U.S. agricultural practices create 58 percent of nitrous oxide in
the world, which is the third most prevalent greenhouse gas in the
atmosphere. Scientists believe nitrous oxide contributes to global
warming about 300 times more than carbon dioxide. New practices and
products have been introduced to address this issue, but farmers do
not have the time or profit margins to experiment with ideas that
may ultimately hurt the "bottom line." Now, researchers at the
University of Missouri have found methods to help farmers reduce
those emissions while also increasing corn grain production.
At the University of Missouri Greenley Research Center in northeast
Missouri, Kelly Nelson, a research agronomist and associate
professor in the MU Division of Plant Sciences, monitored fields of
poorly drained claypan soil that were planted with corn after
soybean. One field was "strip tilled" with nitrogen fertilizer
placed in a band in the soil, while another field was left untilled
with a surface application of nitrogen fertilizer. The research
team found that strip tillage and banded fertilizer significantly
reduced the amount of greenhouse gases emitted per bushel of corn
grain production, when compared to that of surface applied no-till
treatments.
Strip tillage is the practice of tilling a field in strips up to a
foot wide and eight to nine inches deep, rather than tilling the
entire field, so that crop residues can be left on the surface of
most of the field. By planting corn into those strips, and adding
fertilizer during the process, farmers can use less energy, reduce
soil erosion and conserve soil moisture in a large area of the
field. Additionally, the nitrogen stays deep in the soil, where it
less susceptible to environmental loss.
"This tells us that more efficient fertilizer use is needed to
maintain productivity and profitability," said Nelson. "We saw
grain yields increase, and this is important when it comes to
nitrous oxide emissions and the amount of food produced."
Peter Motavalli, associate professor in the MU Department of Soil,
Environmental and Atmospheric Sciences, directed the research
focused on measurements of soil nitrous oxide emissions and says
the results are another piece of information that can help farmers
select management options that may increase agricultural production
and economic returns while also reducing environmental impacts with
use of nitrogen fertilizer. The research was conducted during above
average rainfall growing seasons from 2008 to 2010 in
poorly-drained soils so the results of between 2.4 to 3.8 percent
cumulative loss of the applied fertilizer N as nitrous oxide N are
probably relatively high for conditions in Missouri.
"The main goal for our team has been to identify agricultural
practices that maintain or increase production while reducing the
environmental impact," Motavalli said. "There hasn't been much data
on greenhouse gas emissions for Missouri, and we hope to provide
information on how much nitrogen is being lost as nitrous oxide
with different agricultural practices so growers can make informed
choices depending on their farm operation and environmental
conditions."
Nelson, Motavalli, and Pat Nash, an MU graduate student, presented
the results of their three-year study, "Use of Strip Tillage to
Increase Corn Production and Reduce Soil Nitrous Oxide Emissions,"
at the national meetings of the American Society of Agronomy in
November and at the Missouri Crop Management Conference in
December.
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University of Missouri-Columbia: http://www.missouri.edu
Thanks to University of Missouri-Columbia for this article.