Proceedings of the 2019 Mississippi Water Resources Conference

Year: 2019 Authors: Feng G., Reginelli D.

Soil health management is essential for sustainability of agricultural production system. Cover crop, manure and biochar have been widely applied for improving soil organic carbon (SOC). However, no consistent results were found whether and how much increasing SOC could improve water holding capacity of different soils. We conducted both field and simulation studies to determine impact of cover crop and amendment of poultry litter and biochar on SOC, soil water content at field capacity (FC) and water use efficiency (WUE). The results revealed that average annual percolation under the wheat cover crop system was decreased by 11%, over 8 decades as compared with the plots without cover crop. Soybean yield and water use efficiency (WUE) were increased by 4% and 9% in the cover crop-based cropping system. Growing a winter wheat cover crop between harvest and planting of soybean improved soil organic carbon by 15%. Application of poultry litter increased SOC ranging from 0.6 to 2.6%. A significant positive linear relationship was found between total carbon (TC) and FC of silt and silty loam soils as TC exceeded 1%. We found that a 1% increase in soil TC can improve soil water holding capacity by 13%. For different soil textures, a strong linear positive relationship was found in coarser soils (clay <20%). The soils from Brooksville had higher carbon content (mean value, 1.59%) and higher FC (34.64%) partly due to manure application than unmanured soils from Stoneville (TC of 0.92% and FC of 30.40%) in Mississippi State. We suggest soil carbon should be increased over 1% by applying manures and biochar or by other means to improve soil water holding capacity and overall soil health.