Changes in Soil Thermal Properties Under Corn Stover Removal and Cover Crops.

A better understanding of how soil thermal properties change under different management practices such as corn (Zea mays L.) stover removal and cover crop use is needed for the adaptation of current practices to increasing climatic fluctuations. Corn stover is being removed for expanded uses such as cellulosic biofuel production and feed for cattle. Cover crops have been suggested as a practice that can ameliorate the negative effect of corn stover removal. There is limited information available on how soil thermal properties respond to both management practices. Thus, we conducted a study to assess changes in soil thermal properties in response to corn stover removal with and without cover crops on a 6-year irrigated no-till continuous corn experiment in south central Nebraska. The treatments were: 1) no stover removal with cover crop, 2) stover removal with cover crop, 3) stover removal without cover crop, and 4) control (no stover removal without cover crop). The cover crop used was winter cereal rye (Secale cereale L). Three soil thermal properties will be measured including: 1) soil thermal conductivity, 2) thermal diffusivity, and 3) volumetric heat capacity in addition to surface soil temperature (top 5 cm). These properties will be measured in the field and in the laboratory. Field measurements will be done throughout the growing season in 2016 to capture any temporal changes in thermal properties. Laboratory measurements will be done on intact soil cores collected in spring 2016. Each thermal property will be measured at four different matric potentials (0, -0.033, -1.5 MPa). We expect that there will be significant differences in thermal properties between residue removal and cover crop treatments. Correlations of soil thermal properties with other soil physical properties and soil organic matter will be studied to develop predictive equations. Results will be available prior to the Annual Meetings.