A sequence of Brown, Dark Brown and Black Chernozems spanning a 600 m elevation gradient in a semiarid bunchgrass ecosystem (Lac du Bois Grassland) near Kamloops, British Columbia was first described in 1961. More soil organic carbon (SOC) at higher elevations along the sequence was attributed to increasing effective precipitation with increasing elevation. Since the 1961 study, plant community composition has shifted toward the desired climax community due to improved livestock management instituted in the 1970s; however, changes in soil carbon stocks remain unknown. The objective of this study was to quantify SOC and soil inorganic carbon (SIC) stocks using the same site selection criteria as used in 1961. SOC stocks (kg m⁻² ± SD; 0–60 cm) were similar for Brown (5.73 ± 1.7) and Dark Brown Chernozems (5.87 ± 0.76) but increased sharply (10.11 ± 2.5) for the higher elevation Black Chernozems. SIC increased with depth in all three soil zones, representing 33%–50% of total C from the 30–60 cm soil depth. To evaluate changes in SOC (0–20 cm) from the 1961 measurements, three different approaches for calculating SOC stocks were used based on the inclusion or exclusion of coarse fragments. Results varied across the three soil zones from no change to a 20% increase in the Brown, an increase of 7% to a reduction of 26% in the Dark Brown, and a decrease of 12% to 35% in the Black soil zone. Information about soil coarse fragments and the distribution of SOC and SIC stocks within the soil profile is crucial for accurate comparisons across studies or resampling events.

Soil degradation has been of great concern for New Brunswick's potato farmers, especially on sloped land and shallow soils. In this study, we evaluated the initial response of labile soil carbon (C) fractions (permanganate oxidizable C (POXC) and particulate organic C (POC)) and aggregate stability to two integrated best management practices (BMPIs) composed of the following individual practices: diversion terraces (DT), grassed waterways (GW), and contour tillage (CT) (i.e., DTGW) and DT, GW, CT, and tile drainage (TD) (i.e., DTGW + TD), relative to CT that served as a control. The more water was regulated in the field, the greater the increase in labile C; where DTGW and DTGW + TD gained 19.8% and 50.6% of POXC, respectively, while CT lost 11.2% of POXC. There was an increase in mineral associated organic matter C in the terraced BMPIs, despite the high amount of tillage events that took place during potato cultivation. Two BMPIs had no effect on aggregate stability, most likely due to the short duration of this initial monitoring study that spanned just over two growing seasons. Even though there were no improvements in soil structure, our findings showed that some stabilization of soil C is possible even during the initial two seasons following BMPI implementation.

Soil water, salt, and nutrient variability are essential factors that impact crop productivity in agriculture systems. However, effective management of small farms requires access to fine-scale data on soil water, salt, and nutrients. Large-scale assessments of spatial variability using classical statistics and geostatistical methods can help identify nutrient-deficient zones. In Xinjiang, China, inadequate water and nutrient management has resulted in low crop productivity in agriculture systems. To address this issue, this study evaluated the mechanical composition, bulk density, and contents of water, salt, ammonium nitrogen (), nitrate nitrogen (), and available phosphorus (A-P) in soil at the farm level in the Xinjiang region. Results showed low variability in soil bulk density, medium variability in soil water content, mechanical composition, , and A-P, and high variability in soil salt content and . Mechanical composition and A-P showed a small range of variation across different soil depths, while soil water content and in the surface layer varied significantly more than in other soil layers. variability increased with soil depth. Soil properties showed minimal differences over time. Multi-factor deficiencies, particularly in nitrogen, were observed throughout the study area. The generated maps offer a useful tool for farm managers and policymakers. In summary, this study highlights the significance of evaluating the spatial variability of soil properties for identifying zones deficient in water and nutrients, as well as those with salt accumulation. This information can be utilized to develop effective strategies for site-specific nutrient management.

Potato (Solanum tuberosum L.) crops are often cultivated in coarse-textured soils with low soil organic matter and high nitrate leaching risk. Incorporating shrub willow chips into soil could enhance soil properties, while temporally immobilizing N and thus reducing N leaching. We performed a laboratory incubation study and a field experiment to evaluate the effects of shrub willow chips applied at increasing rates in the fall after the potato harvest on C, N and P cycling, soil pH and moisture, and on barley (Hordeum vulgare L.) yield in the following year. In comparison with the control, willow chip incorporation at the rates of 40 and 60 Mg ha⁻¹ increased total C content, but it did not affect the activity of C cycling enzymes. Willow chip addition at these rates also induced nitrate immobilization and reduced barley grain yield and total N uptake, but increased the activity of N cycling enzymes (β-1,4-N-acetylglucosaminidase and leucine aminopeptidase). Mehlich-3 extractable P content and phosphomonoesterase activity were not affected by willow chip addition. Our results suggest that shrub willow chips increased total organic C and immobilized N following their incorporation and can thus mitigate nitrate leaching after the potato harvest. The N immobilization was short lived and was not observed over second winter. We recommend to seed a forage legume in the spring following shrub willow chip incorporation. Willow chip incorporation is an effective means of increasing soil organic carbon.

