Monday, November 13, 2006 - 11:30 AM

How Good is Nutrient Management Data Collected on Wisconsin Dairy Farms?.

J. M. Powell, USDA-ARS, Dairy For. Res. Ctr., Univ Wisconsin atb Madison, 1925Linden Dr W, Madison, WI 53706 and Douglas Jackson-Smith, Utah State Univ, Dept of Sociology, Social Work and Anthropology, 216 H Old Main Bldg, Logan, UT 84322.

With recent and impending passage of government regulations pertaining to environmental impacts from animal agriculture, many livestock producers are seeking new ways to track and improve the management of nutrients contained in feed and manure. An on-farm study of fifty-four representative Wisconsin dairy farms was conducted to evaluate the influence of biophysical and socioeconomic factors on overall feed, fertilizer, and manure nutrient use. This presentation provides answers to (1) how well data on cow diets, feed analyses and milk production reflected established feed-milk-manure relationships; and (2) how well farmer-recorded data on manure spreading reflected literature values of manure nitrogen (N) and phosphorus (P) excretion, collection and loss. Calculated feed N and P use efficiencies (18-33% and 18-35%, respectively) fell within ranges expected for dairy farms. This suggested that our on-farm methods of data collection provided reliable information on relationships between N and P intake, secretions in milk, and excretion in manure. On stanchion farms, there were no differences (P<0.05) between farmer estimates (kg farm-1) of manure P collected (1140) and spread (1210), or what would be calculated from the literature (1340). On free-stall farms, there were no differences in amounts of manure P collected (2889), spread (2350), or literature estimates (2675). Manure P applications (kg/ha) to tilled cropland would be similar (P<0.05) using either farmer estimates of manure collected and spread, or literature estimates. The data provided a fairly accurate snap-shot of Wisconsin industry practices, as well as fairly accurate information on the range of feed and manure management practices on individual dairy farms. Improvements to data collection methods would require increased skill and training of both farmers and those responsible for assisting farmers in on-farm data collection and analyses.