Soil Thermal Properties Influenced By Perennial Biofuel and Cover Crop Management.

Heat transport is an important edaphic factor that can influence the soil environment. This study was conducted at University of Missouri Bradford Research Center to evaluate the influence of perennial biofuel and cover crops on soil thermal properties. The experimental design included three replicate blocks in a completely randomized design with four treatments. Two treatments included two levels of cover crops [cover crops (CC) vs no cover crops (NC)] collectively called row crops (RC). Cover crops used included Cereal rye (Secale cereale), Hairy vetch (Vicia villosa) and Austrian winter pea (Pisum sativum subsp. arvense). Two treatments included perennial biofuel crops (PB): giant miscanthus (Miscanthus x gigantus) and switchgrass (Panicum virgatum), both collectively called PB. Soil samples were collected at 10 cm depth increments from the soil surface to a depth of 30 cm. Soil thermal properties [thermal conductivity (λ), volumetric heat capacity (C_V), and thermal diffusivity (D)]  and volumetric water content (θ) were determined at 0, -33, -100 and -300 kPa pressures. Additionally, soil organic carbon (SOC) were also determined. Results show that PB compared to RC had significantly higher SOC as well as θ at all pressures measured. As a result, PB had 11% higher C_V at saturation compared to RC. Cover crops compared to no cover crop had 18% higher θ at saturation and 26% higher SOC; this led to 13% higher C_V compared to no cover crop. Row crops had significantly higher λ and D compared to perennial biofuel crops. Results from the current study imply that CC and PB can change soil thermal properties; this indicates that these management systems can better handle a more variable climate.