Increasing Cropping Systems Resilience with Cover Crops
Preliminary data from a three-year Southern Sustainable Agriculture Research and Education Grant has found that cover crops may help buffer against extreme soil temperature changes, in addition to providing a myriad of other benefits, such as improved soil health, reduced soil erosion and increased water-holding capacity. The findings may help to increase cropping systems resilience in the face of extreme weather changes.
Researchers with Middle Tennessee State University, Auburn University and University of Kentucky are evaluating the influence of cover crops on soil thermal properties and heat capacity and how these may influence crop productivity. Other soil health indicators were also analyzed, including water retention, bulk density, pore size distribution, organic carbon, soil pH, and microbial biomass.
“Rising temperatures may affect the soil ecosystem services, crop productivity and agricultural and environmental sustainability,” said Samuel Haruna, Middle Tennessee State University assistant professor in soil science and the project’s principal investigator. “Therefore, it is important to identify soil and crop management practices that are more adaptive to a changing climate.”
Two farmer fields, located in Tennessee, contained two treatments (cover crops vs. no cover crops) with three replicates of each treatment. Thermal sensors and heat flux plates were installed in both treatment plots. In addition, soil temperature and water content sensors were installed after cover crops were planted. Soil samples were taken before and after cover crop planting, and after cover crop termination.
Results showed that while soil properties were similar between cover crop and no cover crop management just before cover crops were planted, these properties were significantly different prior to cover crop termination.
For example, bulk density was 18 percent higher under no cover crop management compared to the cover crop treatments prior to termination. Haruna said that was attributed to the roots of cover crops opening up soil pores and also due to the higher soil organic carbon under cover crop management (organic carbon was 14% higher under cover crop compared with no cover crop management).
“No cover crop management significantly increases thermal conductivity and thermal diffusivity. Further, as a result of higher soil organic carbon and water content, volumetric heat capacity was 21% and 14% higher at saturation and field capacity under cover crop compared with no cover crop management,” said Haruna. “This demonstrates that cover crop management can buffer against significant heat transfer within the soil, helping to keep the soil temperature stable for longer periods.”
Other results found that water infiltration was 52 percent higher prior to cover crop termination and 68 percent higher two months after termination compared with the no cover crop treatments. This suggests that cover crops can increase soil water infiltration and persist after cover crop termination.
Further, measured saturated hydraulic conductivity was numerically higher under cover crops compared with no cover crop management, demonstrating that cover crops can reduce surface runoff and soil loss while increasing water infiltration and storage, and, thus, potentially improving crop productivity.
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The Tennessee SARE program is facilitated through a joint collaboration between the University of Tennessee Institute of Agriculture and Tennessee State University Cooperative Extension. We work together to deliver a program that enhances the environmental, social, and economic sustainability of the state through research and education. Tennessee SARE partners with researchers, extension faculty, producers, and community organizations to research and implement the best science-based practices available in all aspects of Tennessee's agricultural system. In addition to research, SARE is dedicated to providing education in sustainable agriculture through various trainings offered each year.
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