|Powell, J Mark|
Submitted to: Nutrient Cycling in Agroecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2008
Publication Date: 3/18/2008
Citation: Powell, J.M., Li, Y., Wu, Z., Broderick, G.A., Holmes, B.J. 2008. Rapid Assessment of Feed and Manure Management on Dairy Farms in Wisconsin, USA and Shandong Province, China. Nutrient Cycling in Agroecosystems. 82:107-115. Interpretive Summary: Dairy farms transform feed nitrogen (N) and phosphorus (P) into milk, and manure N and P are land-applied to crops used for feed. Much is known about relationships between feed consumption and milk production, and between manure applications and crop yields under experimental conditions. Relatively little information is available, however, on feed and manure management under producer conditions, and where improvements in nutrient use can be made to improve profitability and environmental performance of dairy operations. Information was collected on cow diets, milk production and manure management on 41 dairy farms in Wisconsin USA and 2 dairy farms in Shandong Provence, China using a rapid survey approach. The range of calculated feed N and P use efficiencies (amount of feed N and P transformed into milk) corresponded to general industry levels, but were below experimental levels. Comparisons of manure N excretions calculated from the difference in feed N intake and milk N secretions determined from the survey data, to manure N excretions derived from an extensive data base of dairy cattle in the U.S. indicated reliable data was collected on relationships between feed, milk, and manure-N. Relatively short (2-3h per farm), face-to-face interviews with farmers were able to provide accurate 'snap-shots' of general feed and manure management practices on diverse dairy farm types. This survey approach can be used by researchers, extension staff, dairy producers, and nutrient management consultants to monitor overall nutrient use on dairy farms and determine where improvements can be made.
Technical Abstract: A basic function of dairy farming is to transform feed nutrients into milk to generate an economic return. Dairy farmers cannot afford, however, to focus solely on profitable milk production. They are increasingly being held accountable for manure management and associated negative environmental impacts. Whereas much is known about relationships between feed, milk and manure production under experimental conditions, relatively little information is available on feed and manure management under producer conditions, and how this may impact the environmental performance of their dairy farms. The purpose of this study was to evaluate information collected on cow diets, milk production and manure management during rapid (2-3 h) surveys on forty-one dairy farms in Wisconsin, USA and two dairy farms in Shandong Provence, China. On-farm data was compared for feed-milk-manure relationships established under experimental conditions and elsewhere. For dairy farms in both regions, average estimates of feed nitrogen (N) intake were only slightly more than calculated N outputs in milk and manure, indicating accurate information on feed dry matter (DM) and N intake. On-farm feed N use (FNUE) and feed phosphorus use (FPUE) efficiencies were below efficiencies determined under experimental conditions. The range of values calculated from the on-farm data provided a 'snap-shot' of FNUE and FPUE across a fairly wide range of feeding practices on confinement dairy farms. Comparisons of on-farm manure N excretions calculated from the difference in feed N intake and milk N secretions, to those calculated derived from an algorithm based on an extensive US data base further indicated accurate relationships between feed-milk-manure-N. In Shandong, both farms appeared to manage manure effectively, given the limitations of the facilities. Approximately 55% of manure N and 90% of manure P excreted by the dairy herd on Shandong dairy farms was apparently collected and applied to wheat fields and vegetable gardens. Relatively short, face-to-face interviews with farmers were able to provide fairly accurate, general 'snap-shots' of feed and manure management practices on Wisconsin and Shandong dairy farms.