On a 33-foot tower in Doug Wulf's cornfield near Morris, Minn., ARS scientists mounted sensors to monitor the flow of carbon dioxide and water in and out of the soil. (Photos courtesy Chris Wente; not available at 300 dpi)

Prairie Towers Watch Carbon and Water Losses from Cornfields

By Don Comis
April 29, 2005

A pair of 33-foot towers flanking a road that divides two of Doug Wulf's cornfields puzzles drivers south of Morris in western Minnesota. The towers hold instruments that monitor wind, carbon dioxide and water vapor year-round, 24 hours a day. The instruments have to be moved upwards as the corn grows each season, so they always stay about six feet above the corn tassels.

Soil scientist Don Reicosky and research technician Chris Wente from the Agricultural Research Service's (ARS) North Central Soil Conservation Research Laboratory at Morris work on the experiment with John Baker and colleagues from the ARS Soil and Water Management Research Unit at St. Paul. The experiment is monitoring Wulf's attempt to boost his corn yields to 400 bushels of corn per acre mainly by applying higher amounts of manure and fertilizer. Wulf is also using deeper plowing and denser stands of corn.

Wulf and the scientists want to check for manure and fertilizer losses and their effects on the environment, as well as effects of deep tilling, and the corn's increased use of soil water.

Manure and tillage can release carbon dioxide, methane and nitrous oxide--all greenhouse gases associated with potential global warming--and can also increase nutrient losses in rain runoff. This spring the scientists will begin testing water from field drainage pipes for nitrogen and phosphorus. Eventually, they'll measure emissions of carbon dioxide, methane and nitrous oxide with ground-based chambers as well as their meteorological instruments.

The research is timely as large dairy confinement operations expand in the area as well as nationwide. If this manure can be converted into nutrients that grow more corn, without harm to the environment, then it would be a double benefit to farmers. Dairy farmers usually have no other way to get rid of the manure than to apply it on nearby fields to fertilize corn or other crops.

ARS is the U.S. Department of Agriculture's chief scientific research agency.