Soil thermal properties: influence of no-till cover crops

Soil thermal properties, which determine heat transport, can influence soil health parameters and crop productivity. The objective of this study was to evaluate the 2-year effects of no-till cover crops (CCs) and no-till no cover crop (NC) on soil thermal properties (thermal conductivity (λ), volumetric heat capacity ( C V ), and thermal diffusivity ( D)). Two levels of CCs were used for this study: CC versus NC. The CCs included crimson clover ( Trifolium incarnatum L.), hairy vetch ( Vicia villosa Roth.), winter peas ( Lathyrus hirsutus L.), oats ( Avena sativa), winter wheat ( Triticum aestivum L.), triticale ( Triticale hexaploide Lart.), flax ( Linum usitassimum L.), and barley ( Hordeum vulgare L.). Soil samples were collected at 0–10, 10–20, and 20–30 cm depths and their λ, C V , and D were measured in the laboratory. Additionally, soil organic carbon, bulk density (BD), and volumetric water content (ϴ) at saturation, −33 kPa, and −100 kPa soil water pressures were measured. Results showed that BD was 18% and 14% higher under CC compared with NC management during 2021 and 2022, respectively. Furthermore, ϴ at all measured soil water pressures was slightly higher under CC compared with NC management during both years. As a result, λ and D were significantly higher under NC compared with CC management, while C V was significantly higher under CC compared with NC management, during both years and at all measured soil water pressures. Generally, soil thermal properties were directly proportional to ϴ, suggesting that ϴ may be the most important factor influencing soil thermal properties.