U.S. Environmental Protection Agency
National Cattlemen’s Beef Association
U.S. Poultry & Egg Association
United Egg Producers
National Pork Producers Council
National Milk Producers Federation
Beneficial Uses of Manure and Environmental Protection
August 2015
The Components of Manure
The value of manure is found in its nutrients, organic matter, solids, energy potential, and fiber. A variety of products and byproducts can be generated using manure. EPA, NCBA, USPOULTRY, UEP, NPPC, and NMPF encourage the environmentally sound use of manure. Its constituents can be used as a resource for crop production, improvement of soil quality, and other purposes, while leading to water quality improvements.
Throughout history, people who raise livestock and poultry have used manure as a fertilizer, soil amendment, energy source, and even construction material. Manure contains many useful, recyclable components, including nutrients, organic matter, solids, energy, and fiber. With today’s science and technology,
we can use manure more efficiently and in more ways than ever. These techniques can protect water and air quality, and reduce greenhouse gases. When managed improperly manure can harm the environment, but when properly managed it can serve as a valuable, renewable resource.
Turning Manure into Valuable Products
Nutrients
Manure contains nitrogen, phosphorus, and other nutrients that plants need to grow. Farmers can often save money by properly using manure as a fertilizer. Farmers can also sell manure or manure products to gardeners, landscapers, golf courses, and others who use nutrients to grow plants.
Manure can be land-applied in its raw form, or after processing (for example, composting, pelletizing, nutrient extraction). Just like other fertilizer sources, as long as the manure is applied from the right source, at the right rate and time, using the right methods, and in the right place, manure nutrients can be recycled safely through agricultural systems. Land application of manure should be guided by a nutrient management plan (NMP) that outlines how to balance crop needs with manure nutrient concentrations. The NMP includes specifications for manureapplication based on soil and geographical conditions in order to avoid over-application, prevent runoff, and protect water quality. Proper use of manure as a fertilizer minimizes nutrient pollution to water resources and helps build healthy soils.
Manure nutrients can also be used to grow worms, insect larvae, algae, or other living organisms. Through “biomass conversion,” these organisms transfer manure nutrients to their bodies or castings, which can then be harvested and used as fertilizer, animal feeds, or soil amendments.
Organic Matter
Adding manure to soils is an excellent way to increase soil
organic matter. Soil organic matter contributes to overall soil
health - the soil’s ability and sustainability to function as a living
ecosystem. In addition to slowly releasing plant nutrients over
t
ime, organic matter
improves soil structure
and the soil’s ability to
hold water. Healthier
soils improve crop
yields and reduce soil
loss from both wind
and water erosion,
and protect water
quality by reducing
contaminated runoff.
Land managers can
increase soil organic
matter by applying raw
manure or a manure
product like compost,
pellets, or biochar - a
product of manure combustion. Manure should be utilized
appropriately, as noted in the previous section.
Solids
Manure begins as mostly water. Different types of manure
can contain from 8 to
26 percent solids. By
separating the liquid and
solid portions of manure,
the solids can be used
for other purposes. Many
dairy farms use separated
manure solids for bedding.
This can save farmers up to
$50 per cow every year -
savings that can add up
for dairy farmers milking
hundreds of cows!
Energy
Manure contains a lot of carbon and other elements that can be used to generate different types of biofuels. Anaerobic digestion is a technology that uses microbes to process manure into biogas. Biogas can be used to generate heat or electricity for use on the farm or sale to the local power grid. Thermal processes can produce liquid bio-oil fuels, including biodiesel, and useful byproducts like biochar. Bio-oils can be used for heating or generating electricity. Biodiesel can be used just like petroleum diesel. Gasification can also be used to convert manure to syngas, a synthetic gas fuel that can power engines, turbines, and fuel cells. Using manure to generate biofuels reduces our reliance on non-renewable fossil fuels. In addition, farmers can save money when biofuels are used on the farm.
Fiber
Manure contains a great deal of fiber. Some of the fiber is from undigested animal feed and some is from straw, sawdust, or other bedding that gets mixed in with the manure. Manure fiber has been used to produce a number of specialty consumer products like plant growth medium (similar to peat moss), seed starter pots, fertilizer garden sculptures, paper, and building materials. Consumer products help turn manure from a potential environmental liability to a commodity.