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 Institute For Advancing Health Through Agriculture; Hunt, Sherry; Zhang, Xunchang; Busteed, Phillip; JEONG, JAEHAK - Texas A&M University Institute For Advancing Health Through Agriculture

Submitted to: Journal of Natural Resources and Agricultural Ecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2026
Publication Date: 4/28/2026
Citation: Kikoyo, D., Fortuna, A., Smith, P., Hunt, S., Zhang, X.J., Busteed, P.R., Jeong, J. 2026. Evaluating intensified forage systems for water, soil, and nutrient retention in the Southern Great Plains. Journal of Natural Resources and Agricultural Ecosystems. 4(2): 35-45. https://doi.org/10.13031/jnrae.16562.
DOI: https://doi.org/10.13031/jnrae.16562

Interpretive Summary: The Southern Plains (SP) encompasses portions of Kansas, Oklahoma, and northern Texas, representing more than 9 million hectares (ha) of cropland planted primarily to winter wheat that provides grain, hay, pasture, or a combination of these managements. Agriculture in the SP is driven in part by the timing and quantity of precipitation. Variable precipitation often reduces the potential for diversifying forage crops and limits prevailing grazing systems. Incorporating mixed cool-and warm-season cover crops can potentially reduce forage shortages, enhance ground cover as well as reduce sediment and nutrient losses. Adoption of intensive grazing systems that allow for multiple grazing rotations, can improve pasture utilization, enhance soil structure, and facilitate nutrient recycling. This research investigates the influence of such sustainable agricultural practices on water, soil, and nutrient retention in SP agriculture systems under diverse climatological conditions. The computer software Agricultural Policy/Environmental eXtender (APEX) and over 30 years of measured data were used to simulate impacts of adopting several alternative forage crop systems, managed either for grazing or haying, on edge-of-field water discharge and water quality. Our results verify that integration of warm-season forages into winter wheat–fallow systems reduced runoff and sediment export by more than 60%. Grazed systems had higher runoff and nutrient loss, but less sediment yield compared to hayed systems. Species-rich rotations enhanced water, soil and nutrient retention relative to monocrop systems. In addition, intensive grazing with rest phases can reduce sediment and runoff by over 30% relative to a continuous grazing system. Alternative forage mixes and grazing systems could be adopted across approximately 5.4 million ha of the SP.

Technical Abstract: A clearer understanding of how forage management and grazing scheduling decisions mitigate or exacerbate agriculture’s environmental footprint is critical for advancing management practices that enhance productivity while reducing ecological impacts. This study applies the Agricultural Policy/Environmental eXtender model to evaluate environmental outcomes by simulating edge-of-field runoff, soil retention, and nutrient export from 1.6-ha field plots in El Reno, Oklahoma, and compares the effects of alternative forage and grazing management strategies relative to prevailing grazing systems typical of the Southern Great Plains ecoregion. Results demonstrated that rotational forage systems—whether implemented as monocultures (e.g., winter wheat (Triticum aestivum)–sorghum Sudan grass (sorghum bicolor x S. bicolor var. Sudanese)) or species mixtures (e.g., winter wheat/rye (Secale cereale)–sorghum/soybean (Glycine max))—substantially reduced average annual runoff and sediment loss by greater than 60%, and nutrient export by greater than 14% compared to prevailing winter wheat systems during dry, normal, or wet climatological conditions. Additionally, grazing strategies characterized by high stocking densities and short-duration grazing, interspersed with forage recovery periods, provided modest reductions in runoff generation potential but significantly lowered sediment and nutrient losses greater than 30% reductions relative to continuously grazed systems with moderate stocking rates. These findings underscore the potential of sustainable forage and livestock intensification systems to effectively manage upstream runoff, reduce nonpoint source pollution, and promote long-term environmental stewardship and climate resilience across agricultural landscapes. This study illustrates that forage management and grazing scheduling decisions can exert a pivotal influence on hydrologic processes, erosion, and nutrient loss dynamics within managed grazing systems and addresses the existing gap in forage system designs that emphasize multi-seasonal land cover and forage rest-driven grazing schedules.