Precision agriculture (PA) involves the management of agricultural fields including spatial information of soil properties derived from apparent electrical conductivity (EC_a) measurements. While this approach is gaining much attention in agricultural management, farmed podzolic soils are under-represented in the relevant literature. This study: (i) established the relationship between EC_a and soil moisture content (SMC) measured using time domain reflectometry (TDR); and (ii) evaluated the estimated SMC with EC_a measurements obtained with two electromagnetic induction (EMI) sensors, i.e., multi-coil and multi-frequency, using TDR measured SMC. Measurements were taken on several plots at Pynn’s Brook Research Station, Pasadena, Newfoundland, Canada. The means of EC_a measurements were calculated for the same sampling location in each plot. The linear regression models generated for SMC using the CMD-MINIEXPLORER were statistically significant with the highest R² of 0.79 and the lowest RMSE (root mean square error) of 0.015 m³ m⁻³ but were not significant for GEM-2 with the lowest R² of 0.17 and RMSE of 0.045 m³ m⁻³; this was due to the difference in the depth of investigation between the two EMI sensors. The validation of the SMC regression models for the two EMI sensors produced the highest R² = 0.54 with the lowest RMSE prediction = 0.031 m³ m⁻³ given by CMD-MINIEXPLORER. The result demonstrated that the CMD-MINIEXPLORER based measurements better predicted shallow SMC, while deeper SMC was better predicted by GEM-2 measurements. In addition, the EC_a measurements obtained through either multi-coil or multi-frequency sensors have the potential to be successfully employed for SMC mapping at the field scale.

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.

In temperate cold regions, the gradual resurgence of soil microbial activity during spring freeze-thaw events is frequently associated with greenhouse gas emissions. Enhanced greenhouse gas fluxes during spring freeze-thaw are related to the mineralization of bioavailable substrates, which may be elevated when soil is amended with organic residues (e.g., biobased residues such as compost, digestate, biosolids). The objective of this study was to determine the impact of biobased residues, compared to urea fertilizer, on greenhouse gas emissions during spring freeze-thaw events. The field treatments included urea (170 kg N ha⁻¹ y⁻¹), composted food waste (240 kg N ha⁻¹ y⁻¹), hydrolyzed biosolids (215 kg N ha⁻¹ y⁻¹), and anaerobic digestate (231 kg N ha⁻¹ y⁻¹). Headspace gases were sampled from a closed static chamber in each replicate plot (n = 4) and categorized with three transient spring freeze-thaw phases (waterlogged, wet, and dry). Among the treatments, nitrous oxide (N₂O) flux was significantly different (p < 0.05) where compost had the highest emission and digestate lowest while carbon dioxide (CO₂) and methane (CH₄) fluxes were not significantly different (p > 0.05). The greenhouse gas fluxes were significantly different among the freeze-thaw events (p < 0.05) likely due to intense microbial activity and anaerobic conditions. The CO₂ and CH₄ emissions were related to N₂O emission (p < 0.05), and soil temperature strongly correlated with CO₂ fluxes. This suggested that soil warming driven by ambient conditions as well as the type and quantity of carbon input influenced soil microbial activity, leading to greenhouse gases production. Therefore, soil amended with biobased residues may either increase or reduce greenhouse gas fluxes during spring freeze-thaw events depending on the source and production method of the organic material.

Sustainable valorization of pulp and paper mill biosolids (PPMB) can improve soil fertility and reduce reliance on synthetic fertilizers in cold-region agriculture. This two-year field study assessed PPMB as a soil amendment for canola ( Brassica napus L.) and wheat ( Triticum aestivum L. ) in Northern Manitoba, Canada. Six treatments; control, urea, mixed PPMB, and three PPMB–urea combinations; were tested in a randomized complete block design. PPMB application reduced soil bulk density by 15-20% compared to urea and increased soil organic carbon by up to 21% under mixed PPMB. Microbial respiration responses were variable, and yield outcomes for both crops were comparable to or higher than urea. Redundancy analysis showed positive links between improved soil attributes and yield. The findings indicated that PPMB can sustain crop production and improve soil health in cold climates, supporting circular bioeconomy applications in northern agriculture.