Xie, H. T., Yang, X. M., Drury, C. F., Yang, J. Y. and Zhang, X. D. 2011. Predicting soil organic carbon and total nitrogen using mid- and near-infrared spectra for Brookston clay loam soil in Southwestern Ontario, Canada. Can. J. Soil Sci. 91: 53–63. Mid-infrared (MIR) and near-infrared (NIR) spectroscopy of soils have been tested to estimate soil organic carbon (SOC) and total N (TN) concentrations at local, regional and national scales. However, these methods have rarely been used to assess SOC and TN concentrations of the same soil under different management practices. The objective of this study was to determine if models developed from infrared spectra of Brookston clay loam soils under different management practices could be used to estimate SOC, and TN concentrations and the C:N ratio. Soils used for model calibration included 217 samples from a long-term fertilization and crop rotation study and a long-term compost study, whereas 78 soil samples from a long-term tillage study on the same soil type were used for model validation. Soil organic carbon and TN concentrations of all samples were also analyzed using dry combustion techniques. Soil samples were scanned from 4000 to 400 cm−1 (2500–25 000 nm) for MIR spectra and from 8000 to 4000 cm−1 (1250–2500 nm) for NIR spectra. Partial least squares regression (PLSR) analysis was used for the calibration dataset to build prediction models for SOC, TN and C:N ratio. The SOC and TN concentrations determined using dry combustion techniques were compared with the prediction from the models using the calibration datasets. The predictions of SOC and TN concentrations by the PLSR method using infrared spectra were statistically sound, with high coefficient of determination with the calibration dataset (R2cal, SOCMIR=0.99 and SOCNIR=0.97, TNMIR=0.98 and TNNIR=0.97) and the validation dataset (R2val, SOCMIR=0.96 and SOCNIR=0.95, TNMIR=0.96 and TNNIR=0.95) and low root mean square error (RMSEPcal, SOCMIR=0.93 and SOCNIR=1.60, TNMIR=0.08 and TNNIR=0.12; RMSEPval, SOCMIR=1.40 and SOCNIR=1.75, TNMIR=0.11 and TNNIR=0.12). The predictions of SOC and TN concentrations in the 5 to 30 cm depth were better than the predictions for either the surface (0 to 5 cm) soils or for soils from lower depths (>30 cm). The models could be used as an alternative method for determining SOC and TN concentrations of Brookston clay loam soils; however, larger sample populations and improved model algorithms could further improve predictions.

X. M. 2015. Temporal effects of food waste compost on soil physical quality and productivity. Can. J. Soil Sci. 95: 251Á268. The benefits of compost additions on soil organic carbon content and crop productivity are extant in the literature, but detailed studies of compost effects on soil physical quality (SPQ) are limited. The objective of this study was therefore to describe how one-time additions of compost impact the immediate, mid-term and long-term SPQ and crop yields of an agricultural soil. Food waste compost (FWC) was incorporated once into the top 10 cm of a humid-temperate Brookston clay loam soil at rates of 0 (Control), 75 dry t ha(1 (FWC-75), 150 dry t ha(1 (FWCÁ150) and 300 dry t ha (1 (FWC-300); measurements of SPQ parameters and corn yield were then made annually over the next 11 yr. The SPQ parameters included bulk density (BD), organic carbon content (OC), air capacity (AC), plant-available water capacity (PAWC), relative field capacity (RFC), and saturated hydraulic conductivity (K S ), which were obtained from intact (undisturbed) soil core samples. Prior to compost addition, BD, OC, AC, PAWC, RFC and K S were substantially non-optimal, and BD had increased relative to virgin soil by 46%, while OC, AC and PAWC had decreased relative to virgin soil by 60, 56 and 43%, respectively. Improvements in SPQ 1 yr after compost addition were negligible or small for FWC-75 and FWC-150, but FWC-300 generated optimal values for BD, OC, AC, PAWC and RFC. The SPQ parameters degraded with time, but 11 yr after compost addition, OC and AC under FWC-300 were still within their optimal ranges, as well as significantly (PB0.05) greater than the Control values by 65 and 26%, respectively. Soil cracks and biopores apparently induced substantial annual variation in K S , but average K S nevertheless increased with increasing compost addition rate. Corn grain yield varied substantially among years, which was likely due to weather and compost effects; however, 11-yr cumulative yields from the compost treatments were greater than the Control by 2200Á6500 kg ha (1 .

Yang, J. Y., Huffman, E. C., Drury, C. F., Yang, X. M. and De Jong, R. 2011. Estimating the impact of manure nitrogen losses on total nitrogen application on agricultural land in Canada. Can. J. Soil Sci. 91: 107–122. About 1 million tonnes (1 Tg=1012 g) of livestock manure N are applied to farmland in Canada each year. Comprehensive information on manure N production and losses from manure during on-farm storage, handling and field application is scarce, especially at a regional scale. However, manure N losses during storage and land application are of considerable concern with respect to nitrogen use efficiency and environmental pollution of air, soil and water. In this paper, manure N production, manure N losses during storage and land application and manure N mineralization from organic manure and the resultant manure N available for annual crops were estimated using the Census of Agriculture database, Farm Environmental Management Survey data and manure N loss factors obtained from the literature. A database of fertilizer N application rates for field crops was developed at the regional scale based on recommendations provided in agronomic extension bulletins and fertilizer N sales. Fertilizer N and available manure N (i.e., total manure N produced minus N losses plus N mineralized from manure applied in previous years) were allocated to each of 24 crops at the regional scale from 1981 to 2006. The amount of manure N produced in Canada increased by 18.7% from 0.928 Tg in 1981 to 1.102 Tg in 2006. We estimated that 35.6% of the manure N produced was immediately available to crops, 25.6% was lost during storage and land application and 38.8% was carried over to the next year as organic N. The amount of fertilizer N applied to crops increased dramatically from 0.928 Tg in 1981 to a peak level of 1.68 Tg in 2000. There were significant changes in manure N production and application to farmland both on a regional and a temporal basis.

