Naeth, M. A. and Wilkinson, S. R. 2013. Anthroposol development from limestone quarry substrates. Can. J. Soil Sci. 93: 555-566. Limestone quarry reclamation worldwide requires development of substrates or anthroposolic soils. The suitability of three limestone substrates (gray, gray brown, crushed) for revegetation was assessed in two greenhouse experiments. In the first experiment amended substrates (pulp mill sludge, two manures, hay, straw, wood shavings, capping with two soils) alone and in combination with fertilizer and elemental sulfur were evaluated. Amendment rates were assessed in a second experiment. Plant density and above- and below-ground biomass were used to determine substrate suitability. The three limestone substrates supported germination, emergence and establishment of five native grasses when amended. Addition of fertilizer yielded three times more above-ground biomass and two times more below-ground biomass compared with the control, despite reducing plant density. Sulfur application did not significantly affect plant variables. Capped topsoil, clean fill and incorporated pulp mill sludge yielded the highest above-and below-ground biomass and plant density. To a lesser extent manure compost favorably changed plant parameters, but hay and straw did not. High fertilizer and amendment rates yielded better results than medium and low rates; pulp mill sludge was the exception with no significant difference in plant performance between low and high rates. Suitable anthroposols for limestone quarry reclamation were achieved.

D'Orangeville, L., Côté, B., Houle, D. and Whalen, J. 2013. Reduced mineralizable carbon in a boreal forest soil after three years of artificial warming. Can. J. Soil Sci. 93: 567-572. Soil warming is expected to reduce organic carbon pools. We incubated soils from a balsam fir stand previously subjected to 3 yr of in situ experimental warming ( 4°C). Mineralizable carbon was significantly reduced (16-25%) in heated soils, corresponding to a 0.4-0.8% decline in the organic carbon pool.

Nikièma, P., Buckley, K. E., Enns, J. M., Qiang, H. and Akinremi, O. O. 2013. Effects of liquid hog manure on soil available nitrogen status, nitrogen leaching losses and wheat yield on a sandy loam soil of western Canada. Can. J. Soil Sci. 93: 573-584. Manure can improve soil quality and enhance crop yields. However, excessive manure use may contribute to nitrate () leaching, particularly on coarse-textured soils. The objective of this study was to evaluate the effects of liquid hog manure (LHM) on wheat yield, soil available N and leaching on a sandy soil in Manitoba. Manure treatments included three rates of LHM applied to supply 64 (low), 128 (medium) and 192 kg N ha^-1 (high) in 3 consecutive years (2002-2004). Unamended plots were used as a control. Available nitrogen was measured three times during each growing season at soil depths of 0-15, 15-30, 30-60, 60-90, and 90-120 cm. Undisturbed soil core lysimeters were used to measure leaching. Crop yields (grain and straw), N-uptake and N use efficiency were assessed at the end of each growing season. In 2002 and 2003, LHM had little effect on wheat yield, N nutrition and leaching due to below-normal rainfall in both years. In contrast, in 2004 when precipitation was above normal, LHM amendment increased grain yield and plant N-uptake. Relative to the control, grain yield was 20, 30 and 50% greater in the low, medium and high manure-N plots, respectively. Manure increased soil available N concentration 1.2-, 1.3- and 1.7-fold and induced additional -N leaching of 4.7, 28.4 and 54.5 kg ha^-1 in the low, medium and high manure-N plots, respectively. Results suggest that LHM should be used with caution on sandy soils due to leaching potential in years of high precipitation and low crop yields in years of low precipitation.

He, Y., DeSutter, T., Hopkins, D., Jia, X. and Wysocki, D. A. 2013. Predicting EC_eof the saturated paste extract from value of EC_1:5. Can. J. Soil Sci. 93: 585-594. Many laboratories appraise soil salinity from measurement of electrical conductivity of 1:5 soil to water extract (EC_1:5) due to its simplicity. However, the influence of salinity on plant growth is mainly based on electrical conductivity of saturated paste extract (EC_e), so it is necessary to convert EC_1:5 to EC_e in order to assess plant response. The objectives of this research were to develop models relating EC_1:5 and EC_e under four different 1:5 equilibration methods: (1) shaking, (2) shaking plus centrifuging, (3) stirring, and (4) a United States Department of Agriculture-Natural Resources Conservation Service (2011) equilibration method. One hundred soil samples, which were all derived from glacial parent materials in North Dakota, USA, were selected for this study. Non-transformed, non-transformed separated, ln-transformed, and exponential models were developed between EC_1:5 and EC_e. Non-transformed, simple linear regression models had obvious segments for all equilibration methods and the residual distributions varied. Therefore, data were separated at EC of 4 dS m^-1 and a quadratic curvilinear model was developed for relating EC_1:5 and EC_e (r² values ranged from 0.87 to 0.93) when EC_e values were less than 4 dS m^-1. Although the linear model was significant (P<0.05), soils having EC_e greater than 4 dS m^-1 had r² values less than 0.61. Across all soils, the ln-transformed model had r² values greater than 0.85, which was greater than the non-transformed or exponential models. By comparison of r², RMSE, and relative percentage difference, the separated curvilinear model that was established when salinity is less than 4 dS m^-1, and ln-transformed models were superior at predicting EC_e from EC_1:5 data compared to non-transformed and exponential models. These results indicate that across all equilibration methods EC_e can reliably be predicted from EC_1:5 data for soils from this region.

