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Estimating soil nitrogen (N) mineralization is critical to balance fertilizer N requirements and their environmental impacts. In this study, net N mineralization was examined in soils under different crop rotations with each phase of the rotation present every year with biologically based incubations in 2011 and 2015. Net N mineralization was significantly different among treatments when the current crop was soybean, and the effect was dependent upon the previous crop and the cropping sequence. In particular, net increases in inorganic N were greater when the previous crop was winter wheat with or without red clover than if it were corn, and greater for the first year of soybean compared with the second year for rotations with two consecutive years of soybean in the 2011 incubation. However, cropping history did not influence net soil N mineralization when the current crop was corn, winter wheat, or winter wheat with red clover. In 2015, the presence of red clover in the rotation increased net N mineralization in all phases of the rotation. These results suggest both current and previous crops should be considered when estimating the N supplying capacity (net mineralization) of the soil. Net mineralizable N was found to be significantly correlated with total amino sugars (P

Soil water repellency (SWR) was measured for a 28 yr field study under irrigation on a clay loam Dark Brown soil in southern Alberta. The objectives were to study the effect of legume–cereal crop rotations, feedlot manure, and phosphorus (P) fertilizer application on soil hydrophobicity (SH) and soil water repellency index (RI) under irrigation. Mean SH and RI were similar (P > 0.05) for a legume–cereal and cereal rotation and were unaffected by P fertilization. However, P fertilization shifted the RI classification from slight to subcritical. In contrast, SH was significantly greater for manured than nonmanured treatments, while RI was unaffected. Soil organic carbon (SOC) concentration was significantly (P ≤ 0.05) correlated with SH (r = 0.74), but not with RI (r = −0.17). This suggested a closer association between the quantity of SOC and quantity of hydrophobic compounds (SH method) compared with the hydrophobic coatings inhibiting infiltration of water (RI method). No significant correlation between SH and RI (r = −0.09) suggests that SH is not a good predictor of SWR using the RI method. Overall, manure application increased SH and P fertilization shifted the RI classification from slight to subcritical. In contrast, legume–cereal rotations had no influence on SH and SWR using RI method compared with continuous cereal.

Ammonia (NH3) volatilization from NH3-based fertilizer and animal manure reduces their nitrogen (N) fertilizer value and is a source of environmental pollution. Mixing manure with biochar may lower NH3 volatilization from manure by adding H+, adsorbing mineral N, or increasing N immobilization in microbial biomass. The objective of this study was to determine whether wood-based biochar could lower NH3 volatilization from vented pails containing manure (liquid swine, dairy slurry, and solid poultry manure) or a urea ammonium nitrate solution (UAN). Two types of wood-based biochar (BlueLeaf and Dynamotive) were mixed with three types of manure and UAN fertilizer solution at 0, 2.5, 5, 10, and 25% biochar by volume in vented pails. After 21 d storage in an outdoor shaded area, the greatest NH3 volatilization was from poultry manure, which had pH 9.4 on average and low water content regardless of the biochar source and application rate. There was less NH3 volatilization from UAN fertilizer solution when mixed with 25% (v/v) of Dynamotive biochar compared with NH3 volatilization from UAN fertilizer solution mixed with 0%–10% (%) of Dynamotive biochar, probably because pH decreased from 7.0 to 6.4 after 21 d contact. Mixing wood-based biochar with manure had no impact on NH3 volatilization, suggesting that these biochar sources did not appreciably change the pH and N dynamics in stored manure after 21 d.

Warmer atmospheric temperatures (eT) will increase plant nutrient uptake, and elevated atmospheric CO2 (eCO2) is expected to enhance plant growth, whereas a multicomponent eTeCO2 effect should also be beneficial for agroecosystems. Our goal was to understand if single- (eT, eCO2) or multicomponent (eTeCO2) climate effects, predicted for southern Ontario, Canada, will affect soybean and soil properties differently when soil is amended with manure and biochar (MB) or with manure, nitrogen (N) fertilizer, and biochar (MNB) compared with the addition of manure and N fertilizer (MN). We hypothesized that biochar regulates climate effects and causes soybean and soil properties to be similar to ambient climate conditions than soil without biochar. However, soil amended with biochar functioned independently of single- or multicomponent climate effects. Soybean pod and shoot biomass, shoot height, and shoot:root ratio were greater (p 2 increased (p 4+ and NO3−), and the C/N ratio but increased (p

