Dry bean (Phaseolus vulgaris L.), potato (Solanum tuberosum L.), wheat (Triticum aestivum L.), and sugar beet (Beta vulgaris L.) are mainstays of irrigated crop production in southern Alberta. Concerns about soil quality and sustainability instigated a 12 yr (2000–2011) rotation study to compare conventional (CONV) with conservation (CONS) management practices (reduced tillage, narrow-row dry bean, compost addition, and cover cropping). Plant-available water (PAW) was measured using a neutron probe (10–16 count days·season⁻¹, n = 148) on all phases of 4 yr (dry bean–potato–wheat–sugar beet) rotations under CONS and CONV management. A visual monitoring approach was used for irrigation scheduling. For dry bean and sugar beet, management allowable depletion (MAD) was exceeded on only 11%–15% of neutron probe count days over 12 yr. However, MAD was exceeded on 30% of count days for wheat and 43% for potato. Significant crop × management interactions showed that PAW was higher with CONS management most frequently on potato, followed by dry bean, wheat, and sugar beet. This order reflected the prevalence of CONS practices directly impacting each crop. Regression analyses showed that potato, wheat, and sugar beet yield increased significantly as mean growing season water table depth (WTD) increased. This was explained by yield suppression due to excessive soil wetness in seasons with high rainfall and shallow WTD. This study provided comparative soil water dynamics for four major irrigated crops in southern Alberta, over a 12 yr period, which included record high and low growing season precipitation.

Urease inhibitor [N-(n-butyl) thiophosphoric triamide (NBPT)] and nitrification inhibitor (NI) (3,4-dimethylpyrazole phosphate) have been used to reduce nitrogen (N) losses from urea-based fertilizers. This study evaluated the effect of temperature, NBPT, and NI on kinetic and thermodynamic properties of urea hydrolysis in six soils. Soils were amended (250 kg N·ha⁻¹) with urea (UR), NBPT treated urea (UR_NBPT), or NBPT + NI treated urea (UR_DI), incubated at 5, 15, or 25 °C, and destructively sampled eight times during an 18 d incubation. We measured urea hydrolysis rate by the disappearance of urea with time and determined the rate constant (k; d⁻¹) assuming first-order kinetics. Our results showed that k increased with temperature in the order of 0.07 (5 °C), 0.12 (15 °C), and 0.20 (25 °C) across soils and inhibitor treatments. In addition, k declined in the order of UR (0.19) > UR_DI (0.11) > UR_NBPT (0.08) across soils and temperatures. Although urease inhibitor, NBPT, increased the half-life of urea from 3.8 to 8.3 d across soil–temperature, the addition of a NI significantly reduced the half-life of NBPT treated urea by approximately 2 d across soil–temperature. Thermodynamics parameters showed that urea hydrolysis was nonspontaneous, and enthalpy and entropy changes were not significantly different among inhibitor treatments in five of the six soils. We conclude that the often-reported greater ammonia volatilization from UR_DI than UR_NBPT may not only be due to the persistence of ammonium in the presence of NI but also because NI reduced the inhibitory effect of NBPT on urea hydrolysis.

Burning biomass for energy generates ash that could be applied as a soil amendment to ameliorate acidity and mitigate nutrient losses associated with biomass harvesting. These soil improvements may also enhance tree growth and foliar nutrition. In this study, we applied low- and high-carbon wood-derived ash at rates of 0 (control), 1000, and 10 000 kg·ha⁻¹ (dry weight equivalents) to soils planted with Picea mariana (Mill.) B.S.P. and Picea glauca (Moench) Voss in a replicated (5) factorial design. We measured soil properties, tree seedling height, and foliar nutrient contents prior to and 4 mo after wood ash addition to determine the immediate effects on soil physical, chemical, and biological properties, and tree seedling performance. We conclude that there were no negative effects of applying either wood ash and that application of ash at 10 000 kg·ha⁻¹, particularly with the low-carbon ash, produced the greatest changes. We anticipate that changes may become more evident over the longer term, especially with respect to tree growth and nutritional responses (e.g., as nutrient uptake demand increases) once the seedlings become more established.

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 (<3 g S·kg⁻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.

