Weed Control and Cotton Yield Response under Sorghum-Cotton Rotation

The Texas High Plains (THP) is a major cotton-producing region facing challenges from continuous cotton monoculture, which has increased weed pressure and reduced system sustainability. Over 90% of cotton acreage relies on herbicides, accelerating herbicide-resistant weed development. Declining Ogallala Aquifer water levels and erratic rainfall further stress the system, highlighting the need for diversified, drought-resilient cropping systems. Sorghum, known for its drought tolerance and allelopathic properties, offers an effective rotational crop to suppress weeds and improve water-use efficiency. This study evaluated the effects of sorghum-cotton rotation on weed dynamics, crop growth, and yield. A two-year field experiment (2024-2025) was conducted at the Quaker Research Farm, Texas Tech University, Lubbock, TX, using a split-plot design with crop rotations [sorghum-cotton (S-C), sorghum-sorghum (S-S), and cotton-cotton (C-C)] as main plots and weed management treatments (weeded and unweeded) as subplots, with four replications. Results showed that the C-C system had 41% higher weed density and 57% greater early-season biomass than S-C; cotton growth improved in S-C with 17-22% taller plants and 36-90% more biomass compared to cotton monoculture. Under weeded conditions, lint yield increased by 53% and seed yield by 30% compared with cotton monoculture. Under unweeded conditions, yields were 21% to 41% greater in the S-C system due to improved weed suppression and reduced competition. Overall, integrating sorghum into cotton-based systems reduced weed pressure, enhanced crop performance, and minimized yield losses under limited weed control, supporting more sustainable production in the THP.