Liquid hog manure (LHM) and solid cattle manure (SCM) co-applied with biochar could beneficially influence soil nitrogen (N) and phosphorus (P) dynamics. A split-plot design was used at two sites (Brown and Black) in Saskatchewan to assess LHM and SCM (100 kg N·ha−1) applied alone or in combination with biochars (8 Mg carbon·ha−1) produced using slow or fast pyrolysis. Crop growth and nutrient uptake, along with fertilizer 15N recovery, were followed over four years in a cereal–oilseed rotation. Crop growth on the Brown soil was more responsive to the treatments than the Black soil, reflecting lower fertility of the Brown soil. The manure and biochar, applied alone or in combination, had little impact on available soil P. Manure and biochar effects on crop growth and nutrient uptake were attributed to temporal effects on soil N immobilization–mineralization influencing plant-available soil N. A negative impact of the fast pyrolysis biochar on growth and plant uptake was observed and attributable to its greater labile-carbon content, which likely promoted soil N immobilization. Synergism observed between SCM and the slow pyrolysis biochar may reflect enhanced net SCM-N mineralization and increased water-holding capacity. The majority (55%–80%) of plant 15N recovery occurred during the first year, with 86% of fertilizer 15N conserved within the soil–plant system after four years. Greater (40%) plant 15N recovery without biochar addition, coupled with increased (38%) soil 15N recovery with added biochar, suggests biochar-related immobilization and (or) sorption in the biochar-amended soils.

Crested wheatgrass (CWG) [Agropyron cristatum (L.) Gaertn.] is a commonly introduced grass in the Canadian prairies, but concerns remain about its possible long-term effects on soil quality, and its influence on soil water repellency (SWR) has not been determined. The long-term (24 yr) effects of CWG on SWR in comparison to seeded native grasses and annual cropping were determined for a clay loam soil in southern Alberta, Canada by measuring SOC concentration and SWR using soil hydrophobicity (SH) and soil water repellency index (RI) methods. The cropping treatments were CWG, seeded native grass mix (NGM), continuous wheat, and wheat–fallow rotation, each with fertilized (nitrogen) and non-fertilized subplots, replicated four times. Mean SOC concentration, SH, and RI in samples of surface soil were similar (P > 0.05) for CWG and seeded NGM, and they did not support our hypothesis (seeded NGM > CWG). Mean SOC was significantly greater for seeded perennial grasses than annual crops by 1.7–2 times and SH by 2.1–2.5 times, which supported our hypothesis, but RI was similar among treatments. As expected, nitrogen fertilization significantly increased SOC concentrations, but the effects on SH and RI were undetectable. A strong positive correlation occurred between SOC concentration and SH (r = 0.92) but not for RI (r = 0.10). Our findings suggested that SWR was similar for CWG and seeded NGM. The SWR as measured using SH was greater for seeded perennial grasses than annual cropping but was similar using RI.

Predicting the soil-available nitrogen (N) to grain corn over a growing season in humid temperate regions is the key for improving fertilizer N recommendations. The objective of this study was to evaluate a suite of soil-N tests to predict soil N availability to grain corn over two growing seasons at 13 individual sites with long-term history of synthetic N fertilization in Ontario, Canada (13 site-years). At each site, fertilizer N was applied at various rates (0–224 kg N·ha−1) to determine the crop response to N fertilizer, relative yield (RY), and the most economic rate of N (MERN). Across the entire dataset, water-extractable mineral N (WEMN) was the only soil test that strongly correlated to both RY (r = 0.74**) and MERN (r = −0.56*) indicating that in grain corn fields with long-term history of N fertilization, mineral forms of N in soil solution can be used for fertilizer N recommendations in southern and eastern Ontario. We also provide evidence that grouping soils based on clay content could further refine fertilizer-N recommendations for grain corn in Ontario. A multi-year validation of the WEMN test with more field sites and development of a fertilizer recommendation table for this soil test are recommended.