There is a growing demand for standardized, easily accessible, and detailed information pertaining to soil and its variability across the landscape. Typically, this information is only available for selected areas in the form of local or regional soil surveys reports which are difficult, and costly, to develop. Additionally, soil surveying protocols have changed with time, resulting in inconsistencies between surveys conducted over different periods. This article describes systematic procedures applied to generate an aspatial, terminologically, and unit-consistent, database for forest soils from county-based soil survey reports for the province of New Brunswick, Canada. The procedures involved (i) amalgamating data from individual soil surveys following a hierarchical framework, (ii) summarizing and grouping soil information by soil associations, (iii) assigning correct soil associates to each association, with each soil associate distinguished by drainage classification, (iv) assigning pedologically correct horizon sequences, as identified in the original soil surveys, to each soil associate, (v) assigning horizon descriptors and measured soil properties to each horizon, as outlined by the Canadian System of Soil Classification, and (vi) harmonizing units of measurement for individual soil properties. Identification and summarization of all soil associations (and corresponding soil associates) was completed with reference to the principal soil-forming factors, namely soil parent material, topographic surface expressions, soil drainage, and dominant vegetation type(s). This procedure, utilizing 17 soil surveys, resulted in an amalgamated database containing 106 soil associations, 243 soil associates, and 522 soil horizon sequences summarizing the variability of forest soil conditions across New Brunswick.

Combined papermill biosolids (PB) and forest-derived alkaline by-products are known for their direct benefits to agricultural crops, but their residual effects after several years of application have received little attention. A 10 yr field study was initiated on a loamy soil at Yamachiche, QC, to assess the residual effects of PB application after nine consecutive years, either alone or with several liming by-products, on nitrogen (N), phosphorus (P), and metal accumulation in plant and crop yield. The treatments consisted of PB at 0, 30, 60, and 90 Mg wet·ha⁻¹, three liming by-products (calcitic lime, lime mud, and wood ash), each at 3 Mg wet·ha⁻¹ with 30 Mg wet PB·ha⁻¹, and a mineral N fertilizer (MIN). During the residual years, only the MIN treatment was carried out every year according to crop needs. Grain yield and total plant N and P accumulation were evaluated each year, whereas metal accumulation was determined on a 3 yr cycle. The residual effects of PB applications increased crop yields in some years, but the effects were generally lower than with MIN. Plant N recovery in the first three residual years was half of that recorded during years of application (15% vs. 30%), whereas P recovery was at 6%. Residual PB applications had little effect on metal accumulation in grain. Soil liming decreased zinc and cadmium concentrations in grain but increased molybdenum. This study showed that repeated applications of PB and alkaline materials continued to have a positive effect on field crops 3–5 yr after their cessation.

The depth-specific zinc (Zn) and copper (Cu) maps with high resolution (i.e., ≤10 m) are important for soil and forest management and conservation. The objective of this study was to assess the effects of easily accessible model inputs, i.e., existing coarse-resolution parent material, pH, and soil texture maps with 1:1 800 000–2 800 000 scale and nine digital elevation model (DEM)-generated terrain attributes with 10 m resolution, on modelling Zn and Cu distributions of forest soil over a large area (e.g., thousands of km²). A total of 511 artificial neural network (ANN) models for each depth (20 cm increments to 100 cm) were built and evaluated by a 10-fold cross-validation with 385 soil profiles from the Yunfu forest, South China, about 4915 km² areas. The results indicated that the optimal models for five depths engaged five to seven DEM-generated attributes together with three coarse-resolution soil attributes as inputs, respectively, and accuracies for estimating Zn and Cu varied with R² of 0.76–0.85 and relative overall accuracy ±10% of 74%–86%. The produced maps showed that DEM-generated sediment delivery ratio, topographic position index (TPI), and aspect were the most important attributes for predicting Cu, but flow length, TPI, and slope were for Zn, which heavily affected Zn and Cu distributions in detail. Boundaries of three coarse-resolution maps were still visible in the generated maps indicated that the maps affected the distributions of Zn and Cu in large scales. Thus, the modelling method, i.e., developing ANN models with k-fold cross-validation, can be used to map high-resolution Zn and Cu over a large area.

