Soil Thermal Properties under Prairies, Conservation Buffers, and Corn–Soybean Land Use Systems

Abstract

Although prairies and conservation buffers are becoming popular to improve soil properties and environmental quality, very little is known about their influence on soil thermal properties. This study compared and quantified thermal conductivity (λ), thermal diffusivity (D), and volumetric heat capacity (C) of prairies (Tucker Prairie [TP] and Prairie Fork [PF]), conservation buffers (grass buffers [GB] and agroforestry buffers [AGF]), and corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation (COS) land uses in Missouri. Core and bulk soils were collected at 10‐cm depth increments. Soil thermal properties and water characteristic curves were determined at 0, −33, −100, and −300 kPa pressures. Additionally, soil organic C (SOC) and bulk density (BD) were also determined. The results showed that SOC was negatively correlated with λ and D and positively correlated with C. Significantly higher values of SOC and lower BD were observed for AGF, TP, GB, and PF than COS. Similarly, λ and D were significantly higher and C was lower under COS than the prairies and conservation buffers. The results suggest that a greater amount of SOC decreases the thermal conductance due to the insulating characteristics of SOC and acts as a barrier to heat transport. Therefore, AGF, TP, GB, and PF had lower thermal conductance to deeper soil depths, which helps to conserve more moisture as well as assist in increasing the longevity of SOC in the soil matrix. Our results imply that buffers and perennial vegetation can help reduce heat flow by increasing the thermal capacity and thereby mitigating climate change.