Cover cropping and interseeding management practices to improve runoff quality from dairy farms in central Pennsylvania

Authors: BARNES, RYAN - Pennsylvania State University; Rotz, Clarence - Al; PREISENDANZ, HEATHER - Pennsylvania State University; WATSON, JACK - Pennsylvania State University; ELLIOTT, HERSCHEL - Pennsylvania State University; Veith, Tameria - Tamie; Williams, Chilton; BRASIER, KATHRYN - Pennsylvania State University

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2021
Publication Date: 5/4/2021
Citation: Barnes, R.G., Rotz, C.A., Preisendanz, H.E., Watson, J.E., Elliott, H.A., Veith, T.L., Williams, C., Eaton, W., Brasier, K. 2021. Cover cropping and interseeding management practices to improve runoff quality from dairy farms in central Pennsylvania. Transactions of the ASABE. 1-34. https://doi.org/10.13031/trans.14329..
DOI: https://doi.org/10.13031/trans.14329.

Interpretive Summary: Dairy farms in the United States are under increasing pressure to adopt best management practices to improve water quality while remaining profitable. Cover cropping and interseeding are best management practices that dairy farmers can adopt to maintain soil cover beyond the corn growing season, thereby reducing nutrient and sediment losses from fields during surface runoff events. Water quality and economic impacts of using cover cropping or interseeding were investigated for dairy farms representative of those in Central Pennsylvania using the Integrated Farm System Model (IFSM). Farm simulations suggest that interseeding generally out performs cover crops in reducing nitrogen, phosphorus, and sediment losses relative to a baseline of no cover crop or interseeding, and additional costs for these practices increased total farm production costs by no more than 2%. These results, representative of dairy farms in the Mid-Atlantic region of the United States, suggest that whenever possible, cover cropping or interseeding following corn production should be encouraged as a cost-effective best management practice on dairy farms.

Technical Abstract: Intensive agricultural activities are known to increase nutrient and sediment losses, leading to degraded water quality in receiving water bodies. In the Chesapeake Bay watershed, reducing nutrient and sediment losses from animal operations are necessary to meet the Bay’s mandated load reduction goals. Here, the Integrated Farm System Model (IFSM) was used to investigate the potential water quality benefits and economic impacts of adopting cover cropping or inteseeding for eight dairy farms representative of common operations in central Pennsylvania (PA). The modeled farms represented confined, organic, grazing, and Amish farming practices for dairy herds ranging in size from 35 to 150 lactating Holstein cows. Simulations were run for 25 years using observed weather data for Mifflin County, PA and for two dominant agricultural soils series in the county: Hagerstown silt loam and Opequon silty clay loam. Model output included water balance results, nutrient and sediment loads, and farm-scale economics at an annual scale. Overall, the simulation results showed that interseeding enhanced reduction of N, P, and sediment compared to cover cropping. The economic impacts of cover crop and interseeding varied among farm types, but nearly all scenarios resulted in a net loss in revenue compared to the baseline scenario. However, the changes were generally minor, with losses of no more than ~6% for cover cropping and 14% for interseeding. Results suggest that many dairy farmers could adopt interseeding, but the benefits are likely to be greater for confined or semi-confined, rather than grazing or Amish, operations. Interseeding necessitates purchasing additional equipment or modifying existing equipment. These results have implications for cost-share incentive structures aimed at promoting adoption of cover crops and interseeding, especially for confined farms, which are likely to experience financial losses if these practices are adopted.