Manure Management

Manure management—how manure is captured, stored, treated, and used—has important implications for farm productivity and the environment. When applied according to the agronomic needs of crops, manure can improve productivity by reducing the need for commercial fertilizer. Farmers who install an anaerobic digester on their livestock operations can use manure to produce a biogas that can be burned to generate electricity. Digesters can also reduce greenhouse gas emissions from manure storage and handling. Manure management can affect water quality. The over-application of manure nutrients (nitrogen, phosphorous) to cropland can increase the risk that these nutrients flow into surface water. Agriculture is a major source of the nutrient pollution causing hypoxic "dead" zones in many areas of the country, including the Chesapeake Bay, Gulf of Mexico and the Great Lakes. ERS research examines how agricultural and environmental policies combined with market forces and the changing structure of animal agriculture influence manure management decisions, farm income and environmental outcomes.

• Improving manure management. Developing new uses and markets for manure may result in both economic and environmental benefits. The ERS report, Increasing the Value of Animal Manure for Farmers (AP-109, March 2023), uses data from the USDA Agricultural Resource Management Survey (ARMS) to describe current manure production, handling, storage, and use. An extensive review of manure-related research describes existing and emerging technologies that have the potential to increase the value of manure or reduce manure management costs.

• Options to reduce agricultural pollutants in the Chesapeake Bay. In 2010, a Total Maximum Daily Load (TMDL) was established for the Chesapeake Bay, setting limits on emissions of nitrogen, phosphorus, and sediment necessary to reverse declines in the Bay’s quality. Agriculture is the largest source of nutrients and sediment in the watershed. The cost of achieving water quality goals depends heavily on which policies are selected and how they are implemented. The ERS report, An Economic Assessment of Policy Options To Reduce Agricultural Pollutants in the Chesapeake Bay (ERR-166, June 2014), assesses several policy instruments for achieving the TMDL goals to identify which policy design features lead to a more cost-effective solution.

• Greenhouse gas emissions and the adoption of digesters on livestock operations. Methane digesters—biogas recovery systems that use methane from manure to generate electricity—have not been widely adopted in the United States because costs have exceeded benefits to operators. Burning methane in a digester reduces greenhouse gas emissions from manure management. ERS research, Climate Change Policy and the Adoption of Methane Digesters on Livestock Operations (ERR-111, February 2011), considers how a policy or program that pays producers for these emission reductions—through a carbon offset market or directly with payments—could increase the number of livestock producers who would profit from adopting a methane digester.

• Changes in hog manure management. ERS research, Trends and Developments in Hog Manure Management: 1998-2009 (EIB-81, September 2011), uses data collected in three national surveys of hog farmers to examine changes in how hog farms manage and store manure. The authors examine how the use of nutrient management plans and practices such as controlled manure application rates vary with scale of production and how these practices changed over the study period. Findings further suggest that environmental policy has influenced conservation-compatible manure management practices.