Long-Term Effects of Peanut-Cotton-Forage Rotation on Cotton Yield and Soil Organic Matter

In the southeastern Coastal Plain, an annual rotation of cotton (Gossypium hirsutum L.) and peanut (Arachis hypogaea L.) is common.  This rotation often results in erosion and loss of soil organic carbon (SOC), especially with tillage.  Incorporation of two years of perennial grasses, such as bahiagrass (Paspalum notatum Fluegge), into the peanut-cotton rotation (also called a sod-based rotation or integrated forage-row crop rotation) has shown to increase SOC, particularly in conjunction with conservation tillage practices.  Cattle grazing is also recommended to provide improved income while land is in the forage phase of the rotation.  The objective of this study was to evaluate the crop yield in an established rotation system to determine the effect of added forage and grazing long-term.  Production systems included a continuous rotation of peanut-cotton with grazing (PCG) and without grazing (PCN) and an integrated rotation of peanut-cotton-bahia1-bahia2 (FR) with grazing (FRG) and without grazing (FRN).  In all systems, conservation practices were used (i.e., strip tillage and oat/rye winter cover cropping).  The long-term effects were evaluated following 8 years of establishment (i.e., two complete rotations of the 4-year FR) from 2010 to 2017 and compared to the PCN.  Yield of cotton increased by 23% with PCG, 19% with FRN, and 33% with FRG compared to PCN.  Yield of peanut increased by 26% with PCG and 40% with both FRN and FRG compared to PCN.  As of 2012, the concentration of SOC was still increasing in these systems due to conservation practices (e.g., winter cover cropping).  Soil organic carbon in the FR was found to be nearly double that of PC at 0-5 cm depth.  Results suggest that the addition of cattle and/or perennial grasses to the peanut-cotton rotation can improve crop productivity in the long-term.