Cover Crop and Nutrient Management Strategies for Organic Agriculture in the Texas Plains

Abstract

The Texas Southern Plains is an important region for organic cotton (Gossypium hirsutum) and peanut (Arachis hypogea) production, growing over 90% of the United States organic crop for each. Organic management presents significant challenges to producers because they are prohibited from applying most forms of synthetic fertilizers and pesticides, but other common organic practices such as cover cropping and manure application could improve soil health. Cover crops can improve nutrient cycling, increase soil water holding capacity and suppress weed populations by increasing early season ground cover. However, sufficient cover crop herbage mass production is challenging in low rainfall regions such as the Texas Plains. Manure is an important source of nutrients for organic producers, although most nutrients in manure are in organic forms and must be mineralized to become plant available. Some manure transformations in soil, however, can lead to decreases in plant available nutrients and result in the production of greenhouse gases. Alternative manure application techniques, such as subsurface application, can impact nutrient dynamics and greenhouse gas production. The goal of this study was to determine cover crop mixtures which provide the greatest agronomic and soil health benefits to organic and conventional producers of the Texas Southern Plains, as well as assess the benefits and drawbacks of subsurface compared to surface composted manure application. The findings in this study indicate that cover crops can improve soil health in both conventional and organically managed peanut systems, with the greatest benefit coming from mixtures including cereal rye. Organic management also results in greater soil health compared to conventional, but with lower yields. Nitrogen availability is significantly impacted by manure compost application method, which can also increase greenhouse gas emissions when applied subsurface.