Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
5/14/01
Contacts:
John Creswell, Nutrient Management Education Project, (515)
727-0656, creswell@iastate.edu
Elaine Edwards, Continuing Education and Communication
Services, (515) 294-5168, eedwards@iastate.edu
Late Spring Nitrogen Test Can Help Manage Nitrogen Applications
AMES, Iowa -- The late spring test for soil nitrate is a tool designed to assess the nitrogen (N) needs of corn during the early growing season. It is especially useful with manured fields, where test results can provide reassurance of N being available for corn use.
"If you didn't get adequate N applied preplant or had losses occur, the symptoms of N deficiency in corn might not be visible until it's too late to correct," said John Creswell, nutrient management education coordinator for Iowa State University (ISU) Extension. "The late spring nitrogen test can help you determine the in-season N needs of corn."
The amount of yield recovery depends on the crop stage when N deficiency occurs and the severity of deficiency. "By using the late spring nitrogen test to correct N deficiencies early in the season, the corn yield potential isn't limited," Creswell said.
To sample for the late spring nitrogen test, collect soil cores from the top 12 inches of soil, when the corn is between 6 and 12 inches tall. ISU Extension publication PM 1714, Nitrogen Fertilizer Recommendations for Corn in Iowa, gives detailed information on how to take a late spring nitrogen test and handle the samples.
"Using this test can help corn growers limit preseason applications of N and apply N strategically - only where and when it is needed," Creswell said. "This approach means that excess N levels can be avoided, thereby increasing profits for the corn grower and improving water quality for everyone."
For more information on the late spring nitrogen test, contact your county ISU Extension office for a copy of PM 1714. PM 1714 also can be downloaded from the ISU Continuing Education and Communication Services Extension Publication home page at http://www.extension.iastate.edu/Publications/PM1714.pdf.
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