EFFECTS OF A DAIRY LOAFING LOT-BUFFER STRIP ON STREAM WATER QUALITY
JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION , 34 , 1998
Younos, T.M., Mendez, A., Collins, E.R., Ross, B.B.
A loafing or sacrifice lot i8 an area located outside of the free stall barn, where a dairy herd spends several hours per day. Sacrifice lots are usually denuded of vegetation and have high concentrations of manure and urine that can contribute significant amounts of sediment, nutrients, and pathogens to nearby surface waters. In this study, stream water quality impacted by direct runoff from a sacrifice lot was monitored for a period of 20 months. Ambient stream water quality was monitored by grab sampling upstream and downstream of the sacrifice lot. During runoff events, stream water quality downstream of the sacrifice lot was monitored with an automatic sampler. Laboratory analyses were conducted for total suspended solids and nutrients (nitrogen and phosphorus compounds). A grass filter strip (GFS) was installed as a buffer downslope of the sacrifice lot 10 months into the study period. The impact of the buffer strip on the standardized pollutant concentrations and loads was evaluated using the non-parametric Wilcoxon test. The Wilcoxon test indicated that there was no significant difference (a = 0.05) in the standardized yield of sediment and dissolved pollutants before and after the GFS installation, except for phosphate-phosphorus and filtered total phosphorus concentrations, and sediment-bound total phosphorus and total kjeldahl nitrogen loads that decreased significantly. However, load decrease could have been partially caused by the smaller rainfall volumes after the GFS installation as compared to the existing condition.