Identifying and characterizing the spatial patterns in soil moisture variability under different land use conditions is crucial for agriculture, forestry, and civil and environmental engineering. Yet employing multifrequency (MF) electromagnetic induction (EMI) techniques to carry out this task is under-represented in boreal podzolic soils. This study (i) compared four frequencies (∼2.8–80 kHz) for shallow mapping of soil moisture measured with a time–domain reflectometry at 0–20 cm soil depth under three different land use conditions (agricultural land, field road, and a recently cleared natural forest), (ii) developed a relationship between apparent electrical conductivity (EC_a) measured using multifrequency EMI (GEM-2) and soil moisture, and (iii) assessed the effectiveness of EC_a as an auxiliary variable in predicting soil moisture variations under different land use conditions. The means of EC_a measurements were calculated for the exact sampling location (ground truth data) in each land use condition at a research site, Pasadena, NL, Canada. Soil moisture–EC_a linear regression models for the three land use conditions were only statistically significant for 38.3 kHz frequency and were further analyzed. Further statistical analysis revealed that EC_a was primarily controlled by soil moisture for the three land use conditions, with the natural forest possessing the highest mean EC_a and soil moisture. Geostatistical analysis revealed that cokriging EC_a with less densely collected soil moisture improved the characterization accuracy of soil moisture variability across the different land use conditions. These results reveal the effectiveness of the georeferenced MF–EMI technique to rapidly assess intrafield soil moisture variability under different land uses.

Soil salinization has produced severe consequences on global agricultural production and ecological environment. Based on the features of saline soils in China, through mixed NaCl, NaHCO₃, Na₂SO₄, and Na₂CO₃ at varying ratios to simulate the salinity–alkalinity stress and conducted a controlled pot experiment using De Wit replacement method. The effects of salinity–alkalinity stress on the growth of Aegilops tauschii and its competition with wheat were explored to provide a reference for the study of invasion mechanism of A. tauschii. The result showed that, the salinity–alkalinity stress inhibited the growth and development of both the species, which was reflected in plant height, leaf area and total biomass indicators. Secondly, the tolerance of both plant species to salinity–alkalinity stress was improved by increasing the superoxide dismutase (SOD) activity and the proline content. However, as the salinity–alkalinity stress was exacerbated, the relative conductivity and thiobarbituric acid (TBARS) content increased significantly in both the species. As suggested by the level of increase in SOD activity, proline content, relative conductivity, and TBARS content, A. tauschii was more tolerant to the salinity–alkalinity stress than wheat. Finally, it can be seen from the value of the competition balance index, A. tauschii was still more competitive than wheat even under salinity–alkalinity stress. In summary, A. tauschii was more tolerant of the salinity–alkalinity stress than wheat through the favorable adjustment of morphology, biomass allocation pattern, and physiological features, which is expected to increase its invasion damage to wheat.

The undulating topography of Prairie Pothole Region of North America creates spatial and temporal variability in soil moisture and nutrient levels, affecting microbial community processes and greenhouse gas emissions. By identifying differences in soil bacterial and archaeal community composition and the abundance of nitrogen cycling genes in permanent cover versus annual crop land over two growing seasons (2017 and 2018), we were able to assess the effects of topography and land use on the functional capacity of the soil microbiome. Permanent grassland cover was associated with higher bacterial diversity in upland positions and lower diversity in low-lying depressions. Bacterial community composition was also significantly different between cultivated and permanent cover at all points along the topographic slope, with the largest effects seen in the footslope and backslope positions. Compared to permanent cover, soil from annual cropland had consistently more abundant nitrifiers, including Nitrospira in the toeslope and backslope, and Nitrososphaeraceae in the shoulder and knoll samples while soils from permanent cover had a greater abundance of several Alphaproteobacteria from Rhodospirillales and Hyphomicrobiaceae across multiple upland positions. Upland soils from annual cropland also had consistently higher abundance of both bacterial and archaeal ammonia oxidizing (amoA) genes and a higher ratio of nirK:nirS genes compared to those from permanent cover. These differences in microbial community composition were associated with higher N₂O and CO₂ emissions in upland soils in annual cropland; however, there were no differences in GHG emissions between the two systems in low-lying positions.

