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ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #91644

Title: NITRATE LEACHING FROM PASTURE SWARDS

Author
item Stout, William
item FALES, S. - PENN STATE UNIVERSITY
item MULLER, L. - PENN STATE UNIVERSITY
item Schnabel, Ronald
item Weaver, Stefan

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Management intensive grazing (MIG) is a grazing system in which animals at a high stocking density are rotated through several paddocks at short time intervals (12-24 hours) so that animal performance is maximized. Although MIG has the potential to increase dairy farm profitability in the northeast U.S., recent work in this region has shown that a substantial amount of nitrogen applied in fertilizer to pastures to increase production is leached below the root zone and into the ground water. We conducted a field study to measure nitrogen leaching from different types of pastures that received nitrogen from either fertilizer of from biological fixation from two legumes, alfalfa or white clover. We found that the least amount of nitrogen was leached from pastures receiving nitrogen from white clover, but that pasture productivity (i.e. profitability) was lowest. As pasture productivity increased in the other pasture types, so did leaching losses. Data from the study are being used in the DAFOSYM (Dairy Forage System) model to assess trade-offs between farm profitability and environmental impact.

Technical Abstract: Management intensive grazing (MIG) is a grazing system in which animals at a high stocking density are rotated through several paddocks at short time intervals (12-24 hours) so that animal performance is maximized. Although MIG has the potential to increase dairy farm profitability in the northeast U.S., recent work in this region has shown that a substantial amount of N applied as fertilizer is leached below the root zone of orchardgrass [Dactyls glomerata L., (cv.) 'Pennlate'] managed as an intensive pasture. How much N is leached from other forage species managed as intensive pasture under the climatic conditions of the northeast U.S. is not known. We conducted a field study using large drainage lysimeters to measure NO3-N leaching loss from six pasture swards: orchardgrass + N, orchardgrass + alfalfa (Medicago sativa L., (cv.) Alfagraze), orchardgrass + Ladino type white clover (Trifolium repens L.), Ryegrass [Lolium perrene L, (cv.) Citadel] + N, ryegrass + alfalfa, and ryegrass + white clover. The study site was located in central Pennsylvania on a Hagerstown silt loam soil (fine, mixed, mesic Typic Hapludalf). Nitrate-N leaching losses were most consistent under N fertilized swards where the amount of N could be adjusted for yearly weather conditions. In a drought year, NO3-N leaching increased dramatically in swards containing alfalfa or white clover.