Mottling and gleying remain important characteristics for the classification of soils in Canada. The development of criteria for the morphological description of these redoximorphic soil features, for soil horizon nomenclature, for the taxonomy of gleysolic and gleyed soils, as well as for soil drainage classification, began in the mid-1940s and continued for the next four decades. Despite advancements elsewhere, notably with Soil Taxonomy and the World Reference Base, there have been minimal refinements made in Canada, during the past quarter century. Various issues are identified, including the need for more succinct and clearer definitions, a revision of standards for the field characterization of redoximorphic features, as well as more consistency in the application of concepts across existing taxa and systems. A taxonomic framework to more effectively reflect redoximorphic features, such as a new “Redoximorphic Phase” is also discussed. Ultimately, it is recommended that a special committee to be established to conduct a thorough study and present recommendations.

In an agroecosystem (AES), land-use types affect soil quality. As a result, determining soil quality in various land uses is critical. This study was carried out to evaluate the soil quality index (SQI) of the different land-use types in AESs of the Choke Mountain watershed, upper Blue Nile Basin. Forty-seven soil samples were taken from cultivated land (CL), grazing land (GL), plantation forest land (PFL), and natural forest land (NFL) of the five AESs. The minimum data set (MDS) was chosen using principal component analysis. To calculate SQI, five soil quality indicators were selected as an MDS: silt, pH, cation exchange capacity, exchangeable potassium, and soil organic matter. SQIs for the overall land uses were ordered as GL > NFL > PFL > CL. Compared with NFL, the SQIs of PFL and CL were reduced by 10% and 19.7%, respectively, whereas the SQI of GL was increased by 1.8%. Among AESs of Choke, SQI of GL was higher in the midland plain, dominated by Vertisol (AES 2), followed by the midland plain with Nitosols (AES 3). SQI of CL was intermediate, and SQIs of GL, NFL, and PFL were good. AES 2 of the watershed recorded the highest total SQI value, whereas hilly and mountainous highlands (AES 5) recorded the lowest SQIs compared to other AESs. Thus, site-specific land use and management practices across the various AESs should be recommended to policymakers and farmers for a sustainable ecosystem and environment.

The waste of coal mining activities causes accumulation of hazardous elements in soil for plants. Biochar is considered an important soil remediation strategy to stabilize the heavy metals. The aim of this study was to quantify the effect of biochar sources and rate on the heavy metal stabilization in coal-contaminated soil. Biochars of three feedstocks (maize straw (MBC), rice straw (RBC), and sugarcane bagasse (SBC)) with four levels (0%, 0.5%, 1%, and 2%, i.e., 0, 10, 20, and 40 ton ha⁻¹) were applied to two types of soils (naturally contaminated soil (NCS) versus artificially contaminated soil (ACS) spiked with Cd, Cu, Cr, and Pb). Plastic pots were incubated at 30% field capacity for 90 days at 25 °C, and soil pH, electrical conductivity (EC), and heavy metals concentration were measured after 1, 4, 8, and 12 weeks. Among the biochars, RBC showed maximum immobilization of Cd, Pb, Cu, and Cr as compared with MBC and SBC. Similarly, biochar application increased heavy immobilization, being maximum at 2% (40 ton ha⁻¹) rate compared with control. The pH of both soils with biochar addition increased as compared with control. The remediation effect of biochar on heavy metal stabilization was positive over time. The higher rate (40 ton ha⁻¹) of RBC for ACS and MBC for NCS could be used effectively for heavy metal stabilization.

This study was conducted to determine the effect of arbuscular mycorrhizal fungi (AMF) symbiosis on plant growth and nutrient uptake under combined drought and salinity stresses. A pot experiment was carried out with a factorial arrangement of treatments in a completely randomized design with three replications. Experimental treatments included two plant types (Atriplex canescens and Haloxylon ammodendron) with three levels of inoculation of fungal species (Funneliformis geosporus, Funneliformis mosseae, and control), two levels of soil salinity stress (7 and 14 dS m^–1), and two levels of drought stress (50% and 80% of management allowable depletion). Vegetative parameters, as well as root N, P, and K concentrations and uptakes, mycorrhizal growth response, mycorrhizal nitrogen response, mycorrhizal phosphorus response, mycorrhizal potassium response, and root colonization were measured. The results showed that the application of AMF increased the plant growth variables such as stem diameter, root length, shoot dry weights, and shoot to root ratio as well as nitrogen and phosphorus uptakes. The application of both AMF types was effective as compared to the control. However, F. mosseae indicated better performance especially, in terms of the effect on plant growth variables. Also, F. mosseae was more effective to relieve stress (i.e., salinity and drought) than F. geosporus. There was a significant difference between plant types and H. ammodendron had better efficiency than A. canescens under drought and salinity stresses. Based on the results, planting of H. ammodendron inoculated with F. mosseae might be recommended for soil conservation in the arid environments.

For one of Canada’s most important regions of crop production—the prairies—it’s uncertain if cover crops can be successfully integrated into rotations; if so, will soil nitrogen (N) cycling be influenced to benefit main crops? To address these gaps, we compared a crop rotation with cover crops (CC) vs. without cover crops (LR) from 2018 to 2021 in Saskatoon, SK. The main crops were grown in sequence of wheat–canola–potato–pea; the cover crops included red clover, berseem clover/oat mix, fall rye, and a brassica cover. Yield and aboveground biomass were collected each year and analyzed to determine crop yield and N use efficiency (NUE). Soil N availability was monitored in various ways, that is, by assessing pre-plant soil nitrate, soil inorganic N (SIN) supply rate, and potentially mineralizable N (PMN). We found that the influence on soil N dynamics was restricted to the non-growing season where cover crops reduced SIN supply rate and nitrate content compared to the conventional practice without cover crops. Yet, rotations with vs. without cover crop did not differ in crop NUEs, yields, or in-season N dynamics. We found some evidence that diversifying rotations with cover crops may help the system to function more like perennial systems in terms of regulating N in the long run; but had limited impact during the three years studied. To ensure that cover crops are effective and functional on the prairies, innovative design approaches are needed to adapt cover crops to reach soil health goals under prairie conditions.