Masso, C. et Khiari, L. 2013. Expression et prédiction du pouvoir tampon des amendements et des engrais organiques. Can. J. Soil Sci. 93: 595-606. Le pouvoir tampon (PT) des substances organiques utilisées en agriculture comme amendement des sols ou comme engrais organiques est d'une grande importance pour contrôler l'effet néfaste des engrais minéraux dans la bande de placement à proximité des semences ou des jeunes plantules. Il s'agit d'effet de toxicité ammoniacale, nitreuse ou aluminique causé par la variation brusque et temporaire de pH suite à l'application de ces engrais. En revanche, à notre connaissance, il n'y pas de méthode de référence de quantification du PT des substrats organiques. Dans cette étude, une méthode par calcul intégral notée PT_I a été mise au point et testée sur 30 amendements et engrais organiques (AEO) couramment utilisés en agriculture au Québec. Ces AEO étaient titrés avec des quantités croissantes de H₂SO₄ ou NaOH dilué. Deux expressions linéaire et ponctuelle du PT obtenues de la littérature ont été comparées à la méthode PT_I qui s'est avérée plus appropriée aux courbes de titrage des AEO, particulièrement pour établir le PT global, incluant à la fois les traitements acide et basique, approche inapplicable avec les deux expressions obtenues de la littérature. En moyenne, l'alcalinité potentielle des 30 AEO était plus élevée que l'acidité totale échangeable. Le PT_I global était prédictible à l'aide du Ca total, du Ca échangeable et du Al total (r²=0,79). De même, le PT_I à l'acidité pouvait être prédit en utilisant le Ca total, le Ca échangeable et le pH_CaCl2 (r²=0,78).

St. Luce, M., Ziadi, N., Zebarth, B. J., Whalen, J. K., Grant, C. A., Gregorich, E, G., Lafond, P., Blackshaw, R. E., Johnson, E. N., O'Donovan, J. T. and Harker, K. N. 2013. Particulate organic matter and soil mineral nitrogen concentrations are good predictors of the soil nitrogen supply to canola following legume and non-legume crops in western Canada. Can. J. Soil Sci. 93: 607-620. Accurate estimation of potential nitrogen (N) availability from preceding crops is essential to improve N fertilizer management in agricultural soils. Labile organic N fractions such as microbial biomass N (MBN), water-extractable organic N (WEON), particulate and light fraction organic matter N (POMN, LFOMN) are sensitive to management-induced changes and have the potential to predict N availability. This study assessed the impact of preceding legume [field pea (Pisum sativum L.), faba bean (Vicia faba L.), faba bean green manure] and non-legume crops [canola (Brassica napus L.) and wheat (Triticum aestivum L.)] on labile organic N fractions, mineral N (NH₄-N NO₃-N), potentially mineralizable N (N₀) and soil N supply (canola grain yield and N uptake), and whether these soil parameters for the top 15 cm of soil could be used as indicators of soil N supply across no-till sites in western Canada. Labile organic N fractions and N₀ were similar regardless of preceding crop. Soil N supply was greatest following faba bean green manure at four of five sites. POMN was the best single predictor of soil N supply (R²=0.56 and R²=0.69 for yield and N uptake, respectively). Soil N supply was primarily related to the combined effects of POMN, mineral N and sand content, which explained 68 and 71% of the variation in grain yield and N uptake, respectively. This study demonstrated that POMN and mineral N are relatively good predictors of soil N supply to canola in western Canada. Accounting for these parameters as well as soil texture may help improve N fertilizer recommendations for canola.