A 2 yr field study was conducted on a coarse-textured soil in Manitoba, Canada, to investigate the effects of liquid hog manure (LHM) and chemical fertilizer application on barley (2005) and red spring wheat (2006) yields, crop nutrient uptake, and nitrogen (N) and phosphorus (P) movement to the environment. The treatments were LHM applied at two rates as 22 000 L·ha−1 (2500 gal·ac−1, abbreviated as M2500) and 43 000 L·ha−1 (5000 gal·ac−1, abbreviated as M5000) and two rates of chemical fertilizer to match total N and P in LHM treatments, F2500 and F5000, along with an unamended control. The M5000 and M2500 treatments showed similar grain yield and N and P uptake. However, M5000 and M2500 significantly increased grain yield by 67% and 78%, respectively, compared with the control in 2005. In 2006, wheat grain yields from M2500 and M5000 were 71% and 86% greater than the control. In 2005, leachate NO3-N concentrations and leaching loads were higher with chemical fertilizers than M2500. In 2005, the apparent recovery of applied N as leachate was 35% and 23% in F5000 and F2500 treatments, whereas it was 6% and 7% of applied N in M5000 and M2500 plots, respectively. However, the application of M5000 resulted in P accumulation near the surface and may increase the potential risk of P loss with runoff. Our results show that applying LHM at moderate rates (M2500) may ensure desirable crop yields comparable to higher rates of nutrient application with minimal potential losses relative to higher rates.

Fall-applied manure may have nitrogen (N) fertilizer value for spring-seeded crops. We applied liquid or solid cattle manure to plots on a sandy-loam soil in southern Quebec in fall. The following spring, half of each plot received urea fertilizer before planting the spring cereal crop. Total N content of the spring cereal at tillering, flowering, and maturity was lower in subplots without urea, and yields were up to 183% less in the no-urea subplots, regardless of whether liquid or solid manure was applied in fall. Fall-applied manure did not provide plant-available N to spring cereals under our growing conditions.

Elemental sulfur (ES) fertilizers have high S content but may not be effective in the year of application due to the time required to oxidize. Rapid oxidation may be possible if the ES has a large surface area in contact with the soil. We evaluated the efficacy of Sulgro 70, a micronized ES fertilizer that is sprayed onto the soil surface, in eight field trials in southern and central Alberta over a 2 yr period. Under dry conditions in southern Alberta, the relative efficacy of Sulgro 70 to increase S supply to ion-exchange membranes was 22% during the first 4 wk period after seeding and 53% during the second 4 wk period after seeding, compared with ammonium sulfate (AS) sprayed on the soil surface. Under wetter conditions in central Alberta, the relative efficacy of Sulgro 70 to increase S supply was variable (51%–201%) during the first 4 wk period after seeding and 56% during the second 4 wk period after seeding. Based on increases in biomass S concentration in three trials where the unfertilized control had low S concentration (−1), the relative efficacy of Sulgro 70 was 34%. Canola seed yield was not increased by application of AS or Sulgro 70 in any of the trials. Sulgro 70 sprayed on the soil surface oxidized appreciably during the first 8 wk after seeding and, with suitable management, has the potential to meet canola S requirements in the year of application.

The overuse of agrochemicals for agricultural productivity to meet the global food demand of the rapidly growing human population is a great environmental threat, particularly for aquatic ecosystems. Being associated intimately with plant health, growth, and productivity, the plant microbiome is emerging as a promising environmentally friendly and sustainable resource for agricultural productivity. For the past decades, our understanding of the interactions between plants and microorganisms and our knowledge of how to improve the plant microbiome by using microbial inoculants has increased significantly. A better understanding of the impact of the plant microbiome on mineral resources will benefit plant and soil health. In this review, we highlight the importance of microbial inoculants and their interactions with mineral fertilizers in enhancing crop productivity, as well as current challenges.

Forested reclamation of oil sand mines in northern Alberta often use peat salvaged from lowland organic soils as a coversoil during soil reconstruction of man-made landforms. Previous studies suggest that planted tree seedlings may be limited in part by low phosphorus (P) and potassium (K) availability in peat. Fertilization is commonly used to treat nutrient limitations on reclamation sites; however, broad spectrum applications can induce strong competition from colonizing vegetation. This study explores the ability of a targeted application of individual macronutrients to (1) reduce nutrient deficiencies in peat coversoils and improve tree growth, while (2) minimizing the colonizing competition. Liquid fertilizer was applied to 6-yr-old aspen, pine, and spruce trees in the field using five nutrient combinations: control (no fertilizer), NPK, PK, P, and K. Tree growth, foliar nutrient concentrations, vegetation cover, and environmental parameters were monitored over two growing seasons. Aspen responded the strongest to fertilization, particularly in the P treatment, whereas pine and spruce marginally responded to NPK. Competing vegetation increased in the NPK but did not respond to the P and K treatments, indicating targeted fertilization can reduce colonizing competition. Additional analyses of the soil conditions of the site suggest that other factors were potentially more limiting to the trees during the study. Targeted fertilization of forest reclamation sites at a later stand age can be an option to improve efficacy and cost savings; however, response will also depend on other site (e.g., soil pH, precipitation, and soil water content) and management (e.g., fertilizer application rate) factors.

