Sorghum–Cotton Rotation Reduces Weed Pressure and Improves Cotton Productivity in the Texas High Plains

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 the evolution of 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 lower weed density, biomass and reduced competition. Overall, integrating sorghum into cotton-based systems reduced weed pressure, increased cotton plant height and biomass, improved lint and seed yield, and minimized yield losses under limited weed control, supporting more sustainable production in the THP.