Evaluating Intensified Forage Systems for Water, Soil, and Nutrient Retention in the Southern Great Plains

Highlights Integration of warm-season forages into winter wheat–fallow systems reduced runoff and sediment export by >60% Grazed systems had higher runoff and nutrient loss but less sediment yield compared to hayed systems. Species-rich rotations enhance water, soil, and nutrient retention relative to monoculture systems. Intensive grazing with rest phases can reduce sediment and runoff by over 30% relative to a continuous grazing system. 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 loss, 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 demonstrate 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 reduce average annual runoff and sediment loss by >60% and nutrient export by >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, provide modest reductions in runoff generation potential but significantly lowered sediment and nutrient losses—>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.