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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 [ C V ], 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, C V 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 C V at all measured soil water pressures. Conclusively, no-till CCs can improve laboratory measured soil thermal properties by moderating heat transfer. • CCs reduced BD and increased ϴ at measured soil water pressures relative to NC. • NC management significantly increased λ, while CC management improved C V. • At saturation, plant roots determined λ, while ϴ influenced λ at lower soil water pressures. • ϴ was the most important factor influencing C V at soil water pressures measured. • Multi-specie CCs can reduce extreme heat transport in a changing global climate. [ABSTRACT FROM AUTHOR]

Understanding the effects of cropping practices on soil pore characteristics is important for determining soil productivity and ecosystem services. Objectives of the study were to compare differences in computed tomography (CT) measured soil pore parameters (number of macropores, macroporosity, area of the largest pore, circularity and fractal dimension) among cover crops (CC), no-cover crops (NCC), and biofuel crops [Miscanthus (M): Miscanthus x giganteus and switchgrass (SG): Panicum virgatum ] and examine relationships between CT-measured pore parameters and soil hydraulic and thermal properties. Cover crops were Cereal rye ( Secale cereale L.), Hairy vetch ( Vicia villosa ) and Austrian winter pea ( Pisum sativum subsp. arvense ). Three replicates each of undisturbed soil cores were collected at two soil depths (0–10 and 10–20 cm) from each treatment using plexiglass cores measuring 76.2 mm diameter by 76.2 mm long. Ten scan images from each core were acquired using an X-ray CT scanner with 0.19 by 0.19 mm pixel resolution with 0.5 mm slice thickness and analyzed with Image - J . Soil under CC, NCC, M, and SG on average had 21, 14, 17, and 12 macropores on a 2500 mm 2 area across all the depths. Soil under miscanthus had significantly greater macroporosity (0.049 m 2 m − 2 ) and area for the largest pore (89.70 mm 2 ) than other treatments. The cover crop treatment had approximately 50%, 28%, and 75% greater number of macropores than NCC, M, and SG treatments. Bulk density (D b ) of soil was 13% lower in M than the NCC. Saturated hydraulic conductivity (K sat ) values were positively correlated with most CT-measured pore parameters. In contrast, D b was negatively correlated with most CT-measured pore parameters (circularity and fractal dimension were positively correlated). While the circularity values were correlated positively with D b and thermal conductivity ( λ ), the fractal dimension was correlated positively with volumetric heat capacity ( C v ). The study illustrates that M and CC treatments can improve soil pore parameters. [ABSTRACT FROM AUTHOR]