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

Abstract

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 [ϴ] at 0, −33, and −100 kPa soil water pressures) and thermal properties (thermal conductivity [λ], 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 ϴ at 0, − 33, and − 100 kPa soil water pressures by 23%, 25%, and 28%, respectively relative to NC management. Thus, λ 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 λ at saturation, ϴ played the greatest role in λ at other soil water pressures. Expectedly, ϴ 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.