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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Adaptive Cropping Systems Laboratory » Research » Publications at this Location » Publication #422236
Research Project: Developing Practices for Nutrient and Byproducts to Mitigate Climate Change, Improve Nutrient Utilization, and Reduce Effects on Environment (BRIDGE PROJECT)

Location: Adaptive Cropping Systems Laboratory

Title: Over-seeded cool-season annuals for cover crop or forage roles in warm-season perennial grass pastures

Author
item HAN, KUN-JUN - LSU Agcenter
item ALISON, MONTGOMERY - LSU Agcenter
item MACOON, BISOONDAT - National Institute Of Food And Agriculture (NIFA)
item Fultz, Lisa
item NEGRETE, POALA - LSU Agcenter
item PITMAN, WILLIAM - LSU Agcenter

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/2025
Publication Date: 9/5/2025
Citation: Han, K., Alison, M.W., Macoon, B., Fultz, L.M., Negrete, P., Pitman, W.D. 2025. Over-seeded cool-season annuals for cover crop or forage roles in warm-season perennial grass pastures. Agronomy Journal. https://doi.org/10.1002/agj2.70157.
DOI: https://doi.org/10.1002/agj2.70157

Interpretive Summary: Winter annuals can serve a variety of purposes in perennial warm-season pastures from winter forage to nutrient retention. Overseeding winter pastures with a variety of winter annuals including legumes, grasses, and mixes of legumes and grasses was tested at three locations in Louisiana and Mississippi. Legumes provided greater N in their aboveground biomass than grass treatments. Despite the increased N from winter legumes, perennial bermudagrass did not seem to benefit from added N, likely due to N immobilization by the microbial community and a difference in timing between bermudagrass needs and degradation of winter annual biomass.

Technical Abstract: Over-seeded annual grasses and legumes, which can provide forage on dormant perennial warm-season grass pastures, serve as cover crops on fallow cropland. Although erosion control is not a typical need for pastures with perennial grass sod, cover crops functioning as catch crops to reduce cool-season nutrient loss or legumes for N fixation could contribute to reduced-cost warm-season pasture growth. Treatments of over-seeded cool-season species and management evaluating effects of cover crop removal as forage versus mulched as a N source were evaluated at three locations in three years. Cool-season legumes produced more biomass N than cool-season grasses indicating biological N contributions of the legumes. Nitrogen limitation of the less productive, non-fertilized grasses indicates that readily available soil N had been depleted limiting N leaching. Despite mulching of legume biomass with N amounts of 45 to 89 kg ha-1, biomass production of bermudagrass in the following growing season was not increased. Lack of benefit of cover crop N contributions to subsequent bermudagrass forage production indicates that availability of increased soil N was not synchronized with periods of efficient bermudagrass N uptake. These unanticipated results appear to be due to N mineralization-immobilization processes associated with soil microbial community dynamics and variable weather effects on bermudagrass growth in this warm, humid, but uncertain environment.