Fertilizer NO3-N may represent a benefit over NH4-N containing sources in semiarid regions where rainfall is often not sufficient to leach fertilizer-N out of crop rooting zones, denitrification concerns are not great, and when NH3 volatilization concerns exist. The objective of our study was to contrast plant-N derived from fertilizer-15N (15Ndff), fertilizer-15N recovery (F15NR), total N uptake, grain yield, and protein of wheat (Triticum aestivum L.) from spring-applied NaNO3 relative to urea and urea augmented with urease inhibitor N-(n-butyl)thiophosphoric triamide (NBPT). We established six fertilizer-N field trials widespread within the state of Montana between 2012 and 2017. The trials incorporated different experimental designs and 15N-labeled fertilizer-N sources, including NaNO3, NH4NO3, urea, and urea + NBPT. Overall, F15NR and 15Ndff in mature crop biomass were significantly greater for NaNO3 than urea or urea + NBPT (P 15Ndff averaged 53.8%, 43.9%, and 44.7% across locations for NaNO3, urea, and urea + NBPT, respectively. Likewise, crop F15NR averaged 52.2%, 35.8%, and 38.6% for NaNO3, urea, and urea + NBPT, respectively. Soil 15N recovered in the surface layer (0–15 cm) was lower for NaNO3 compared with urea and urea + NBPT. Wheat grain yield and protein were generally not sensitive to improvements in 15Ndff, F15NR, or total N uptake. Our study hypothesis that NaNO3 would result in similar or better performance than urea or urea + NBPT was confirmed. Use of NO3-N fertilizer might be an alternative strategy to mitigate fertilizer-N induced soil acidity in semiarid regions of the northern Great Plains.

Agricultural ecosystems are one of the largest global contributors to nitrate (NO3−) contamination of surface- and groundwater through fertilizer application. Improved fertilizer practices are needed to manage crop nutrient supply in corn (Zea mays L.) while minimizing impacts to clean water reserves. The goal of this study was to compare current nitrogen (N) fertilizer practices (urea at planting) with “packages” of improved management practices (a combination of right timing and product) that farmers potentially use. We conducted measurements in a continuous corn system from November 2015 to May 2017 at a large field scale (four 4 ha plots). Nitrate concentration was measured below the root zone and drainage estimated using a soil water budget approach in which evapotranspiration was measured using the eddy covariance method. The objective was to compare NO3−-N leaching from fields receiving urea vs. urea + combination of nitrification and urease inhibitors (NUI) fertilizer applications at planting, urea–ammonium nitrate (UAN) vs. UAN + NUI applied at sidedress, and a combination of these practices: urea + NUI at planting vs. UAN at sidedress. Drainage was only significant in the non-growing season. Neither fertilizer products applied with NUI at planting or sidedress proved to significantly reduce NO3−-N leaching. The combination of delaying fertilization to sidedress and applying UAN significantly reduced the soil water NO3−-N concentration compared with urea + NUI at planting (mean of 5.2 vs. 6.7 mg L−1) but only in 2015–2016. Based on these results, applying UAN at sidedress is recommended, although additional study years are needed to confirm those results.

Erosion leads to substantial loss of soil productivity. To abate such decline, amendments such as manure or fertilizer have been successfully employed. However, the longevities of erosion and soil amendment legacy effects are not well quantified. In 1957, a Dark Brown Chernozem soil at Lethbridge, AB, was land-levelled, creating three degrees of topsoil removal or erosion: noneroded, moderate erosion, or severe erosion. Two amendment studies (1980–1985 and 1987–1991) were superimposed on the erosion treatments. Both studies were cropped to spring wheat (Triticum aestivum L.) from 1993–2010 to examine legacy effects of erosion and soil amendments on wheat yield and soil properties. Without amendment, mean wheat yield under moderate erosion was 40% of the noneroded treatment, whereas severe erosion was 34% of the noneroded treatment, 36–42 yr (1993–1999) after erosion. Under moderate or severe erosion, the restorative power of manure diminished substantially in the first 10–15 yr following cessation of addition, but then levelled off resulting in wheat yields up to 35% higher than equivalent nonamended treatments. Legacy effects of erosion (54 yr) and amendment (27–31 yr) on soil organic carbon and total nitrogen were also observed.