Little research has compared land application of stockpiled (SM) or composted (CM) beef feedlot manure with straw (ST) or wood-chip (WD) bedding on loss of reactive phosphorus (RP) in runoff. We conducted a 6 yr (2013–2018) rainfall simulation-runoff study and utilized surface (0–5 cm) soil collected from a long-term (since 1998) field experiment on a clay loam soil in southern Alberta, Canada. The treatments consisted of SM or CM with ST or WD bedding applied at 13, 39, and 77 Mg·ha⁻¹ (dry weight), as well as an unamended control and mineral fertilizer treatment. Surface soil was collected from all treatments after 15–17 (C15, C16, C17; 2013–2015) continual annual applications, and then 1–3 yr (L1–L3, 2016–2018) into the legacy phase after manure applications were first discontinued in 2015. The soil was packed into runoff trays, and flow-weighted mean concentrations (FWMCs) and mass loads of RP₅ (<5 μm filter) in runoff water were determined during rainfall simulations. Our findings generally supported our null hypothesis of similar RP₅ losses for manure type (CM = SM) and bedding (ST = WD) for most years. Successively higher application rates increased RP₅ loss by 32%–121%. Termination of long-term applications dramatically reduced FWMCs by 58%–77% and mass loss by 56%–65% from the C17 to L3 years. This suggests an accumulation of soil P during continuous phase and depletion during legacy phase; therefore, lower application rates or termination of applications may reduce RP₅ loss in runoff.

Applying abundant manure to soils can accelerate nitrogen (N) transformations and nitrous oxide (N₂O) emissions. We conducted a laboratory incubation to examine the turnover of labile N in manured soils. Soils were collected from agricultural fields that had recently received spring-injected liquid dairy manure with or without admixing nitrification inhibitors. Bands and interbands of the manure plots were incubated separately. Time courses of ammonium (NH₄⁺) and nitrate (NO₃⁻) were used to derive and contrast zero-, first-, and second-order kinetics models. We found that nitrification rates were consistently better represented by first-order kinetics (k₁). Furthermore, across all evaluated soils, the dependency of nitrification rate (k₁ of NH₄⁺) on initial NH₄⁺ concentration was modelled by Michaelis–Menten kinetics reasonably well, with an affinity (K_m) of 63 mg N·kg⁻¹ soil (R² = 0.82). Compared with the manure interbands, the initially NH₄-enriched bands had a much faster nitrification rate, with half-life for NH₄⁺ of only 4 d and rapid k₁ (0.186 versus 0.011 d⁻¹). Soil N substrate and k₁ exerted control on N₂O production. Nitrous oxide production increased linearly with both measured NH₄⁺ intensity (R² = 0.47) and modelled k₁–NH₄⁺ (R² = 0.48). Conversely, N₂O production increased non-linearly with NO₃⁻ intensity (R² = 0.68), where high NO₃⁻ caused a saturation plateau with a threshold of 96 mg N·kg⁻¹·d⁻¹ — beyond which no additional N₂O was produced. During peak N transformations, measured N₂O-N flux was 1.4% ± 0.3% of the inorganic N undergoing nitrification. Heavily manured soils exhibited augmented N turnover that increased N₂O fluxes, but inhibitors reduced these emissions by half.

Long-term cattle manure applications build up nutrient pools and can lead to trace element enrichments in soils. The objectives of this study were to evaluate copper (Cu) and zinc (Zn) loadings in the soil during continuous annual cattle manure applications and determine the time required for soil to return to its pre-manure available Cu and Zn levels after manure is discontinued. The manure application rates were 0, 30, 60, and 90 Mg·ha⁻¹ for rainfed and 0, 60, 120, and 180 Mg·ha⁻¹ (wet weight) for irrigated plots. Although manure was applied for 45 yr in some plots, applications were terminated in one subset of treatments after 14 yr and in another subset after 30 yr to study legacy effects after 31 and 15 yr, respectively. Soil samples were collected in the fall of 2003, 2008, 2013, and 2018 and analyzed for available Cu and Zn. Crops were grown in all years continuously with Cu and Zn concentrations measured in both silage and grains harvested. The regression model developed using data collected suggests long legacy effects with recovery time to pre-manure levels ranging from 10 to 20 yr for Cu and 23 to 41 yr for Zn at irrigated and 10–24 for Cu and 21–32 yr for Zn under rainfed, respectively. Long-term applications of cattle manure could lead to accumulation of Cu and Zn, creating long-lasting legacy effects in soils with the increased environmental risk of leaching to groundwater.

