Evaluating intensified forage systems for water, soil, and nutrient retention in the Southern Great Plains

Authors: KIKOYO, DUNCAN - Texas A&M University Institute For Advancing Health Through Agriculture; Fortuna, Ann-Marie; SMITH, PATRICIA - Texas A&M University; Hunt, Sherry; Zhang, Xunchang; Busteed, Phillip; JEONG, JAEHAK - Texas A&M University Institute For Advancing Health Through Agriculture

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/28/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Integrated crop and pasture-based livestock systems can benefit from alternative management practices that address nutritional needs of livestock, mitigate climate impacts, and minimize environmental degradation. Incorporating cool- and warm-season mixed forage cover crops offers a solution to forage shortages while enhancing ground cover, potentially reducing sediment and nutrient losses. This study assessed the impacts of cool- and warm-season mixed forage intensification systems on water, soil, and nutrient retention in the variable climatic conditions of the Southern Great Plains agroecosystems. Using the Agricultural Policy/Environmental eXtender (APEX) model, summer and winter forage crop rotation systems in grazed and hayed watersheds were simulated and compared to single-crop tilled systems on 1.6 ha watersheds in El Reno, OK. We represented the mixed forage cover crops in APEX using the dominant crop in the forage mixture measured for six consecutive years. The cool season forage biomass was >50% winter wheat (Triticum aestivum) and ~50 to 25% triticale (Secale x Triticum) on a dry weight basis. The dominant crop in the summer forage mixture was 70 to 90% sorghum sudangrass (sorgham bicolor x S. bicolor var. Sudanese) on a dry weight basis. During (1997-2006) winter wheat followed sorghum sudangrass numerous times. Results demonstrated that intensified alternative warm- and cool-season forage systems, either grazed or hayed, can enhance water, soil, and nutrient retention compared to prevailing conventionally tilled winter wheat. Over a 30-year simulation period (1977-2006), no-till winter wheat-sorghum rotations that incorporated multiple harvests increased retention of water by 16.4%, soil by 10.8%, nitrogen by 11.4%, and phosphorus by 9.6%, compared to conventionally tilled winter wheat with a single harvest. Conversely, multiple grazing operations improved water retention (by 15.9%) but resulted in increased soil and phosphorous losses (by 5.9% and 14.9% respectively) whereas changes in nitrogen losses were marginal. The benefits of intensified systems were more pronounced in dryer years (those with annual rainfall totals below the 25th annual precipitation percentile during the simulated period) compared to wet years (above 75th percentile), emphasizing their potential for improving drought resilience and environmental stewardship. These findings offer valuable insights for policymakers, farmers, and stakeholders to promote sustainable agricultural practices, enhance productivity, and mitigate soil and nutrient-related environmental impacts in the Great Plains. USDA is an equal opportunity provider and employer.