Soil Thermal Properties Under Prairies, Conservation Buffers and Corn/Soybean Management Systems.

Land management practices with prairies and conservation buffers are becoming popular to improve soil physical properties, erosion control and biodiversity. Very little is known how these practices influence soil thermal properties, which are very important to quantify the coupled flow of vapor and liquid in the vadose zone that has a direct impact on climate change. This study compared and quantified thermal conductivity (λ), thermal resistivity (ρ), thermal diffusivity (D) and volumetric specific heat capacity (C) of Prairies (Tucker Prairies, TP; Prairie Fork, PF), conservation buffers (grass buffers, GB; agroforestry buffers, AGF), and corn /soybean (COS) management practices in Northern and Central Missouri. Core and bulk soil samples were collected from each management practice at 10 cm depth increments. Soil water characteristic curves and soil thermal properties were determined at 0, -33, -100, and -300 kPa pressures. In addition, soil organic carbon (SOC) and bulk density (BD) were determined. The results showed that SOC was negatively correlated with λ and D and positively with ρ and C. Significantly higher values of SOC and lower BD were observed for AGF, TP, GB and PF compared to the COS. Similarly, the λ and D were significantly higher and ρ and C were lower under COS compared to conservation practices. The results suggested that a higher 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 at deeper soil depths which could help to conserve more moisture as well as assist in increasing the longevity of SOC in the soil matrix. Results imply that buffers and perennial vegetation help to reduce heat flow by increasing the thermal heat capacity and potentially mitigate climate change.