Soil organic carbon (SOC) changes slowly, and final management influences can be measured only after decades. Analysis of archived samples from a site established on grassland in 1911 showed that SOC, under wheat systems, approached steady state after several decades, and that its amount reflected the inputs of residue C.

Mining and natural resource development in the Canadian north has produced large areas of disturbance and volumes of waste, necessitating reclamation. This study focused on building anthroposols in a greenhouse using waste material from Diavik Diamond Mine. There were six substrates (crushed rock, lakebed sediment, processed kimberlite, and its combinations), seven organic amendments (sewage, soil, peat, Black Earth, biochar, and its combinations), a control, and two nutrient treatments (with and without fertilizer). Substrates and amendments were mixed and seeded with three grass species. Soil properties and vegetation responses were assessed. Substrate structure was a challenge; crushed rock and processed kimberlite had little fine material and lakebed sediment was compacted. Processed kimberlite and sewage had metal concentrations (barium, chromium, cobalt, copper, molybdenum, nickel, selenium, and zinc) above guidelines. Vegetation established on all anthroposols, with plant growth and density greatest in crushed rock, followed by 25% processed kimberlite with 75% lakebed sediment and 100% lakebed sediment. Substrates amended with peat and (or) soil had the greatest plant density and belowground biomass; substrates amended with sewage and sewage–soil had greatest aboveground biomass. Fertilizer had a limited effect. With appropriate amendments, waste materials at the mine showed potential as reclamation soils.

Elevated soil fertility levels induced by continuous chemical fertilizer and (or) manure application may affect N loss potential and redistribution within soil-crop system. A 49-d packed soil column experiment with a factorial design of three soil fertility levels and four fertilization treatments was conducted to evaluate the effects of soil fertility and fertilization treatments on the accumulation and leaching risk of reactive N. The results showed that the 49-d cumulative leaching loss of total reactive N ranged from 176.3 to 499.0 kg N ha−1. The cumulative leaching losses of total dissolved nitrogen (TDN) and dissolved organic nitrogen (DON) in NPK treatment were significantly higher than those in other three treatments in fertility level I and II soils. The cumulative leaching loss of NO3−-N was significantly greater in NPK + M or NPK treatment than in CK treatment in fertility level I or III soils, and it was remarkably greater in M treatment than in other three treatments in fertility level II soil. In total, 64.0% of TDN in soil leachate existed in the form of DON, and 35.1% was nitrate-N among different soil fertility and fertilization treatments. These results indicated that DON was an important component of N leaching loss and could not be neglected in sustainable development of vegetable greenhouse soil.

Inadequate and (or) inconsistent soil sample preparation techniques (SPT) contribute to excessive variance, difficulties in soil test interpretation, and incorrect lime and fertilizer recommendations. The objective of this study was to evaluate the effect of SPT of five laboratories in Quebec (Canada) on chemical parameters measurement reliability. Samples of fine (G1), medium (G2), and coarse (G3) textured soils were collected from the surface layer. Three 500 g portions of each soil were sent to each laboratory for preparation. In addition, all samples were analyzed by the same laboratory for routine analyses. Nested ANOVA in a hierarchical model were performed with components of SPT interlaboratory reproducibility, SPT intralaboratory replicability, and intralaboratory soil analysis repeatability. Before samples were analyzed, we observed an important interlaboratory heterogeneity of particle size distributions for the same samples; due to sample preparation techniques, this can affect results of the analyses. Of all variables analyzed, the only significant, outside acceptable variations due to SPT were (1) pHwater in G1; (2) PM-III, AlM-III, and (P/Al)M-III in G1 and G2; (3) KM-III, CaM-III, MgM-III and organic matter in G3; and (4) MnM-III and CuM-III in G1, G2, and G3. The steps in SPT, mostly drying and crushing, require standardization to reduce the variance of the entire soil testing process.

