Released Feb. 25, 2008
ST. PAUL, Minn. — Scientists are solving the mysteries behind Iron Deficiency Chlorosis.
The condition, which causes yellowing of the soybean plant, was providing an important clue all along.
In contrast to yellowing soybean plants, soybeans planted in tractor or planter wheel tracks stayed green.
George Rehm, University of Minnesota Extension soil scientist, began talking about the phenomenon of the "green tire tracks" about three years ago. He wanted to find out why this occurred.
Rehm and his colleagues determined that compaction in the wheel tracks made nitrogen less available to the soybean plant.
They learned that IDC is a condition related to high levels of nitrate-nitrogen in soils that already have high levels of salts and free calcium carbonate. The high levels of nitrate-nitrogen appear to interfere with the metabolism of iron in the plant in the formation of the chlorophyll molecule.
There are a couple of ways to fight this yield-robbing condition. Seed companies have improved varieties to the point where damage from IDC is less severe. Rehm suggests another method for reducing IDC on the AgBuzz.com blog page, http://www.agbuzz.com. Growing an inexpensive competition crop along with soybeans makes less nitrate-nitrogen available to the soybean plant and decreases IDC.
In 2006 and 2007, research directed by John Lamb, University of Minnesota Extension soil scientist, recorded a reduction in IDC when oats were planted with soybeans, and then the oats were killed with a glyphosate treatment. In addition to less IDC, the soybeans had higher yields.
Planting a competitive crop with soybeans carries risks, Rehm said. The oats use moisture, and in a dry year, reduced soil moisture could have a negative impact on soybean yield. The timing of the glyphosate application is also very important.
With continued varietal improvements and a better understanding of the causes of IDC, farmers have new tools that can help in the management of this significant soybean condition.
You can read more about this research at AgBuzz.com.
The AgBuzz.com blog is a cooperative effort of University of Minnesota Extension and Minnesota Farm Guide.
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http://www.extension.umn.edu/extensionnews/2008/agbuzz022508.html
Contacts: Julie Christensen, (612) 626-4077, reuve007@umn.edu
Andrea Johnson, (320) 289-2256, andreaj@mchsi.com
