The challenges associated with the global phosphorus (P) cycle are complex and multifaceted, from geological resource limitation, to P deficiency on arable farmland, to environmental contamination via excess P fertilization. Although no single solution can address all of the challenges associated with the P cycle, the principle of circularity provides a framework toward a more sustainable and food-secure P system. Phosphorus deficiency on farmland is widespread, particularly on organically managed farms due to negative P balances in low-input cropping systems. Recycled nutrient sources divert food and human wastes back onto farmland; they have the potential to ameliorate both the global-scale issues of phosphate rock depletion and environmental contamination and the farm-scale issue of P deficiency, particularly for organic farms. For recycled nutrients to act as viable alternatives to conventional nutrient sources, their ability to supply P and improve yields must be demonstrated. This paper provides an introduction to the importance of recycled fertilizer sources in the global P cycle, and the key role they can play on organic farmland in Canada.

The general incidence of copper (Cu), zinc (Zn), and boron (B) deficiencies in soils of the Canadian prairies may be related to identifiable, highly variable, inherent soil attributes. The objective of this study was to investigate the variability of selected properties and their relationship with the bioavailability, forms, and distribution of Cu, Zn, and B in a range of prairie soils. The nature of these micronutrient distributions were evaluated by measuring extractable concentrations, supply rates, and by separation into various chemical pools through sequential extraction and spectroscopic speciation analyses. Soil pH was found to be the least variable property [coefficient of variation (CV) < 13%], whereas carbonate content was the most variable (CV > 130%). The Cu and B availability showed strong negative correlation with the sand content in all soils. Path coefficient results indicated that organic carbon had the highest positive direct effect on availability and supply of Cu and B in Grey soils. Extractable Zn was positively correlated with organic carbon content of Brown and Dark Brown soils. Overall, high sand content and low organic matter were identified as important soil properties contributing to the deficiency of Cu, Zn, and B. The major proportion of Cu, Zn, and B was found in the recalcitrant residual fraction (59%–88%), with the smallest proportions in labile soluble, exchangeable forms (2%–8%). The X-ray absorption near edge structure revealed that Cu and Zn associated with carbonate minerals were dominant forms of these micronutrients present in all soils. Chemisorption is likely a major process regulating the bioavailability of Cu and Zn in prairie soils.

Long winters in the Red River Valley (RRV) of eastern North Dakota and western Minnesota result in short growing seasons for corn (Zea mays L.)–soybean (Glycine max L. Merr.) systems. Historically, producers implement aggressive tillage to warm the soil, which has caused hesitation when considering reduced tillage systems. The association between soil warming–drying and crop yields via research at farmer-operated, production-scale systems practicing reduced tillage is lacking. A two-year study was conducted at three producer-operated, corn–soybean fields in the RRV with five soil series ranging from sandy loams to silty clays. Soil temperature (T), soil volumetric water content (θ), and crop yields were measured to evaluate the effects of soil warming and drying and crop performance under reduced tillage practices of vertical tillage (VT), strip tillage with shanks (STS), strip tillage with coulters (STC), and chisel plow (CP). Results showed that daytime soil T and θ in the tilled strips for STC and STS (i.e., in the plant rows) were similar to CP and significantly different from VT. The ST treatments demonstrated added benefits of higher soil θ between the tilled strips (i.e., between the plant rows) during the mid-growing season when plant water needs are at their highest. However, daily averaged soil T and θ demonstrated little to no significant differences among the tillage treatments. Moreover, crop yields were inconsistent with soil T and θ, indicating weak to no practical association in these on-farm settings.

Water erosion threatens large areas around the world. “Donga” is one of the witnesses of gully erosion in northern Benin, which induces serious threats to the natural habitats. This study was conducted to evaluate soil moisture content in different donga types (“microdongas”, “mesodongas”, and “megadongas”) and its variation at different topographic levels. The thermogravimetric soil moisture measurement technique was used for moisture estimation on saturated and unsaturated soil. Data were analyzed through analysis of variance test and t test with SAS software. The results showed that soil moisture content varied according to donga types. On unsaturated soil, higher difference (2.75%, p = 0.0328) was obtained in mesodongas at the middle followed by megadongas at the middle (2.6%, p = 0.034). On saturated soil, higher difference was obtained in mesodongas at the upstream (6.51%, p < 0.0001) at downslope (4.55%, p = 0.0032) and in the middle (4.32%, p = 0.0328) followed by microdongas at the upstream (2.25%, p < 0.0001). The findings in this paper should be useful to researchers looking for soil moisture information in subarid and subhumid zone at different topographic levels to develop afforestation strategies based on species that can make the best use of soil water.