Environmental indices for soil P limit P applications when soil tests and risk of P losses exceed a given threshold. Producers’ reluctance to reduce P inputs often stem from concerns regarding reduced crop production and soil fertility. Our objectives were to identify changes in soil P fractions after 4 yr of repeated manure or fertilizer P applications at rates ≤ crop removal by corn (Zea mays L.), and the impact of these applications on yields. Olsen P and soil P fractions extracted using a modified Hedley P fractionation procedure were measured. Corn yields were nonresponsive to P applications. After 4 yr, Olsen P was 16.6 and 24.6 mg kg−1 at the application rates of 0 and 33 kg P ha−1 yr−1, respectively, for the inorganic fertilizer treatment indicating that soil P drawdown was occurring. Only the most labile forms of Pi (resin and bicarbonate extractable) were affected by treatment, with greater values at higher P application rates. Adherence to Ontario’s P index recommendations for P applications at or below crop removal should not be a crop production concern. Furthermore, given the rate of soil labile P drawdown, routine soil testing (every 3–5 yr) would identify agronomically significant changes in soil test P before the crop yield is impacted.

The nitrogen (N) index for humid temperate southern Ontario, Canada (Ontario N index) incorporates previous and current crop type, fertilizer and (or) manure management, and hydrologic soil group (HSG) to estimate risk for contamination of tile drainage water and groundwater by nitrate leached below the primary crop root zone (top 60 cm of soil). The Ontario N index has received limited ground-truthing, and the leaching component was assessed using chloride tracer (ClTR) on five soils (one sandy loam, two loams, and two clay loams) representing four HSG-based risk levels (HSG-A, high risk; HSG-B, medium risk; HSG-C, low risk; HSG-D, very low risk). A square-wave pulse of ClTR was applied to the soil surfaces in fall 2007 as KCl, and movement and loss of ClTR was tracked over 1–1.2 years using monthly soil core samples collected from the top 60–80 cm. For all five soils, 60–96% of ClTR was leached out of the primary crop root zone (below 60 cm depth) during the noncropping period (October 2007 to March 2008 inclusive), and >80% was leached out of the root zone within 1 year. The percentage of ClTR that leached did not correlate with precipitation or HSG designation, but produced significant (P < 0.05) power function regressions with minimum and harmonic mean saturated soil hydraulic conductivity (Ksat) measured in the top 50–60 cm. ClTR leaching rate appeared to be controlled primarily by Ksat in a manner consistent with infiltration and solute transport theory. It was consequently proposed that solute leaching loss versus Ksat relationships may improve N index risk estimates for both southern Ontario and other humid temperate regions.

There is growing interest among commercial wine grape (Vitis vinifera L.) growers in reducing water and fertilizer consumption, but little information exists on how best to combine conservative irrigation and soil management practices in the vineyard. In a 3-year-old Merlot vineyard in the semi-arid Okanagan Valley, British Columbia, the interactive effects of resource-conserving micro-irrigation (drippers or microsprinkers), nutrient applications (fertigation or compost), and surface mulching (wood and bark chips) on nitrogen (N) and phosphorus (P) dynamics in the wetted zone of surface soils were examined throughout the growing season using ion-exchange resins. Treatment differences in soil carbon and major nutrient pools, temperature, and moisture were also measured. Higher NO3-N was adsorbed by resins buried under drippers than under microsprinklers except in mulched plots, where NO3-N was uniformly low. By enhancing soil carbon availability and moderating soil microclimate, surface mulches may have promoted microbial immobilisation of N. Compost applications increased soil ortho-P levels, especially on mulched plots, suggesting that both P inputs (from compost) and enhanced microbial biomass (from mulch) promoted soil P cycling. Future work will examine the interactive effects of these resource-efficient practices on leaching losses, greenhouse gas emissions, crop productivity, and fruit quality.

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−1of “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 (P0.05). 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.

Dessureault-Rompré, J., Zebarth, B. J., Burton, D. L. and Georgallas, A. 2015. Predicting soil nitrogen supply from soil properties. Can. J. Soil Sci. 95: 63–75. Prediction functions based on simple kinetic models can be used to estimate soil N mineralization as an aid to improved fertilizer N management, but require long-term incubations to obtain the necessary parameters. Therefore, the objective of this study was to examine the feasibility of predicting the mineralizable N parameters necessary to implement prediction functions and in addition to verify their efficiency in modeling soil N supply (SNS) over a growing season. To implement a prediction function based on a first-order (F) kinetic model, a regression equation was developed using a data base of 92 soils, which accounted for 65% of the variance in potentially mineralizable N (N 0) using soil total N (STN) and Pool I, a labile mineralizable N pool. However, the F prediction function did not provide satisfactory prediction (R 2=0.17–0.18) of SNS when compared with a field-based measure of SNS (PASNS) if values of N 0 were predicted from the regression equation. We also examined a two-pool zero- plus first-order (ZF) prediction function. A regression model was developed including soil organic C and Pool I and explained 66% of the variance in k S , the rate constant of the zero-order pool. In addition, a regression equation was developed which explained 86% of the variance in the size of the first-order pool, N L , from Pool I. The ZF prediction function provided satisfactory prediction of SNS (R 2=0.41–0.49) using both measured and predicted values of k S and N L . This study demonstrated a simple prediction function can be used to estimate SNS over a growing season where the mineralizable N parameters are predicted from simple soil properties using regression equations.