Forest vehicle operation causes different degrees of compaction damage to the soil, which is related to the pressure-bearing characteristics of the soil. However, scholars have not profoundly investigated the pressure-bearing factors of forest soil. In this paper, disturbed brown coniferous forest soil was collected layer by layer, dried, screened, and tested with indoor pressing-plate tests with different pressing-plate shapes and diameters (side lengths). A kind of pressure–subsidence (P–Z) curve of hard soil, which is different from those of farmland soil and homogeneous remolded soil, was obtained and drawn as the P–Z curve. The results show that in the process of pressure subsidence, the forest soil gradually changed from loose to compact. Furthermore, the change of pressure-bearing subsidence of layered soil from this forest region was characterized first by the rapid increase of soil subsidence with the increase of pressure. Then, the subsidence speed became slower with the increase of pressure; finally, subsidence speed was much less affected by the increase in pressure. According to the pressure-bearing subsidence curve of forest soil, a new subsidence model is put forward in this paper. The new model has a good prediction effect on the subsidence curve of forest soil. This paper aims to provide a theoretical basis for studying soil pressure-bearing characteristics and the development of vehicles in high-passing forest areas.

National inventory reporting of agricultural nitrous oxide (N₂O) emissions in Canada is based primarily on measurements obtained using static chambers. In regions with cold winters and an accumulated snowpack (including Canada), these measurements tend to focus on the growing season (typically May–October). However, research has shown that emissions continue throughout the non-growing season (NGS) and that these account for a significant proportion of annual emissions. In the Canadian National Inventory NGS emissions currently are assumed to be adequately captured in western Canada, while they are accounted for in eastern Canada by multiplying the growing season emissions by a correction factor of 1.4, a value that was derived based on a limited number of measurements. Here we use recent Canadian studies to validate this correction factor. We collected data from available Canadian studies that measured soil N₂O emissions from agricultural systems for the entire year and determined the proportion of these emissions that occurred during the NGS. The proportion of annual N₂O emissions that occurred during the NGS varied widely, ranging from −4% to 119% with a mean of 35.5%, compared to the previous estimate of 30%. Due to high variability, few differences were observed between means associated with climatic, soil, and management variables. To correct for NGS N₂O emissions from Canadian agricultural soils, we suggest that the current correction factor for converting growing season to total annual emissions be changed from 1.4 to 1.55 and that this be used for all agricultural soils in Canada rather than just eastern Canada.

The study aimed to investigate the effects of biochar (BC) application on hydraulic properties and nitrogen (N) transport in a podzolic soil profile. Soil samples were collected from an agricultural research field in Pasadena, Newfoundland, Canada. The following three types of leaching columns were prepared: (i) topsoil, (ii) top and E-horizon soil, and (iii) mixed soil (2:1 ratio of topsoil and E-horizon soil). Granular biochar (GBC) and powder biochar (PBC) were mixed with soils at the rate of 0%, 1% and 2% (w/w). BC’s morphological structure and pore size distribution were examined using a scanning electron microscope, and the specific surface area was assessed by the Brunauer−Emmett−Teller method. Soil physical and hydraulic properties (bulk density, porosity, field capacity (FC), permanent wilting point, plant available water (PAW)), leaching concentration of nitrate (NO₃⁻) and ammonium (NH₄⁺), and volume of leachate were measured through a total of 378 experiments under laboratory conditions. GBC and PBC showed hydrophobic and hydrophilic characteristics, respectively. With the 2% PBC amendment, porosity increased by 3%, FC by 10%, and PAW by 13% in the mixed soil and reduced NO₃⁻ leaching by 36% in top and E-horizon soil and NH₄⁺ leaching by 72% in mixed soil. On the other hand, NO₃⁻ and NH₄⁺ leaching was reduced by 26% and 33% in mixed soil when treated with 2% GBC. A 2% application rate for both BC (GBC and PBC) showed the best performance to enhance soil hydraulic properties and retain significant amounts of NO₃⁻ and NH₄⁺ in the boreal podzol.

Municipal wastewater biosolids are nutrient-rich residuals with potential as crop fertilizer, if their alkalinity does not adversely affect soil biochemical processes. This study assessed the potential soil enzyme activity after three annual applications of biosolids in a conventionally tilled field under silage corn (Zea mays L.). Biosolids were municipal wastewater sludge treated by mesophilic anaerobic digestion, lime stabilization, or composting, compared with urea fertilizer and an unfertilized control. Generally, the potential soil enzyme activity did not change with biosolids application, but the N-acetylglucosaminidase activity increased in soil amended with lime-stabilized biosolids, which also had higher soil pH and greater soil NH₄⁺ concentration.

Tile drainage is installed in agricultural fields to remove excess soil moisture to allow earlier planting of spring crops. Water moving from soil into tile drainage lines will potentially create a moist environment for earthworms. This study investigated how earthworms were distributed around tile lines, and how their abundance was affected by moisture in field crops on sandy and clayey soils. Earthworm abundance and soil moisture were similar above and between tile lines. Earthworm biomass was low in dry soils, peaked at 41 g moisture 100 g⁻¹, and declined in wetter soils, which affects the earthworm activity in agricultural fields.