Manure Manager

Features Applications Beef
Put more nitrogen into milk, not manure


June 3, 2010
By Manure Manager

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May
31, 2010 – The more efficient dairy farmers are in managing nitrogen, the more
milk their cows will produce and the less nitrogen will be channeled into
manure and urine, according a study by Agricultural Research Service (ARS)
scientists and cooperators.
May
31, 2010 – The more efficient dairy farmers are in managing nitrogen, the more
milk their cows will produce and the less nitrogen will be channeled into
manure and urine, according a study by Agricultural Research Service (ARS)
scientists and cooperators.

ARS
soil scientist J. Mark Powell at the U.S. Dairy Forage Research Center in
Madison, WI, worked with ARS agricultural engineer Clarence Rotz at the ARS
Pasture Systems and Watershed Management Research Unit
in University Park, PA,
and Australian colleagues to calculate nitrogen use efficiency ratings to guide
dairy farmers.

These
new efficiency ratings could help dairy farmers make better use of their
nitrogen in the face of escalating costs and increasing nutrient regulation.
Farmers feed nitrogen in the form of crude protein to their cows, and apply
manure and nitrogen fertilizer to grow crops and pasture for cows to eat and
convert to milk.

The
scientists found that only about 20 to 35 percent of the nitrogen fed to dairy
cows is converted into milk. They also discovered that 16 to 77 percent of the
nitrogen in manure or fertilizer is necessary for grass and other pasture
plants. And their study showed that between 8 and 64 percent of all the
nitrogen applied to typical commercial dairy farms is converted into farm
products.

They
determined the whole farm nitrogen use efficiency by applying the ARS-developed
Integrated Farming System Model on two typical dairy farm types in Wisconsin.
They used the model to quantify the effects of numbers of cows per acre and
manure nitrogen credits (reducing fertilizer nitrogen applications when manure
is applied) on nitrogen use, farm profitability, and pathways of nitrogen loss.

The
wide ranges in nitrogen use efficiency point to the fact that there is
significant room for improvement by using various practices that improve
nitrogen use, profits, and the environment. Nitrogen use efficiency formulas
can be used as tools to promote practices that maximize nitrogen use so that
nitrogen does not leave farms to pollute waterways and ground water and
negatively impact air quality.

From
these tools, which are effectively a nitrogen efficiency audit, may come
recommendations to dairy farmers, consultants, and policy makers.

This
research was published in the Environmental Science and Policy Journal.


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