Submitted to: International Symposium on Agricultural & Food Processing Wastes Proceeding
Publication Type: Proceedings
Publication Acceptance Date: 10/20/2002
Publication Date: 10/20/2002
Citation: HUBBARD, R.K., NEWTON, G.L., VELLIDIS, G., GASCHO, G.J., LOWRANCE, R.R. LONG-TERM IMPACT OF DAIRY LAGOON WASTEWATER ON SHALLOW GROUNDWATER QUALITY. INTERNATIONAL SYMPOSIUM ON AGRICULTURAL & FOOD PROCESSING WASTES PROCEEDING. Moore, J.A.(ed.) Animal, Ag. and Food Process Wastes. ASAE, St. Joseph, MI. p. 229-235. 2002. Interpretive Summary: Contamination of soils, surface waters, and ground waters from animal wastes is an environmental concern. Intensive animal operations can result in high nitrogen (N) or phosphorus (P) loading rates to soils and waters. Land treatment systems for animal wastes may include application of wastewater to crops, pasture or forest, vegetated buffer systems or constructed wetlands. This research was conducted to evaluate the long term (1991-present) impacts of using dairy lagoon wastewater as a nutrient source for a multiple cropping system including corn, coastal bermudagrass, and abruzzi rye. Water samples were collected and analyzed from a network of 72 shallow wells established under the center pivot system used for wastewater application. Results showed that leaching of nitrate to 3 and 6 m depth in coastal plain soils with high clay subsoils occurs extremely slowly. Nitrate concentrations found in the groundwater at 3 and 6 m depth showed the impact of past inorganic N fertilization regimes, indicating that recommended upland agricultural practices are impacting shallow groundwater in this region. This information is useful to scientists and land managers responsible for practices which ultimately impact on soil and water quality.
Technical Abstract: A long-term study was conducted using dairy lagoon wastewater as a nutrient source for a multiple cropping system. Screened wastewater was applied at different rates (200, 400, 600 or 800 kg/ha/yr N in the waste) to the four quadrants of a center pivot area from 1991-1997, with a triple cropping system of corn, coastal bermudagrass, and abruzzi rye. In March 1997 the study was changed such that commercial fertilizer was used for two of the quadrants to compare yields and environmental impact between the inorganic nutrient source and the animal waste. Also, from 1997-1999, the study compared the original cropping system with a triple cropping system consisting of corn, tropical corn, and a mixture of rye and clover. A network of 72 shallow groundwater wells was established beneath the center pivot in 1991. Water samples have been periodically collected from these wells for more than eight years and analyzed for nitrogen and phosphorus. This paper reports the impact of the land applied wastewater and inorganic fertilizer on nitrates in shallow groundwater.