Evaluating the effects of cotton intercropping on cool-season perennial forage persistence, forage mass, and nutritive value in the southeastern United States

Integrated forage–row cropping systems provide important agronomic and economic benefits to producers. However, little attention has been given to incorporating forages into row crop systems unique to the southeastern United States. This study assessed the viability of intercropping cotton (Gossypium hirsutum L.) on perennial, cool-season legumes during the summer months in the Southeast Coastal Plain over two production years. Treatments included a weedy fallow, annual ryegrass (ARG; Lolium multiflorum Lam.) monoculture, a red clover (RC; Trifolium pratense L.) and white clover (WC; Trifolium repens L.) mixture, and a three-species mixture of ARG, RC, and WC. Plots were established in fall 2020 with forage grown until May 2021 and 2022, when plots were strip-tilled and planted with cotton. Cotton was managed with minimal herbicide use to preserve perennial clovers. Results indicated WC was more persistent than RC (>40 plants m⁻² vs. <40 plants m⁻²), and the presence of perennial clovers suppressed weeds at similar levels to the ARG monoculture (35 weeds m⁻²) during the second spring. Perennial clovers grew taller (4–5 cm) when mixed with ARG. The presence of clovers mixed with ARG during the second spring reduced acid detergent fiber (ADF) concentration and increased crude protein (CP) concentration (280 g ADF kg⁻¹; 167 g CP kg⁻¹) compared to the ARG monoculture (315 g ADF kg⁻¹; 126 g CP kg⁻¹). Benefits of intercropping perennial forages with cotton were maximized during the second year of growth, but future work is necessary to improve stand survival.