Jac J. Varco, Mississippi State University, Mississippi State, MS and Apisit Boupai, Plant and Soil Sciences, Mississippi State University, Mississippi State, MS
Enhancing soil quality and/or health is necessary to improve sustainability of agro-ecosystems. The objective of this study was to compare selected cover crop systems with and without fall-applied poultry litter to traditional N fertilization on resulting soil properties and microbial activity. The cover crop-poultry litter systems were established each fall from 2012 through 2015, and prior to corn planting for 2014 through 2015 the area was strip-tilled. Soil core samples were taken fall 2015 to determine bulk density and total soil C and N following corn harvest, but prior to establishment of the cover crop-poultry litter systems. Beginning at planting in 2016, the soil was sampled for assessment of microbial activity using the FDA hydrolysis method every two weeks up through 4 weeks. Results indicate greater bulk density, total C and N, and total microbial activity for non-disturbed interows as compared to the corn row or area disturbed by strip-tillage. Also, soil bulk density tended to increase with soil depth; however, total C and N, and total microbial activity decreased with depth. Poultry litter applied alone had the lowest bulk density at 1.31 g/cm3. Total soil N concentration was greatest for the legume-rye bi-culture, legume with poultry litter, and rye with poultry litter systems. Total soil C was greatest for the legume-rye bi-culture and legume with poultry systems. Total microbial activity was greatest at corn planting and decreased at each sampling date through four weeks from planting apparently due to a lack of rainfall and soil drying. However, legume and legume-rye bi-culture expressed the greatest microbial activity across the sampled period. Fertilizer N rates did not result in defined relationships with measured soil properties or enzyme activity. Strong relationships at planting time were observed between soil enzyme activity and soil total C (r2=0.79) and N (r2=0.75).