The long-term effectiveness of activated carbon (AC) in immobilizing soil-applied herbicides remains a critical concern for effective management practices for sites impacted by residual sterilants, such as bromacil and tebuthiuron. This study evaluates the sustained performance of AC amendments in reducing herbicide mobility and phytoaccessibility. Herbicide concentrations and leaching potential following AC application were assessed. Results demonstrate that AC significantly reduced detectable levels of bromacil and tebuthiuron in soil, with immobilization effects persisting after physical weathering. In many cases, AC amendment lowered phytoaccessible sterilant concentrations below limits outlined in the Alberta Tier 1 Soil Remediation Guidelines. The findings support further evaluation of AC as a remediation strategy under field conditions, with implications for practical reclamation approaches in the Canadian climate. This work advances soil amendment technologies for herbicide immobilization and reduction in herbicide bioavailability.
Vegetable cropping systems are intensively managed, yet soil health (SH) remains understudied. This study compared 50 organic and conventional vegetable farms in Quebec by documenting management practices, assessing 39 SH indicators, and identifying a minimal indicator set for routine monitoring. Soils were sampled at 0–10, 10–20 and 30–50 cm, with indicator-specific depths. Organic farms more frequently reported cover crops (100% vs. 45%), organic amendments (100% vs. 20%) and reduced tillage (56% vs. 10%), and had greater crop and cover-crop diversity. Management differences were strongest at 0–10 and 10–20 cm and less evident at 30–50 cm. Physical and chemical indicators showed few consistent differences; however, organic farms had 26% lower bulk density at 0–5 cm (0.89 vs. 1.20 g cm⁻³), 81% higher total C (3.48% vs. 1.92%) and 81% higher total N (0.29% vs. 0.16%) at 0–10 cm (all p<0.001). At 0–10 cm, microbial respiration, ACE protein and FDA hydrolytic activity were 1.67-, 2.22- and 2.62-fold higher, respectively (all p<0.001). Organic management was also associated with 27% higher fungal richness but 22% lower bacterial richness (Chao1; both p<0.001). Exploratory factor analysis identified two management-influenced SH traits: soil organic fertility and soil bacterial diversity/resource quality. The proposed minimal indicator set includes bulk density, total C and N, organic matter, microbial respiration, ACE protein, total bacterial abundance, Shannon diversity and Chao1 richness. These results identify management-sensitive SH indicators for vegetable systems and provide a basis for future validation against soil functions.
In southwestern Ontario’s humid continental climate, improving nitrogen (N) use efficiency requires balancing crop demand against overwinter leaching. This study evaluated a perennial clover strip intercropping system, using white clover (Trifolium repens L.) and subterranean clover (T. subterraneum L.), as a strategy to synchronize N supply with winter wheat (Triticum aestivum L.) demand. The research was conducted at an on-farm Living Lab (Agriculture and Agri-Food Canada) site in Dresden, Ontario, in a strip-plot arrangement comparing perennial clover strips established in 2020 with a conventional system without clover, with and without N fertilization. Soil N pools and soil health indicators were assessed from early spring through autumn to evaluate seasonal N dynamics and their impact on wheat productivity. Under zero applied N, perennial clover produced 57% more grain than conventional management, whereas the two systems did not differ where fertilizer was applied. Soluble N pools showed a significant cropping system × sampling stage interaction, and the direction of the perennial clover effect reversed over the season. While wheat was growing, NO₃⁻–N was 49% higher under perennial clover at mid-summer in fertilized plots. After harvest, autumn NO₃⁻–N was 45% to 54% lower under perennial clover at both fertilization levels. Water-extractable total N was 20% and 45% higher under clover in early spring and 23% and 32% lower in autumn in fertilized and non fertilized plots, respectively. These findings suggest that perennial clover can maintain winter wheat yield at reduced N input while lowering the residual NO₃⁻–N most vulnerable to overwinter loss, before any measurable change in bulk soil health.
Knowledge of the soil hydraulic parameters (SHPs) is crucial for many agricultural and environmental applications. However, current methods for directly measuring SHPs are time-consuming, labour-intensive, and often involve processes that disturb the soil. In this study, we combined time-lapse ground-penetrating radar (GPR) data collected during a Beerkan infiltration experiment with Hydrus-1D inverse modelling to non-destructively predict Mualem-van Genuchten (M-vG) parameters and simulate water flow dynamics at a Boreal podzolic soil in western Newfoundland, Canada. Calibration was carried out using the inverse modeling of the first infiltration experiments conducted both in the field and the laboratory, while evaluation was done through forward modeling of two additional experiments under both conditions. Resulting M-vG parameters (θr = 0.04037 cm3/cm3, θs = 0.22630 cm3/cm3, α = 0.04252 cm−1, n = 1.66660, Ks = 0.00259 cm/s) obtained from the inverse modeling of the GPR data in the field were comparable with estimates from Rosetta neural network prediction for our soil and other conventional methods. The evaluation results revealed a good agreement between the simulated and measured soil water content with a root mean square error of 0.0199–0.0365 cm3/cm3 and Nash-Sutcliffe modeling efficiency of 0.2955‒0.8273. The approach presented in this study offers a promising non-invasive method for large-scale characterization of soil water dynamics and SHPs in Boreal podzolic soils, yet further validation across diverse conditions and adoption of more advanced simulation models, such as Hydrus 2D/3D, could improve the accuracy of water flow simulation and provide spatial visualization of flow paths.
Environmental change is intensifying abiotic stresses such as heat, salinity, drought, and nutrient imbalance, threatening agricultural sustainability and destabilizing soil ecosystems, whose resilience is essential for maintaining carbon dynamics, nutrient cycling, and plant stress responses. Engineering the soil’s microbiome might be a solution to these problems. However, current microbiome-engineering approaches are often reductionist, relying on individual microbial strains or short-term interventions that do not adequately account for soil heterogeneity, resident microbial communities, plant genotype, and environmental variability. In this review, we reframe soil microbiome engineering as a dynamic and adaptive process in which interventions are designed according to the functional limitations of specific soil-plant systems. We propose a Soil-Plant-Microbiome Resilience Framework that integrates soil physicochemical properties, microbial community dynamics, plant physiological responses, management practices, and environmental stressors through feedback-regulated interactions. We further translate this framework into a practical engineering pathway based on site diagnosis, selection of microbial or habitat-based interventions, field deployment, monitoring, and adaptive management. Particular, attention is given to the context-dependent performance of bacterial and fungal inoculants and to property-based selection of biochar rather than its use as a generic amendment. By linking ecological mechanisms with site-specific management, this framework provides a basis for developing more reliable, field-relevant, and resilient soil microbiome interventions under environmental change.
