Ige, D. V., Sayem, S. M. and Akinremi, O. O. 2015. Nitrogen mineralization in beef- and pig-manure-amended soils measured using anion resin method. Can. J. Soil Sci. 95: 305-319. A major challenge facing the widespread use of manure is the uncertainty about its fertilizer equivalence. This study was carried out to determine the fertilizer equivalence of locally available manures in two soils in Manitoba. A randomized complete block design was adopted with six treatments [nitrogen fertilizer, a liquid swine manure (LSM), three solid beef manures (SBM) and a control] and four replicates. Each treatment was applied to a cylindrical soil column installed at the site at the rate of 100 kg ha^-1 of “available N”, and leached NO₃-N was captured by resin bags at the bottom of the cylinder. The soils and resin bags removed from the cylinders were sampled at 0, 1, 2, 4, 6, 8, 10, 14, and 18 wk following treatment application. Ammonium nitrogen in the amendments was nitrified within the first 2 to 3 wk with significant build-up of NO₃-N in the soil above the control (P<0.05). The greatest available N was in the fertilizer treatment, followed by the LSM and the smallest was in the SBM. The available N in the three SBM was statistically similar (P>0.05). Approximately 50% of the inorganic N in LSM was available during the growing season, while 68 to 100% of SBM inorganic N was available. Between 4 and 25% of the organic N in the three SBM was mineralized during the growing season. High soil moisture hindered N mineralization and enhanced N loss in the clay soil. LSM has the greatest fertilizer equivalence, with a mean of 65 to 68%, of the four manure types used. The fertilizer equivalence of the three SBM ranged between 42 and 59% and was influenced by the manure C:N ratio and the soil environmental conditions. Our study suggests the need to revise the assumptions regarding manure N availability by considering soil environmental factors in the estimation of available N.

Yavitt, J. B. 2015. Land use history determines non-native earthworm impacts on atmospheric methane consumption in forest soils, central New York State. Can. J. Soil Sci. 95: 321-330. I used complementary field and laboratory studies to examine the impact of two types of soil disturbance on net consumption of atmospheric methane (CH₄) in forest soils near Ithaca, New York. One type of disturbance is invasion of non-native earthworms that mix soil layers, and the other is agriculture, which reduces the pit-and-mound surface topography to a flat landscape. Measurements of CH₄ fluxes between soil and the atmosphere were made in autumn before seasonal leaf fall when earthworms had consumed all of the previous year's leaf fall, and revealed no impact by earthworms in the never-tilled soils. Although earthworms did lead to greater consumption of atmospheric CH₄ in the post-agriculture soils, the mean consumption rate was only -0.2 mg m² d^-1. Concentrations of atmospheric CH₄ in wormed soils were often greater than that in the atmosphere, suggesting that earthworms promote CH₄ production. In general, earthworms decreased soil permeability to gas diffusion. Post-agriculture soils also had faster CH₄ oxidation rates when incubated in the laboratory. The results taken together suggest that earthworm impacts on atmospheric CH₄ consumption depend on the history of soil disturbance.

Zettl, J. D., Huang, M., Barbour, S. L. and Si, B. C. 2015. Density-dependent calibration of multisensor capacitance probes in coarse soil. Can. J. Soil Sci. 95: 331-336. Coarse-textured reconstructed soils are utilized extensively in the reclamation of mining waste. Accurate and continuous sensing of soil water content is required to understand soil water dynamics and evaluate the hydraulic characteristics of these soils. The EnviroSCAN (Sentek Pty. Ltd, Australia) is a semi-permanent multisensor capacitance probe (MCP) capable of continuous measurement of volumetric water content (_v) and has been used to monitor reclamation soil cover performance. Calibration of these probes is required to improve the accuracy of field measurements. In this study, field and laboratory measurements were undertaken over a range of water contents and bulk densities to refine the relationship between _v and scaled frequency (SF) measured by the MCP. The manufacturer's calibration equation tended to underestimate _v under wet conditions (_v>0.35 cm³ cm^-3). Our experimental data showed that bulk density (_b) did affect the MCP calibration and consequently a new calibration equation that includes the effect of _b is developed using laboratory measurements and validated using field measurements. This equation provided the highest degree of correlation and the smallest standard deviation of prediction to measured values of _v for laboratory and field measurements, respectively. This calibration improves the application of the EnviroSCAN for coarse-textured soils such as those utilized in this study.

Gombault, C., Madramootoo, C. A., Michaud, A. R., Beaudin, I., Sottile, M. F., Chikhaoui, M. and Ngwa, F. F. 2015. Impacts of climate change on nutrient losses from the Pike River watershed of southern Québec. Can. J. Soil Sci. 95: 337-358. The impacts of climate change on water quality in the Pike River watershed, an important contributor of nutrient loads into the northern arm of Lake Champlain, were simulated for the time horizon 2041-2070. Four water quality scenarios were simulated using a calibrated version of the Soil and Water Assessment Tool (SWAT) customized to Québec agroclimatic conditions. Three of the scenarios were generated using climate data simulated with the Fourth-generation Canadian Regional Climate Model (CRCM4). The fourth scenario was generated using the climate simulated with the Arpege Regional Climate Model. Potential mean climate-induced changes in sediment, phosphorus, and nitrogen yield projected by these scenarios were then analyzed for the 2050 horizon. In addition, the impacts of the different sources of climate projection uncertainty were assessed by comparing climate model initial conditions, and climate model physical structure effects on the hydrochemical projections. Only one climate scenario projected a significant increase in mean annual total phosphorus [10 metrics tons (t) yr^-1 or 14%] and total nitrogen (260 t yr^-1 or 17%) loads. However, when shorter time spans (seasonal and monthly scales) were considered, several significant changes were detected, especially in winter. Sediment and nutrient loadings, in winter, were predicted to become three to four times higher than current levels. These increases were attributed to a greater vulnerability of soils to erosion in winter due to the decrease in the snowpack, early onset of spring snowmelt, a greater number of rainfall events, and snowmelt episodes caused by higher winter and spring temperatures.

Zebarth, B. J., Forge, T. A., Goyer, C. and Brin, L. D. 2015. Effect of soil acidification on nitrification in soil. Can. J. Soil Sci. 95: 359-363. This laboratory experiment examined the effect of elemental S-induced variation in soil pH (3.97-5.29) on nitrification enzyme activity and conversion of to . Nitrification rate generally decreased with decreasing soil pH, but still proceeded rapidly within the pH range (4.5 to 5.2) recommended for blueberry production, contrary to what is generally assumed.