Biobased residues derived from organic urban waste materials can be processed to produce soil amendments that enhance soil fertility and carbon sequestration. However, the extent of carbon sequestration by biobased residues depends on the interaction between their physicochemical properties, climate, and agroecosystem management practices. Our objective was to predict how different biobased residues (compost, anaerobic digestate, or biosolids), compared to nitrogen fertilizer, affect soil organic carbon stocks under continuous cropping and crop rotation in Ontario, Canada, using the Century model. The Century model was calibrated and validated with data, from a three-year field study located in Elora, Ontario, Canada, that was used to predict long-term changes in soil organic carbon. Our results showed that after 150 years, soil amended with compost and biosolids increased soil organic carbon stocks significantly (p < 0.05) compared to anaerobic digestate and nitrogen fertilizer. Soil organic carbon stocks were 1%–27% greater with crop rotation compared to continuous cropping. Model performance indicated a strong correlation between measured and simulated soil organic carbon stocks (R² = 0.26–0.82; RMSD = 432–727 g m⁻²). Our findings suggested that compost had the greatest soil carbon sequestration potential of the tested soil amendments, and this difference was due to the quantity and quality of carbon input.

Commonly used soil water retention, θ(h), and moisture capacity, C(h), functions implicitly assume that (i) the θ(h) data curve is sigmoid-shaped with an inflection and (ii) the C(h) data curve has a value of zero at soil saturation. Desorption measurements on intact soils indicate, however, that the θ(h) data curve is frequently convex-monotonic in shape with no inflection, and C(h) at saturation is often a finite negative value rather than zero. As these model-data mismatches may cause substantial error in simulation or prediction of near-saturated soil hydraulic properties and water flow, a new “Extended Schnute” θ(h)–C(h) function was proposed that can provide θ(h) curve shapes and saturated C(h) values which are consistent with θ(h) and C(h) measurements. The new function and/or its nested Schnute sub-model provided high-quality and physically realistic fits to desorption data collected from intact cores of coarse sand, loamy sand, loam, clay loam, sandy clay loam, clay, and organic clay soils; and it out-performed or equalled the three-parameter van Genuchten θ(h)–C(h) function for every data-set. The new function also provided accurate and physically realistic representations of θ(h) and C(h) data from structured soils containing macropores and strongly graded pore size distributions. It was concluded that the Extended Schnute model is capable of providing accurate and physically realistic representations for a wide range of θ(h) and C(h) data, and it was further recommended that this model be considered over other models when measurements indicate that θ(h) is convex-monotonic in shape and/or C(h) is not zero at soil saturation.

Short duration, intensive grazing management with high stocking rates may result in sufficient turn-over of nitrogen (N) to compensate for production-limiting soil-N deficiencies for grass pasture. In central Alberta a 0.5 ha block was seeded to “Fleet” meadow bromegrass (Bromus riparius Rehmann) in August 2002. Within this block, six fenced (9 m × 30 m) treatments were established in three replicates. They were (1) ungrazed—clip removal, (2) grazed—alone, (3) grazed—fertilizer, (4) grazed—fertilizer-compost, (5) grazed—hog manure, and (6) grazed—alfalfa (Medicago sativa L.) grass. Measurements were conducted over a 4-year period between 2003 and 2006 and grazing occurred at identical times as vegetative mass permitted. Biomass was harvested before and after grazing for calculation of dry matter (DM) yield and biomass consumed. Sub-samples were used for determination of N concentration and in vitro digestibility. Mean herbage N-yield for grazed treatments was 131% of ungrazed and greatest for grazed-fertilizer and grazed-fertilizer plus compost. Grazed paddocks with no added N produced similar DM yield to those with added N. Estimated nitrogen fixation contributed an annual average of 82 kg ha⁻¹ to herbage-N yield from the alfalfa-grass paddocks. Barley (Hordeum vulgare L.) silage grown after termination of the grazed pastures produced 72% more herbage DM from grazed paddocks than ungrazed, but no significant (P < 0.05) differences occurred among amendments.

The fate of sulfamethoxazole (SMX) in Prairie agroecosystems during snowmelt is not well understood. This study aims to provide the first estimates of concentrations and loads of SMX in snowmelt in a field with a history of manure application. The mean concentration of SMX throughout the snowmelt period was 0.0345 ± 0.066 µg/L. The SMX cumulative load was 3.81 ± 3.4 µg/L with a range of 1.03–12.8 µg/L. Both the concentration and load were not influenced by the method of manure application (i.e., surface applied versus sub-surface applied).