Water availability and pH are important factors to consider to determine the suitability of a material for use as a growing medium. Unfortunately, most horticultural substrates are characterized by their water repellency. This is the case with peat moss which is hydrophobic and acidic. Synthetic surfactants are required to improve its wettability. In this study, a combination of phosphorylated wood pulp fibers (FLP) and zeolite is proposed as a substitute to surfactants to increase the wettability of peat moss in the presence of lime, an additive generally used as fertilizer or pH regulator. Results show that lime reduces the water retention capacity of FLP. However, the addition of 15% zeolite to the peat moss/FLP system increases the pH and water retention of the substrate. The negative effect of the presence of 1 wt. % lime on the water retention of the peat moss/FLP mixture was corrected by zeolite addition. Optimal conditions were obtained at 10% zeolite for the two types of lime tested with favorable pH and water retention capacity values. Zeolite was shown to have a higher affinity than FLP for calcium ions preventing the detrimental interaction between FLP and calcium ions.

There is an urgent need for brackish groundwater-based irrigation methods to be developed for saline soils that are effective, economically advantageous, and environmentally friendly. The use of both ionized brackish water and polyacrylamide (PAM) might provide such a method. The long-term use of brackish water irrigation can lead to the secondary salinization of soil and, as a consequence, restrict the development of the agricultural economy. Here, we conducted one-dimensional vertical infiltration experiments to examine the effects of ionized brackish water and PAM on soil infiltration characteristics. The result indicated that the water retention of soil first increased and then decreased with the increased in PAM application rates. The maximum water retention of soil was obtained in PAM application of 0.04% for ionized brackish water treatment. Soil water storage for the 0.04% PAM application under ionized brackish water irrigation was the highest and 5.1% higher compared with non-ionized brackish water at a PAM application rate of 0.04%. The ionized brackish water treatment at a PAM application rate of 0.04% improved the desalinization efficiency by 2.3% compared with non-ionized brackish water treatment. Thus, ionized treatment and PAM application are effective for improving the characteristics of soil water and salt transport and permit the safe use of brackish groundwater for irrigation.

Soil organic carbon contents and depths of Ap horizons (i.e., cultivated topsoil) from Ontario soil survey reports were reviewed, analyzed, and compared from 1950 to 2019. Organic carbon concentrations have declined from 2.85% to 2.34% in Ap horizons, whereas depths have increased by 40%. Considering the entire Ap horizon depth, we show that soil carbon stocks (kg C·ha⁻¹) may be constant or increasing. Losses of organic carbon due to cultivation should not be discounted; however, dilution of organic carbon within a deeper plow layer may contribute significantly to observed decreases in organic carbon concentrations in topsoil.

Increasing the functional diversity of cover crop polycultures has potential to modify nutrient cycling. Aboveground tissue from rye (Secale cereale), vetch (Vicia villosa subsp. dasycarpa), and chicory (Cichorium intybus) was arranged in litterbags, and rates of nutrient supply were measured. A control, monocultures of each species, a biculture of rye:vetch, and a polyculture of rye:vetch:chicory were compared. Increasing functional diversity through reducing the quantity of rye tissue by 30% to include 10% chicory and 20% vetch increased the total amount of nitrogen released by 257%.

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.

Microorganisms mediate soil organic carbon (SOC) turnover, and microbial residues contribute a significant portion to SOC storage in temperate agroecosystems. However, little is known about the direct effect of temperature on microbial residues associated with SOC sequestration/decomposition. We assessed microbial residue dynamics in a 28 d incubation conducted at four temperatures (5, 15, 25, and 35 °C). Microbial residues did not change with time from 5 to 25 °C. However, at 35 °C, fungal residues decomposed significantly with time, and the decomposition rate was higher than SOC. Considering the important contribution of fungal residues to stable-C pool, our findings indicated warming may be detrimental to C stability in this temperate soil.