Agricultural Engineering News, Issues, and Research: Animal Agriculture and the Environment

Agricultural Engineering Specialist
WVU Extension Service

The following summaries are compiled from recent publications, research articles, and presented papers. They are intended to inform readers of agricultural engineering developments and related issues of interest to West Virginians. These brief summaries are not comprehensive; they do not represent all data, results, and conclusions of the articles. Readers are encouraged to obtain the complete publications for more information. While it is believed that the sources are reliable, caution is urged in application of this information.

Animal Agriculture and the Environment: Nutrients, Pathogens, and Community Relations

The Animal Agriculture and the Environment Conference, held Dec.11-13, 1996 in Rochester, New York, addressed many issues faced by dairy, poultry, swine, and beef producers in the northeastern United States and Canada. The proceedings are available from Northest Regional Agricultural Engineering Service (NRAES) (NRAES-96) for $30. Included are 33 papers divided into six categories: environmental concerns, protecting the environment, land application, animal management, considerations in public policy, and cost to the farmer. The proceedings will be of interest to producers and their advisers, community officials and their consultants, state/province regulatory agencies and legislatures, cooperative extension and university educators, crop consultants, rural land owners, soil and water conservation district staff, federal government staff, and watershed managers.

Three of the papers presented at the conference are highlighted below.

Environmental Protection Can Save the Farm Money

Best Management Practices (BMPs) commonly associated with nutrient management can save money for many farmers. Some sources of savings include "legume credits," "manure credits," and soil testing. "Legume credits" represent nitrogen carry-over from legumes in rotational cropping. By taking a nitrogen credit for the carry-over in a nutrient management program, a producer can reduce fertilizer costs. Similarly, nutrients contained in applied manure can be substituted for commercial fertilizers. Fractions of these nutrients are carried over from year to year, so previous years' applications contribute to this credit. Manure testing services have facilitated more accurate accounting of nutrient availability from manure. Field-specific soil testing is recommended to optimize use of fertilizers and manures. Dr. Steinhilber, coordinator of the Nutrient Management Program at the University of Maryland Cooperative Extension Service, cautions nutrient management advisers that nutrient management BMPs are not guaranteed to save money for all producers. Apparently, however, the greatest cost savings are likely to be incurred by below-average nutrient managers.

Patricia M. Steinhilber. 1996. "Environmental Protection Can Save the Farm Money." In: Proceedings from the Animal Agriculture and the Environment North American Conference. NRAES-96. Northeast Regional Agricultural Engineering Service, Cornell, NY.

Improving Nutrient Cycling in Animal Agriculture Systems

According to Meisinger and Thompson (1996) at the USDA-Agricultural Research Service (ARS) Natural Resources Institute in Beltsville, Maryland, "Constructing nutrient balances that characterize nutrient inputs, exports, and changes in nutrients stored within the soil-crop-animal system (is) a fundamental approach for effective nutrient management. A whole-farm nutrient balance provides the basis for a well-designed nutrient management plan which assures an adequate and sustained supply of high-quality feed, supports high nutrient recycling, and minimizes environmental impacts."

Meisinger and Thompson discuss the main steps in constructing a nutrient budget, including: defining the system and subsystems; documenting nutrient inputs and outputs; evaluating potential changes (such as nutrient losses) in storage within the system; and identifying surplus and/or deficit areas and potential sites of accumulation and/or depletion. The authors recommend manure testing, on-farm quick nutrient tests, soil sampling to monitor nutrient status, timely application of manure to coincide with crop demand, immediate incorporation of applied manure into the soil, and more efficient ration formulation which maximizes use of farm-grown feeds.

J.J. Meisinger and R.B. Thompson. 1996. "Improving Nutrient Cycling in Animal Agriculture Systems." In: Proceedings from the Animal Agriculture and the Environment North American Conference. NRAES-96. Northeast Regional Agricultural Engineering Service, Cornell, NY.

Potential Pathogens in Manure

Manure (including feces, urine, and possibly bedding, waste feed, and water) contains microbial organisms, including potential pathogens (viruses, bacteria, and parasites capable of causing infection or disease in animals or humans). In order for pathogenic organisms to be spread in manure, they must be present in sufficient number to be infectious, multiply in the environment, or survive manure processing and storage conditions long enough to accumulate to infectious population levels.

High temperatures achieved during ensiling, aerobic composting, and mesophilic anaerobic digestion will kill most pathogens within days. For example, bovine parvovirus survives 20 to 43 days in manure stored in anaerobic pits at 61 oF. Survival of the virus is decreased to four to eight days at 95 oF (mesophilic anaerobic digestion conditions), and to less than one day at 131 oF (thermophilic anaerobic digestion or aerobic composting conditions). Escherichia coli populations held in mesophilic anaerobic digestion conditions at 95 oF are decreased by 90% in 0.8 to 1.5 days.

Other environmental factors that limit activity or survival of some pathogenic organisms are sunlight, moisture, freezing, high or low pH, oxygen levels, and chemical compounds. Salmonella survival is decreased by aerobic (oxygen available) storage, low pH, and higher temperatures. Listeria monocytogenes survival is decreased by exposure to sunlight, low pH (<4.0), and higher temperatures.

This article addresses viruses, bacteria, and parasites that may be present in manure. It also addresses consequences of infection by these pathogens in animals and humans. The authors are on faculty at the College of Veterinary Medicine at Cornell University.

Susan M. Stehman, Christine Rossiter, Patrick McDonough, and Susan Wade. 1996. "Potential Pathogens in Manure." In: Proceedings from the Animal Agriculture and the Environment North American Conference. NRAES-96. Northeast Regional Agricultural Engineering Service, Cornell, NY.