Influence of compost source on corn grain yields, nitrous oxide and carbon dioxide emissions in southwestern Ontario. Can. J. Soil Sci. 94: 347Á355. The impacts of compost type on corn grain yields over 10 yr and N 2 O and CO 2 emissions in the first 3 yr after compost application were evaluated on a Brookston clay loam soil in Woodslee, ON. The treatments included yard waste compost (YWC), kitchen food waste compost (FWC), and pig manure compost (PMC), which were applied once in the fall of 1998 to field plots at a rate of 75 Mg ha (1 (dry weight basis) and no further applications occurred thereafter as well as a fertilized control treatment. Large application rates were examined to see if the various compost sources could have a lasting effect on soil C storage, N 2 O and CO 2 emissions and corn yields. Compost application significantly increased corn grain yields by 12.9 to 19.4% over 3 yr. However, after 10 yr, FWC was the only compost source which significantly increased yields by 11.3% compared with the fertilized control. Emissions of N 2 O and CO 2 varied with compost type, soil water content and time. Greater N 2 O emissions occurred in 1999 from PMC (5.4 kg N ha (1 ) than YWC (2.7 kg N ha (1 ) and FWC (1.3 kg N ha (1 ); however, the N 2 O emissions from the PMC were less than from YWC and FWC in 2001. The 3-yr average N 2 O emissions were significantly greater with PMC (2.7 kg N ha (1 ) and YWC (2.5 kg N ha (1 ) compared with the control (1.5 kg N ha (1 ). Hence, the timing of N 2 O emissions varied by compost type, but the overall losses were similar as the higher N 2 O losses in the first year with PMC were offset by the reduced losses with PMC in the third year. Significantly more CO 2 was produced from the FWC in 2000 and from PMC in 2001 than the control. Fleming, R. et Denholme, K. 2014. Influence de la source de compost sur le rendement du maı¨s-grain ainsi que sur les e´missions d'oxyde nitreux et de dioxyde de carbone dans le sud-ouest de l'Ontario. Can. J. Soil Sci. 94: 347Á355. Les auteurs ont de´termine´quel impact la nature du compost a eu sur le rendement du maı¨s-grain pendant dix ans, ainsi que sur les e´missions de N 2 O et de CO 2 durant les trois anne´es suivant l'amendement d'un loam argileux Brookston situe´a`Woodslee, en Ontario. Les traitements e´taient les suivants : compost de re´sidus de jardinage (CRJ), compost de de´chets alimentaires (CDA) et compost de fumier de porc (CFP) applique´s une seule fois a`des parcelles sur le terrain, a`l'automne 1998, a`raison de 75 Mg par hectare (poids sec). Aucune autre application n'a e´te´effectue´e par la suite; une parcelle fertilise´e servait de te´moin. On a opte´pour un taux d'application e´leve´en vue d'e´tablir si le type de compost exerce un effet durable sur le stockage du C dans le sol, sur les de´gagements de N 2 O et de CO 2 , et sur le rendement du maı¨s. L'application de compost a augmente´significativement le rendement du maı¨s-grain pendant trois ans, soit de 12,9 a`19,4 %. Apre`s dix ans toutefois, seul le CDA avait accru ...

Yang, J. Y., Huffman, T., Drury, C. F., Yang, X. M., De Jong, R. and Campbell, C. A. 2012. Estimating changes of residual soil nitrogen in Chernozemic soils in Canada. Can. J. Soil Sci. 92: 481–491. Chernozemic soils (Mollisols) account for approximately 68% of total farmland in the prairies and 54% of farmland in Canada. Although many field studies have focused on the importance of N in Chernozemic soils, few modelling studies have been conducted to examine the risk of N contamination to the environment The objective of this research was to estimate temporal and spatial changes in residual soil nitrogen (RSN) on Chernozemic soils at the 1:1 million regional scale. An annual N budget was developed for the study area for the period 1981 to 2006, using the Canadian Agricultural Nitrogen Budget (CANB v3.0) model. The difference between N inputs and outputs is considered RSN, which is defined as the inorganic N left in the soil after harvest. Average RSN levels in the sub-humid Black and Dark Gray Chernozemic soils increased from 7–9 kg N ha−1 in 1981 to 20–23 kg N ha−1 in 2006. Changes in RSN were much less pronounced in the arid and semi-arid Brown and Dark Brown soil zones, where average values increased from approximately 1 kg N ha−1 to 4–7 kg N ha−1 over 25 yr. Commercial fertilizer, manure and biological N2 fixation were the three main sources of the increased N inputs. Drought conditions also contributed to the surplus of N in some years by reducing crop growth and thus the amount of N removed in grain and forage crops. In Chernozemic soils, more careful use of chemical fertilizer N, improved manure N management and greater use of legume-cereal rotations are recommended as methods to maintain soil fertility and reduce nitrogen loss to the environment.