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United States Department of Agriculture

Agricultural Research Service


item Nelson, Nathan
item Mikkelsen, Robert

Submitted to: Journal of Natural Resources and Life Sciences Education
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2005
Publication Date: 12/1/2005
Citation: Nelson, N.O., Mikkelsen, R.L. 2005. Balancing the phosphorus budget of a swine farm: a case study. Journal of Natural Resources and Life Sciences Education. 34:90-95.

Interpretive Summary: Most of the meat produced in the U.S. is from animals grown on large-scale farms referred to as Confined Animal Feeding Operations (CAFOs). Physical concentration of animals on CAFOs results in large quantities of waste, which are generally applied to land surrounding the farm. Plant nutrients in the waste (such as phosphorus) can be washed into streams and rivers where it degrades water quality. Producers are expected to manage the waste, soil, and crops in a manner that minimizes nutrient loss. However, this is difficult when the quantity of nutrients entering the farm in animal feed exceeds the quantity leaving the farm in crops and meat. Regulatory, research, and cooperative extension agencies and must be aware of the complex factors influencing this problem in order to find environmentally and economically suitable solutions. This case highlights the decisions faced by a typical swine producer who is concerned about the accumulation of P on his farm in relation to new regulations for waste management. The data presented in this case are from personal interviews; soil and waste analysis; and farm records of waste application, crop production, and swine production. Influences of the animal production industry and environmental regulations on farm management are also presented. This case study should be used to teach college level students about soil fertility, crop management, waste management, animal science, non-point source pollution, nutrient cycling, and sustainable agricultural production on a farm scale. This case emphasizes multidisciplinary problem solving skills and the interconnections between local- and regional-scale agricultural production systems. Students should learn to identify the long-term impacts resulting from the changes in agricultural production systems and markets. Students can also extend their analysis to more complex issues of regulatory control of local agricultural practices.

Technical Abstract: Trends in animal production have moved the industry towards large confined animal feeding operations (CAFOs). These CAFOs concentrate large amounts of waste-based nutrients in relatively small areas, which increases the risk of nutrient loss to the surrounding environment. In response to water quality concerns, P-based waste application regulations are becoming more common. Mr. Pritchard is the owner and operator of a 4500-head swine farm located in an area of intensive animal production in North Carolina. He has noticed an increasing trend in the soil P concentrations in his waste application fields and realizes that he does not have enough land to apply anaerobic swine liquid based on crop P uptake. Mr. Pritchard is now faced with the dilemma of what to do to slow down the P accumulation in his soil. This case constructs a P budget for Mr. Pritchard's farm to examine ways of balancing on-farm nutrients. Students are encouraged to explore solutions related to animal nutrition, crop production, water quality, soil chemistry, and waste management. Furthermore, students should evaluate the appropriate role of government and industry in assisting Mr. Pritchard to protect the environment while remaining a profitable swine producer.

Last Modified: 06/25/2017
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