Agronomists in Manitoba, Canada, are willing to reduce soil nitrous oxide emissions. They consider: enhanced efficiency fertilizers if cost effective; both crop yield and financial returns to be important for application rate; preferred fall application instead of spring because of operational advantages; and using banding placement if appropriate equipment is available.

Managing nitrogen (N) inputs to sustain high yields while minimizing losses to adjacent environments remains among the foremost aims in agroecosystems. We studied the N balance in a study established in 1911 at Lethbridge, AB, Canada. The experiment includes three cropping systems — continuous wheat (W), fallow–wheat–wheat (FWW), and fallow–wheat (FW) — with a factorial of two N rates (0 and 45 kg N ha−1) and two phosphorus (P) rates (0 and 20 kg P ha−1) superimposed beginning in 1967. In unfertilized subplots, grain yields generally increased for the first eight decades, but then declined, perhaps partly because of growing N deficiency. Yield response to N increased over time, especially under continuous cropping and when co-applied with P. Soil N concentration in the surface 15 cm declined in the first few decades, and then approached an apparent steady state. Application of N increased soil N, roughly in proportion to the amount of residue returned. For the first half-century (1911–1967), N removal was...

Increasingly, poor soils are used for plant cultivation involving chemical fertilizer (CF) usage which in turn lowers soil quality. To improve the quality of poor soils, promote plant growth, and r...

Quantifying ammonia (NH3) flux following fertilizer and manure nitrogen (N) application is crucial to develop sound management practices. Traditional methods used for obtaining these measures are either expensive, inefficient, or inaccurate. The objective of this study is to develop a method using a passive dosimeter and a semi-open static chamber to provide an economical and simple solution to measure NH3 loss following nitrogen application. Dosimeter tubes were commercially developed to measure ammonia exposure, providing a time-weighted-average. In this study,chicken manure was applied to short grass and the ppm h reading obtained using the dositube ammonia method (DAM) was calibrated against a reference measure of NH3 loss (kg N ha-1) using a wind tunnel and acid trap method. A calibration was developed (Estimated Total Loss (kg N ha-1) = (0.217Dw) - (0.034D) + 0.71) which requires the dositube (D) to be read every 24 h and placed at a height of 0.15 m in the Dositube chamber, with wind speed (w, m s-...

Nitrous oxide (N2O) production in four soils with unique fertilization management histories — collected from long-term fertility treatments receiving no fertilizer, NPKS, PKS, and NPK in a 5 yr cer...

The effect of long-term (20 yr) fertilizer application on soil nitrogen (N) transformation in paddy soils was studied at three sites (Xinhua, Ningxiang, and Taojiang) in Hunan province, China. Four...

Roy, A. K., Wagner-Riddle, C., Deen, B., Lauzon, J. and Bruulsema, T. 2014. Nitrogen application rate, timing and history effects on nitrous oxide emissions from corn (Zea mays L.). Can. J. Soil Sci. 94: 563–573. Nitrous oxide (N2O) emissions resulting from application of nitrogen (N) fertilizer contribute to the greenhouse gas footprint of corn production. In eastern Canada, corn is a major crop with most N fertilizer applied pre- or at planting. This timing of application results in a lack of synchrony of soil N supply and crop N demand. Matching the amount and timing of application to crop uptake has been suggested as a mitigation measure to reduce N losses, and is an integral part of the 4R Nutrient Stewardship program. This study examined the effect of timing, rate and history of urea-ammonium nitrate application on N2O emissions in corn in 2011 and 2012 at Elora, ON, Canada. Treatments were three N rates (30, 145 and 218 kg N ha−1); two timings (N injected in mid-row at planting and at the 8th leaf stage, V8); two histories (short-term: applying N rate treatments on plots that had received 145 kg N ha−1in the previous year, and long-term: applying the same N rate to a given plot over the duration of the trial). N2O emissions were measured using static chambers. History of N application did not have an effect on N2O emissions or grain yield. In both years, cumulative N2O emissions during the growing season and corn yields increased significantly with increasing N application rates. In 2011, cumulative N2O emissions were significantly lower when N was applied as side-dress at V8 (0.88 kg N ha−1) compared with planting (2.12 kg N ha−1), with no significant impact on corn grain yield (average 9.1 Mg ha−1). In contrast, in 2012, limited rainfall reduced both N2O emissions and corn grain yield, and neither N2O emission (average 0.17 kg N ha−1) nor grain yield (average 6.7 Mg ha−1) was affected by timing of N application. Applying N as side-dress at V8 instead of at planting and using the recommended N rate were shown to be effective N2O emission mitigation practices without affecting corn yield during a typical wet spring in Ontario.