There has been a continued adaption and application of soil health tests across all regions of the globe; however, there are challenges related to the interpretation of the results of soil health tests developed in one region but applied elsewhere. To determine the factors that are the most important for interpreting soil health tests in Nova Scotia, a soil health database was constructed using soil samples from diverse cropping systems and soil orders in the region. The Comprehensive Assessment of Soil Health, developed at Cornell University in New York, was adapted and combined with other soil health measures. Principal component analysis (PCA), analysis of variance, and a correlation analysis were applied to the dataset to determine if management (i.e., cropping system) or pedogenesis (i.e., soil order) was more important as a driver of soil health test results. It was determined that cropping systems explained more variance in the dataset than soil order. Although total carbon explained the most variation in the PCA, it was highly correlated to other measures of carbon such as permanganate oxidizable carbon and respiration that may be more responsive to management changes. In addition, autoclaved-citrate extractable protein, a test for nitrogen mineralization, was more related to measures of soil carbon than other measures of soil nitrogen availability. The findings of this study provide a foundation for interpreting soil health testing results for this region and will help indicate which cropping systems and soil management practices have the greatest potential for improving soil health.

Termination by tillage is one strategy used for regenerating pasture stands. Yet, research gaps exist on how tillage affects carbon (C) and nitrogen (N) forms and amounts in western Canadian soils. We measured total soil organic C (SOC), dissolved organic C (DOC), total dissolved N (TDN), light fraction organic C (LFOC) and light fraction organic N (LFON), microbial biomass C (MBC) and microbial biomass N (MBN), and inorganic N as indicators of soil organic matter (SOM) dynamics. After tillage termination in fall 2018, we sampled soils (0–10 cm; 0–15 cm) under three legume species (alfalfa, cicer milkvetch, and sainfoin) three times (spring, summer, and fall of 2019) across three landscape positions. Legume species did not affect the measured parameters. Over time, tillage affected DOC, TDN, and inorganic N. Averaged across three pasture legumes and three landscape positions, tillage increased DOC 29% by summer. Fall-applied tillage led to 59% and 33% higher TDN in the succeeding summer and fall. Inorganic N increased by 14% and 40% across landscape positions and sampling after tillage. Averaged across landscape positions, MBC decreased by 31% from spring to summer and increased by 51% from summer to fall. However, MBN increased by 53% and decreased by 5% within the same period. The seasonal fluctuations in MBC and MBN reflected variations in moisture, temperature, and substrate quality. Total SOC, LFOC, and LFON increased on the upper slopes and fall sampling time. Although single intensive tillage did not affect total SOC, several tillage operations could accelerate SOM loss and reduced total C storage over time.

Chronosequence studies of soil formation and ecosystem development provide important insights into the pathways and rates of change occurring on centennial and millennial time scales. In cool or temperate humid environments, Podzols are the predominant soil type formed under coniferous forests in coarse-textured parent material and have been a major focus of chronosequence studies. This study examined the rate and mechanisms of Podzol development and related forest productivity in a sand dune chronosequence in a hypermaritime climate in coastal British Columbia (BC). The sequence spans 10 760 ± 864 yr over eight sites and is the first documented chronosequence in coastal BC to span most of the Holocene Epoch. Soil samples from each genetic horizon were analyzed for bulk density, pH and concentrations of total carbon (C), pyrophosphate- and oxalate-extractable aluminum (Al) and iron (Fe), and total elements. Within ∼3500 yr, a mature Podzol had formed, with cemented horizons (ortstein and placic) present. Organo-metallic complexation appeared to be the dominant mechanism involved in podzolization. Despite a mild, moist climate conducive to chemical weathering, all soils had similarly low values for the chemical index of alteration, suggesting that congruent dissolution of primary minerals may be occurring. Ecosystem retrogression is apparent in the latter stages of the chronosequence — a phenomenon not previously documented in coastal BC. Further research is needed to examine the interactions of nutrient limitation, soil physical barriers, and other possible drivers of ecosystem retrogression.

