Submitted to: International Conference on Water Resources Engineering Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/9/1999
Publication Date: N/A
Citation: N/A Interpretive Summary: Land application of animal wastes is viewed as a mechanism for both disposing of the wastes and supplying nutrients for crop growth. However, pollution of surface and ground waters associated with land application of animal wastes is of growing environmental concern. High nitrogen (N) loading rates to soils and waters can be associated with intensive animal operations. Concentrations of N in excess of 10 mg/L in the nitrate-N form render groundwater unsuitable as drinking water for humans. High N and phosphorus (P) concentrations entering streams or lakes may contribute to eutrophication. Currently much research is focusing on use of upland agricultural fields for animal waste disposal and utilization. There is also increasing interest in providing sinks for nonpoint source pollution within agricultural watersheds. Examples of such sinks include sediment detention basins, constructed wetlands, and riparian buffer systems. Past research has shown that grass filter strips can effectively reduce pollution from animal wastes and that riparian buffer systems can effectively reduce nonpoint pollution entering surface waters from upland agricultural fields. Fundamental questions exist regarding the nutrient and microbial processes of riparian zone buffers on animal wastes entering from upland areas, and the feasibility of using overland flow of wastewater in riparian zone buffer systems for animal waste treatment.
Technical Abstract: We investigated the survival total and fecal coliform bacteria in surface runoff, soil water and shallow groundwater after application of swine waste to 30 m riparian filterstrips growing 20 m grass/10 m forest, 10 m grass/20 m forest and 10 m grass/20 m maidencane in Southern Georgia during each season of the year. Total and fecal coliform bacteria in wastewater immediately prior to application was 2-3 orders of magnitude higher than in surface runoff on the day of waste application regardless of vegetation type or season. Populations of total and fecal coliform bacteria in surface runoff did not decline as water moved downslope regardless of vegetation type or season of the year. Total and fecal coliform bacteria were usually, but not always higher in groundwater in wells 5 and 10 m than soil water sampled at 30 m from the inflow point regardless of vegetative treatment or season of the year. Total and fecal coliform bacteria in soil water and shallow groundwater declined by approximately one order of magnitude every 7 days regardless of vegetative treatment or season of the year. Total coliform bacteria in 2.0 wells correlated with groundwater temperature and soil moisture (r squared = 0.89). Fecal coliform bacteria in 2.0 wells also correlated with temperature and moisture (r squared = 0.76).