Drury, C. F., Reynolds, W. D., Tan, C. S., McLaughlin, N. B., Yang, X. M., Calder, W., Oloya, T. O. and Yang, J. Y. 2014. Impacts of 49–51 years of years of fertilization and crop rotation on growing season nitrous oxide emissions, nitrogen uptake and corn yields. Can. J. Soil Sci. 94: 421–433. A field study was established in 1959 to evaluate the effects of fertilization and crop rotation on crop yields, soil and environmental quality on a Brookston clay loam. There were two fertilizer treatments (fertilized and not-fertilized) and six cropping treatments including continuous corn (CC), continuous Kentucky bluegrass sod and a 4-yr rotation of corn–oat–alfalfa–alfalfa with each phase present each year. We measured N2O emissions, inorganic N and plant N uptake over three growing seasons (2007–2009) in the corn phase. Nitrous oxide emissions varied over the 3 yr as a result of the seasonal variation in precipitation quantity, intensity and timing and differences in crop growth and N uptake. Fertilized CC lost, on average, 7.36 kg N ha−1 by N2O emissions, whereas the not-fertilized CC lost only 0.51 kg N ha−1. Fertilized rotation corn (RC) lost 6.46 kg N ha−1, which was 12% lower than fertilized CC. The not-fertilized RC, on the other hand, emitted about half as much N2O (2.95 kg N ha−1) as the fertilized RC. Fertilized RC had corn grain yields that averaged 10.0 t ha−1 over the 3 yr followed by fertilized CC at 5.48 t ha−1. Not-fertilized RC corn had yields that were 61% lower (3.93 t ha−1) than fertilized RC, whereas the not-fertilized CC had yields that were 75% lower (1.39 t ha−1) than fertilized CC. Nitrous oxide emissions were found to be dramatically affected by long-term management practices and crop rotation had lower emissions in the corn phase of the rotation even though the N input from fertilizer addition and legume N fixation was greater. These N2O emission and yield results were due to both factors that are traditionally used to describe these processes as well as long-term soil quality factors, which were created by the long-term management (i.e., soil organic carbon, soil physical parameters such as bulk density, and porosity, soil fauna and micro-flora) and that influenced crop growth, N uptake and soil water contents.

Rasouli, S., Whalen, J. K. and Madramootoo, C. A. 2014. Review: Reducing residual soil nitrogen losses from agroecosystems for surface water protection in Quebec and Ontario, Canada: Best management practices, policies and perspectives. Can. J. Soil Sci. 94: 109–127. Eutrophication and cyanobacteria blooms, a growing problem in many of Quebec and Ontario's lakes and rivers, are largely attributed to the phosphorus (P) and nitrogen (N) emanating from intensively cropped agricultural fields. In fact, 49% of N loading in surface waters comes from runoff and leaching from fertilized soils and livestock operations. The residual soil nitrogen (RSN), which remains in soil at the end of the growing season, contains soluble and particulate forms of N that are prone to being transported from agricultural fields to waterways. Policies and best management practices (BMPs) to regulate manure storage and restrict fertilizer and manure spreading can help in reducing N losses from agroecosystems. However, reduction of RSN also requires an understanding of the complex interactions between climate, soil type, topography, hydrology and cropping systems. Reducing N losses from agroecosystems can be achieved through careful accounting for all N inputs (e.g., N credits for legumes and manure inputs) in nutrient management plans, including those applied in previous years, as well as the strategic implementation of multiple BMPs and calibrated soil N testing for crops with high N requirements. We conclude that increasing farmer awareness and motivation to implement BMPs will be important in reducing RSN. Programs to promote communication between farmers and researchers, crop advisors and provincial ministries of agriculture and the environment are recommended.