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.

The Weibull function is applied extensively in the life sciences and engineering but underused in agriculture. The function was consequently adapted to include parameters and metrics that increase its utility for characterizing agricultural processes. The parameters included initial and final dependent variables (Y₀ and Y_F, respectively), initial independent variable (x₀), a scale constant (k), and a shape constant (c). The primary metrics included mode, integral average, domain, skewness, and kurtosis. Nested within the Weibull function are the Mitscherlich and Rayleigh functions where c is fixed at 1 and 2, respectively. At least one of the three models provided an excellent fit to six example agricultural datasets, as evidenced by large adjusted coefficient of determination (R_A² ≥ 0.9266), small normalized mean bias error (MBE_N ≤ 1.49%), and small normalized standard error of regression (SER_N ≤ 8.08%). The Mitscherlich function provided the most probable (P_X) representation of corn (Zea mays L.) yield (P_M = 87.2%); Rayleigh was most probable for soil organic carbon depth profile (P_R = 96.4%); and Weibull was most probable for corn seedling emergence (P_W = 100%), nitrous oxide emissions (P_W = 100%), nitrogen mineralization (P_W = 58.4%), and soil water desorption (P_W = 100%). The Weibull fit to the desorption data was also equivalent to those of the well-established van Genuchten and Groenevelt–Grant desorption models. It was concluded that the adapted Weibull function has good potential for widespread and informative application to agricultural data and processes.

Mine tailings are nutrient deficient, contain no organic matter, and have high metal concentrations preventing the long-term establishment of vegetation. The use of organic amendments, including biosolids, can help the revegetation of mine tailings by adding organic matter and nutrients but can increase metals in the receiving soil. There is also uncertainty if biosolids provide a long-term benefit, or if the benefits diminish with time. To test this, a study was conducted on two tailings storage facilities — a sand, and a silt loam — for a copper mine in the southern interior of British Columbia, Canada. In 1998, biosolids were applied at rates between 50 and 250 Mg·ha⁻¹ and compared with a control and fertilizer treatment. Plots were sampled in 2000 and 2015 for total and available nutrients and metals. This study showed that 17 yr after a one-time biosolids application at different rates, the tailing storage facilities that received biosolids had higher carbon, nitrogen, phosphorus, and biomass compared with tailings that did not receive biosolids or received conventional fertilizer. Many elements such as carbon (C) did not change from 2000 to 2015 in biosolids-treated plots, indicating a long-term benefit to the tailings. Additionally, biosolids did not result in increased concentrations of metals above the national regulatory limits for agriculture. This study suggests that a one-time biosolids application can provide a long-term benefit to tailings, whereas proper application rates can reduce the risks of metal exceedances.

The impact of winter bale grazing on forage productivity and nutrient cycling was determined near Winnipeg, MB, Canada. Variable distribution of nutrients and forage yield within bale-grazed plots on a perennial grass–legume forage field was identified using an intensive grid sampling method. In bale-grazed plots, mean dry matter (DM) yield of forage decreased 68% in year 1 following bale grazing, with no difference in DM yield in year 2 following bale grazing, relative to an untreated control. Decreased yield was attributed to the large mass of waste feed and feces (21% of feed delivered) that remained at the centre of each bale-grazed plot, where each bale was placed. Concentrations of crude protein, total digestible nutrients, phosphorus (P), and potassium in forage increased in the first growing season following winter bale grazing compared with the control, particularly at the centre of each bale-grazed plot. Concentrations of residual nitrate-nitrogen and Olsen P in soil were 15 and 2.5 times greater, respectively, at the centre of the bale-grazed plots compared with untreated control plots. Dispersion of waste feed packs when bale grazing in subhumid climates on clay soils is recommended to minimize smothering and encourage rapid decomposition of waste feed and feces. Long-term studies are needed to determine the potential benefits and risks of bale grazing to forage productivity and soil nutrient status in the eastern Canadian Prairies.

