Nutrients in ground and surface water on intensive grazing and confined feeding dairy farms. (S11-gilker855099-oral)
Authors:
R.E. Gilker* - Univ. of Maryland R.R. Weil - Univ. of Maryland
Abstract:
A growing number of dairy farmers in the Northeast are adopting management intensive grazing (MIG) for improved quality of life and profitability. Consideration of MIG as a Best Management Practice (BMP) is controversial. Compared to growing row crops for confined feeding systems, MIG improves soil quality and reduces erosion. However, studies indicate that MIG might lead to excessive nitrogen leaching, especially due to high N concentrations under urine spots from grazing cows. These studies either used monolith lysimeters, which may affect water flow, or were carried out in pastures with high N fertilization rates. Our study in Maryland involves two watersheds on a confined feeding dairy farm and four watersheds on two MIG farms. Transects of piezometer nests were installed in each watershed to monitor groundwater under cropland and pastures. In May 2001, we began collecting samples biweekly from piezometers and from streams flowing through two of the grazed watersheds. For the 2002-2003 leaching season, groundwater in the MIG watersheds averaged 6.0 mg/L NO3-N and 0.006 mg/L for dissolved PO4-P. Stream samples averaged 2.6 mg/L NO3-N and 0.001 mg/L for dissolved PO4-P with no increase as the streams transversed the watersheds. These results indicate that nutrient concentrations leaving the grazed watersheds are below EPA guidelines, and suggest MIG is suitable as a BMP.
Speaker Information: Rachel Gilker, Univ. of Maryland, UMD-NRSL 1112 H. J. Patterson Hall, College Park, MD 20742; Phone: 301-405-8922; E-mail: [email protected]
Session Information: Tuesday, November 4, 2003, 1:25 PM-3:00 PM Presentation Start: 1:30 PM
Keywords: dairy farm; intensive grazing; water quality; nutrient management
