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Cost effective manure management

April 6, 2011, Madison, WI
– Recycling manure is an important practice, especially for large livestock
producers.
April 6, 2011, Madison, WI
– Recycling manure is an important practice, especially for large livestock
producers.

Manure can be used as
fertilizer to aid in crop production, aiding livestock producers that grow
their own feed crops. While manure does provide a rich nutrient source for
crops, it also can contribute to nutrient leaching and runoff. This can
contaminate the surrounding ecosystem and lead to eutrophication of waterways.
The desire for farmers to be able to recycle manure in an environmentally safe
manner while providing a sufficient supply of nutrients to their crops without
reducing profit, is an ongoing struggle.

Scientists at the USDA’s
Agricultural Research Service and Penn State used computer-simulated farms with
the support of field research to compare the environmental impact and economic
efficacy of using alternative manure application methods in farming systems.
The techniques and practices being evaluated included broadcast spreading with
and without incorporation by tillage, band application with soil aeration, and
shallow disk injection.

By comparing predicted
ammonia emissions, nitrate leaching, and phosphorus runoff losses with those
measured over four years of field trials, researchers were able to accurately
evaluate the model and find a good agreement. By simulating techniques that
would improve the incorporation of manure, the scientist noticed reductions in
ammonia emission and phosphorus runoff.

The study showed that
applying manure with a shallow disk injection device allowed the lowest
nutrient loss without negatively impacting the farm’s profitability compared
with the other techniques being studied. Band application of manure along with
the use of soil aeration was less environmentally beneficial. Moreover the
increased cost of production was usually greater than the overall economic
benefit.

“Shallow injection of
manure appears to be the best option for reducing nutrient losses to the
environment,” said Al Rotz, one of the USDA-ARS scientists who conducted the
study. “Although this additional equipment and the management required increase
the cost of manure handling, the annual improvement in nutrient use can often
offset this cost and in some cases may even improve farm profitability.”

Results from the study
were published in the March/April 2011 issue of the Journal of Environmental
Quality.

Research is ongoing in
Pennsylvania and other locations in the mid Atlantic area to further evaluate
different methods for subsurface injection of manure in both liquid and solid
forms. Refinement and adoption of this manure application technique is one of
many potential strategies for reducing nutrient runoff into the Chesapeake Bay.
Reduction in this nutrient loading is needed to help clean and improve the
aquatic life in the Bay.

The full article is
available for no charge for 30 days following the date of this summary. View
the abstract at www.agronomy.org/publications/jeq/abstracts/40/2/438.