The objectives of this study were to evaluate the ability of the decision support system for agrotechnology transfer (DSSAT) CERES-Maize model to simulate the response to applied nitrogen and soil water storage for maize (Zea mays L.) yields in Woodslee, Ontario. A second objective was to evaluate the CERES-Maize module for maize yield in five southern Ontario counties. The calibrated CERES-Maize module was used in 117 maize yield simulations involving combinations of 45 regional soil datasets and 35 weather datasets covering the five counties. The model evaluation showed a good agreement between the simulated and measured grain yields (i.e., index of agreement, d ≥ 0.96; modeling efficiency, EF ≥ 0.83; normalized root-mean-square error, nRMSE ≤ 15%). The model showed a large deviation using the default soil parameters from 0 to 0.4 m. A sensitivity analysis was made for three soil water parameters, and the calibrated soil parameters showed moderate to good agreements for total soil water storage in the 0–1.1 m soil profile. The model resulted in moderate to good agreement between the simulated and the measured above-ground biomass across growing seasons. There were significant yield differences across the soil types. Drought periods in August 2010 resulted in lower yields in 2010 compared with 2011 and 2012. The simulated average maize yields at each county matched well with the measured data for 2010–2012 except for lower estimated yields in Lambton county in 2010. We concluded that DSSAT CERES-Maize can adequately simulate regional maize yields using the CERES-Maize module calibrated to regional soil and daily weather databases.

Soil structure plays a critical role in agroecosystems because it controls soil air and water capacity, nutrient availability, and crop root growth. A field experiment was conducted to evaluate the effect of bentonite on soil relative water content, soil cone penetration resistance, soil bulk density, aggregate size distribution, and millet crop yield components in a semi-arid region in northern China from 2011 to 2015. Treatments consisted of six bentonite rates (0, 6, 12, 18, 24, and 30 Mg·ha⁻¹) applied only in the initial year. Addition of bentonite significantly increased soil relative water throughout the profile (0–60 cm) and aggregates in 0.25–2 mm class in 0–40 cm depth; it significantly decreased soil bulk density, soil cone penetration resistance, and aggregates in 0.053–0.25 mm class in the 0–40 cm depth. All of the bentonite treatments significantly increased 1000-kernel weight and panicle number up to 16% and 33%, respectively, but did not affect kernels per spike. Treatment with 24 Mg·ha⁻¹ bentonite achieved the greatest effect on all the soil physical parameters and crop yield components averaged over all years; the highest application rate (30 Mg·ha⁻¹) had an increasing effect over time. This study indicates that application of bentonite improves soil health in sandy-loam soil in a semi-arid region, and thus it would help promote sustainable agriculture development in regions with similar soil and climate.

Although it is well established that soil temperature has substantial effects on the agri-environmental performance of crop production, little is known of soil temperatures under living cover crops. Consequently, soil temperatures under a crimson clover and white clover mix, hairy vetch, and red clover were measured for a cool, humid Brookston clay loam under a corn–soybean–winter wheat/cover crop rotation. Measurements were collected from August (after cover crop seeding) to the following May (before cover crop termination) at 15, 30, 45, and 60 cm depths during 2018–2019 and 2019–2020. Average soil temperatures (August–May) were not affected by cover crop species at any depth, or by air temperature at 60 cm depth. During winter, soil temperatures at 15, 30, and 45 cm depths were greater under cover crops than under a no cover crop control (CK), with maximum increase occurring at 15 cm on 31 January 2019 (2.5–5.7 °C) and on 23 January 2020 (0.8–1.9 °C). In spring, soil temperatures under standing cover crops were cooler than the CK by 0.1–3.0 °C at 15 cm depth, by 0–2.4 °C at the 30 and 45 cm depths, and by 0–1.8 °C at 60 cm depth. In addition, springtime soil temperature at 15 cm depth decreased by about 0.24 °C for every 1 Mg·ha⁻¹ increase in live cover crop biomass. Relative to bare soil, cover crops increased near-surface soil temperature during winter but decreased near-surface soil temperature during spring. These temperature changes may have both positive and negative effects on the agri-environmental performance of crop production.