Whitfield, C. J. and Reid, C. 2013. Predicting surface area of coarse-textured soils: Implications for weathering rates. Can. J. Soil Sci. 93: 621-630. The surface area of soil is an important determinant of mineral weathering rates, but is infrequently measured. Simple texture-based pedotransfer functions (PTFs) have been used to predict the specific surface area (SSA) of coarse-textured soils. Detailed physicochemical properties of 40 upland forest mineral soils from northeastern Alberta were used to evaluate three texture-based PTFs and to calculate weathering rates using a process-oriented soil-chemical model. Evaluation of the PTFs demonstrated that these equations predict only across a limited range of (low) surface areas. Moreover, the fit between predicted and measured SSA was generally poor for soils in this region of Alberta. Improved prediction of SSA was possible using a texture-based PTF calibrated for the region, although differences between measured and predicted values were often large. Mineralogy terms were used in a more comprehensive PTF to account for mineral-specific differences in surface area. This approach proved superior to texture-only approaches; however, it could not be used reliably for site-specific predictions (NRMSE=0.41). Soil-chemical model-generated weathering rates were strongly influenced by the SSA method used in parameterization; weathering estimates and corresponding critical load assessments based on measured SSA (and to a lesser extent SSA derived from the regional PTF) were the most robust. Methods for SSA prediction should be used with caution, particularly in cases where they are applied to soils with different character than those for which they were developed.

Liu, C. Y., Jiang, X., Fan, J. L. and Ziadi, N. 2013. Hexachlorobenzene accumulation in rice plants as affected by farm manure and urea applications in dissimilar soils. Can. J. Soil Sci. 93: 631-638. The key issue of the environmental effects of hexachlorobenzene (HCB) in soil is its bioavailability. A pot experiment was conducted to evaluate the bioavailability of HCB to roots, shoots and grains of rice (Oryza sativa L.), and to determine the effect of farm manure and urea applications on HCB accumulation in rice plants. Two soils, Hydragric Acrisols (Ac) and Gleyi-Stagnic Anthrosols (An), were used. The HCB concentrations in roots were 12 to 17 and 35 to 48 times those in shoots and grains, respectively. The application of 1 and 2% farm manure to both Ac and An decreased the bioconcentration factor of HCB for rice roots, suggesting that farm manure supply decreased HCB bioavailability. The application of 0.03 and 0.06% urea in both tested soils decreased HCB concentrations in rice shoots and roots; these decreases were attributed to the acceleration of HCB degradation by urea supplies. The effect of farm manure and urea supplies on rice grain uptake of HCB was negligible, owing to the small amount of HCB translocation from roots to grains. Because of the higher HCB degradation rate for An, HCB accumulation amounts in rice plants were lower for An than for Ac. In contrast, the bioconcentration factor of HCB was higher for An, suggesting that HCB bioavailability was higher in An than in Ac. The results show that HCB translocation from rice roots to grains was difficult, and that farm manure, urea and soil type all play important roles in HCB accumulation in rice plants.

Maas, S. E., Glenn, A. J., Tenuta, M. and Amiro, B. D. 2013. Net CO₂and N₂O exchange during perennial forage establishment in an annual crop rotation in the Red River Valley, Manitoba. Can. J. Soil Sci. 93: 639-652. The long-term use of perennial forages in crop rotations can increase soil carbon (C) and lower nitrous oxide (N₂O) emissions compared with continuous annual cropping. However, less is known of the short-term (within 2 yr) benefit of inclusion of perennial forages in an annual crop rotation on net carbon dioxide (CO₂) and N₂O fluxes. Perennial forage, primarily composed of alfalfa (Medicago sativa L.) and a minor component of timothy grass (Phleum pretense L.) was sown in 2008 on two 4-ha plots previously in annual cropping in the Red River Valley, Manitoba. Spring wheat (Triticum aestivum L.) and industrial rapeseed (Brassica napus L.) were grown on two adjacent plots in 2008 and 2009, respectively. Carbon dioxide and N₂O fluxes were measured continuously using the flux-gradient micrometeorological method from 2008 May 01 to 2010 Apr. 30. During the 2-yr study, the newly established perennial forage was nearly twice the sink for atmospheric CO₂ (mean and standard deviation of 4480±1840 kg C ha^-1) as the annual crops (2470±700 kg C ha^-1). The annual crop emitted more than four times the N₂O (7.8±0.7 kg N ha^-1) as the perennial forage stand (1.8±0.7 kg N ha^-1). When accounting for harvest C removals (grain, straw, hay) and considering the greenhouse gas (GHG) emissions in CO₂-equivalents (eq.), the newly established perennial forage was a net sink of 8470±5640 kg CO₂-eq. ha^-1 and the annual crop was a source of 3760±2450 kg CO₂-eq. ha^-1 during the study. The results indicate an immediate reduction in soil GHG emissions with the inclusion of perennial forage in the rotation, primarily from reduced N₂O emissions, the lack of crop removal in the forage establishment year and the longer growing season period of net CO₂ uptake of the perennial crop.