No-till cover crop effects on the thermal properties of a Paleudult

Soil thermal properties play an important role in crop productivity, but the influence of a multi-species cover crops (CCs) on these properties are not well understood. This study evaluated the effects of no-till CCs (winter wheat [Triticum aestivum L.], crimson clover [Trifolium incarnatum L.], triticale [Triticale hexaploide Lart], hairy vetch [Vicia villosa], oats [Avena sativa], and cereal rye [Secale cereale L.]) on soil physical (bulk density [BD], and volumetric water content [0] at 0, -33, and -100 kPa soil water pressures) and thermal properties (thermal conductivity [lambda], volumetric heat capacity [CV], and thermal diffusivity [D]). Soil samples were collected just before CC termination at 0-10, 10-20, and 20-30 cm depths from CC and no cover crop (NC) plots during 2021 and 2022. Results showed that, after 2 years, CCs reduced BD by 17% and increased 0 at 0, - 33, and - 100 kPa soil water pressures by 23%, 25%, and 28%, respectively relative to NC management. Thus, lambda under NC was 16%, 19%, and 20% higher at 0, - 33, and - 100 kPa soil water pressures, respectively, compared with CC management. Conversely, CV was 17%, 14%, and 15% higher under CC compared with NC management at 0, - 33, and - 100 kPa soil water pressures. Regression analysis further demonstrated that while plant root was the most important factor influencing lambda at saturation, 0 played the greatest role in lambda at other soil water pressures. Expectedly, 0 was the most important factor influencing CV at all measured soil water pressures. Conclusively, no-till CCs can improve laboratory measured soil thermal properties by moderating heat transfer.