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Title: Tradeoffs between production and perennial forages in dairy farming systems vary among counties in the Northeastern United States

Author
item Egan Jr, John
item Goslee, Sarah
item Orr, Aimee

Submitted to: Agricultural Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2015
Publication Date: 10/1/2015
Citation: Egan Jr, J.F., Goslee, S.C., Orr, A.N. 2015. Tradeoffs between production and perennial forages in dairy farming systems vary among counties in the Northeastern United States. Agricultural Systems. 139:14-28.

Interpretive Summary: Dairy farms that grow more perennial vegetation for grazing pastures or conserved forages can help conserve soil, protect water quality, and provide habitat for wildlife. However, they often sacrifice milk production relative to farms feeding higher amounts of grain and corn silage. We developed a new approach to estimating milk production at broad, county-wide scales in the Northeastern US. Our analysis showed that increasing perennial forage yields could substantially improve milk production, and highlighted opportunities to exceed current milk production levels while also expanding land cover in perennial vegetation.

Technical Abstract: Dairy farms that grow more perennial vegetation for grazing pastures or conserved forages can offer many environmental benefits but may show reduced milk production relative to systems feeding higher amounts of grain and corn silage. Because yields of annual and perennial crops vary with soil type, an accurate comparison of the productive potential of these systems over county or regional scales requires taking into account spatial variation in soil quality. In this study, we present a novel approach to leverage data from soil maps and satellite imagery to calculate the productive potential of dairy rations incorporating varying amounts of perennial forages for a sample of five counties in the Northeast United States. Results indicate that high corn silage rations produced 22 to 168% more milk per hectare of farmland than grazing rations, but variation among counties was much greater than variation among rations, with the best county (Lancaster, PA) producing as much as 4.8 times more than the least county (Orange, VT). Comparison of scenarios involving all local crop production versus scenarios with grain imports showed that large amounts of corn and soybean imports are needed to meet current levels of milk production using any ration. Restricting grain imports to prevent excess Phosphorous and nutrient pollution resulted in a 0-10% decrease in milk production relative to unlimited imports, but still produced far more milk than in the all local production scenarios. Sensitivity analysis of the model showed that milk production in each county was very responsive to changes in perennial forage yields (especially for grazing rations), responsive to changes in average daily milk production, and generally not responsive to changes in the productive lifetime of lactating cows. This study demonstrates a persistent tradeoff between perenniality and production in dairy systems, but suggest that opportunities may exist to sustain or exceed current milk production levels in the Northeast while also expanding land cover in perennial vegetation.