Studying Fertilizers to Cut Greenhouse Gases
November 17, 2009
Agricultural Research Service (ARS)
scientists have found that using alternative types of fertilizers can cut back
on greenhouse gas emissions, at least in one part of the country. They are
currently examining whether the alternatives offer similar benefits nationwide.
Nitrogen fertilizers are often a necessity for ensuring sufficient crop
yields, but their use leads to release of nitrous oxide, a major greenhouse
gas, into the atmosphere. Fertilizer use is one reason an estimated 78 percent
of the nation's nitrous oxide emissions come from agriculture, according to
Halvorson, a soil scientist at the ARS
Plant Nutrient Research Laboratory in Fort Collins, Colo.
Halvorson compared nitrous oxide emissions from corn fields treated with
either a conventional nitrogen fertilizer (urea) or either of two specially
formulated urea fertilizersone with "controlled release"
polymer-coated pellets, and the other with inhibitors added to
"stabilize" the urea to keep more of it in the soil as ammonium for a
In a two-year experiment at Fort Collins, he collected the emissions using
static vented chambers, similar to small "pillbox" structures placed
over the soil. He chose a no-till cropping system because it's known to reduce
carbon dioxide emissions. He found that the controlled-release fertilizer cut
nitrous oxide emissions by a third, and that the stabilized fertilizer cut them
almost in half.
Halvorson's results are so far limited to the irrigated fields and cool,
semi-arid conditions in and around Fort Collins. But nitrous oxide releases are
the result of a complex interplay of conditions that vary from one area to the
next, such as soil water content, soil temperatures, soil types, microbial
activity, climactic conditions and rainfall patterns. So Halvorson is expanding
the study, with support from the fertilizer industry and cooperation of other
ARS locations, to see how the fertilizers respond at seven sites around the
The research supports the U.S. Department of
Agriculture (USDA) priority of responding to climate change.
more about ARS climate change research in the November/December 2009 issue
of Agricultural Research magazine.
ARS is USDA's principal intramural scientific research agency.