
New Equations Reduce Chance of Water
Pollution From Dairy ManureBy Judy
McBride July 29, 1997 New, simple-to-use equations estimate
how much manure a specific dairy herd produces. Developed by scientists with
USDAs Agricultural Research Service,
these equations will help agricultural engineers design waste storage systems
to prevent pollution of streams and rivers with nitrogen and other nutrients in
the manure. More jurisdictions now monitor water quality and hold dairy farmers
accountable for polluting waterways. So farmers are storing manure in pits and
other holding facilities until it can be applied to fields or recycled as
compost. The trouble is, a herd may produce more manure than the holding
facilities are designed to contain--especially with high milk-producing cows
that eat more. The manure production research at ARS Beltsville (Md.) Agricultural
Research Center is part of a broad effort at the center to improve management
of manure nutrients by studying their complete cycle--from the soil into the
forage into the cow and back to the soil. A scientist at ARS
U.S. Dairy Forage Research Centerin Madison, Wis., collaborated on the equations. Traditional methods for designing manure-storage facilities use an average
value for manure output, gleaned from many scientific observations. The new ARS
equations make for a more accurate estimate by plugging in the farmers
own herd statistics. These include the animals body weight, milk
production and composition, feed makeup and number of lactating cows. Many farmers use manure for fertilizer to reduce spending on commercial
nitrogen fertilizer. But some nitrogen in fresh manure vaporizes before it can
reach the field. The new equations estimate the manures initial nitrogen
content--encouraging design of storage systems that save more of the nitrogen
and thus help farmers save more on fertilizer outlays. The new equations also
can give policy makers a more accurate reading on nitrogen escaping into the
atmosphere from dairy farms. Scientific contact: Victor A. Wilkerson, ARS
Nutrient Conservation
and Metabolism Laboratory, Beltsville
Agricultural Research Center, Beltsville, Md., phone, (301) 504-8620, fax
504-8744, [email protected] U.S. Department of Agriculture | |