Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/1/2006
Publication Date: 1/1/2007
Citation: James, E., Kleinman, P.J., Veith, T.L., Stedman, R., Sharpley, A.N. 2007. Phosphorus contributions from pastured dairy cattle to streams of the Cannonsville Watershed, New York. Journal of Soil and Water Conservation. 62(1):40-47. Interpretive Summary: Transfers of phosphorus from agricultural lands to water are a major concern, due to eutrophication. Little information is available on the impact of pastured cattle, particularly those with stream access, on nutrient loadings to streams. This study sought to quantify the phosphorus loadings from pastured dairy cattle fecal deposits to streams in the Cannonsville Watershed of New York State. Based upon field observations and spatial modeling, deposition of manure into streams by pastured dairy cattle was estimated to contribute an amount equivalent to 12% of all phosphorus loads attributed to agriculture. To date, implementation of the Conservation Reserve Enhancement Program (CREP), is estimated to have reduced in-stream deposition of phosphorus in manure by 32%. This study highlights the importance of stream bank fencing programs in controlling phosphorus loadings from pastured cattle.
Technical Abstract: Accelerated eutrophication of surface waters due to phosphorus (P) loadings from livestock agriculture is a widespread water quality problem and is of particular concern in the Cannonsville Reservoir, of New York State. This study sought to quantify fecal P contributions to streams from pastured dairy cattle in the Cannonsville Watershed. Four pastured dairy herds with stream access were observed over four intervals during the spring and summer of 2003. Cattle behavior, including in- and near-stream deposition of feces, was recorded and manure samples collected from each herd for nutrient analysis. Patterns of fecal deposition within a pasture were related to the number of cattle and amount of time cattle spent in particular areas. On average, approximately 30% of all fecal deposits expected from a herd were observed to fall on land within 40-m of a stream, and 7% fell directly into streams. The rate of in-stream fecal deposition on a per-cow basis was significantly higher than in other areas of a pasture. Based upon consistency in observed fecal depositions between pastures, a pair of simple equations was developed to predict fecal P and N deposition in other pastures of the Cannonsville Watershed as a function of number of cattle, time in pasture, and type of cattle (heifers vs. milk cows). Approximately 90% of the dairy farms in the watershed were considered, using spatial databases of streams, pasture boundaries, and livestock characteristics. The equations predict approximately 3,600 kg (7,936 lbs) P are deposited directly into streams and 7,650 kg (16,865 lbs) P within ten meters (32.8 ft) of flowing water from the 11,000 dairy cattle in the watershed. At this magnitude, these loadings represent a significant environmental concern, with in-stream deposits equivalent to approximately 12% of watershed-level P loadings attributed to agriculture. Recent efforts to exclude cattle from streams as part of the Conservation Reserve Enhancement Program (CREP) were estimated to have already reduced in-stream deposition of fecal P by 32%. Even so, considerable opportunity remains for targeted implementation of cattle exclusionary practices to further improve the quality of surface waters in the Cannonsville Watershed.