Time to Decide About Sidedressing Nitrogen

Weekly crop survey shows Iowa has 98% of corn planted, 87% of soybeans.

Published on: May 30, 2007

The weekly weather and crop survey released May 29 by Iowa Ag Statistics Service shows that Iowa had 98% of the state's corn planted and 87% of the soybeans planted by May 27. The corn planting progress for 2007 is equal to the five-year average and only three days behind last year's 99%.

Over 86% of the state's corn crop is now emerged, one day behind last year's 89% and one day ahead of the five-year average of 85%. Corn condition is across the state is 0% very poor, 3% poor, 17% fair, 59% good and 21% excellent.

The survey shows 87% of the 2007 soybean acreage planted in Iowa by May 27, and the crop is now over 47% emerged. Soybean planting is two days behind last year's 91% but two days ahead of the five-year average of 84%. Soybean emergence is 3% behind last year but 5% ahead of the five-year average. Soybean condition currently rates 2% poor, 20% fair, 62% good and 16% excellent.

First cutting of alfalfa hay is underway

The first cutting of alfalfa hay is underway in Iowa with 10% complete as of May 27. Last year at this time 36% of the first-cutting alfalfa had been harvested. The five-year average is 16% complete. All hay condition is 3% very poor, 10% poor, 31% fair, 47% good and 9% excellent. Pasture condition is rated 1% very poor, 5% poor, 27% fair, 51% good and 16% excellent. Livestock condition is good.

Guidelines for sidedressing N on corn

"Some farmers are starting to sidedress nitrogen on corn this week," says Mark Licht, Iowa State University Extension crop specialist based at Carroll in western Iowa. "Sidedressing is a good nitrogen management strategy because you apply it closer to the time when the corn plant actually uses the most nitrogen. The N doesn't have the potential to be lost like fall-applied or early spring-applied N does, especially with the wet conditions we've been experiencing this spring."

If you haven't applied any nitrogen at all for your corn crop this year, then sidedressing is a must. If you have applied only a portion of the N needed for the corn crop, then you'll want to think about using the late-spring soil nitrate test to determine how much additional nitrogen you need to apply, says Licht.

Soil samples for this test should be taken when corn is in the V4 to V6 growth stage (corresponds to 6 to 12 inches tall). Licht says you should take a single soil sample of 16 to 24 cores per 10 acres to a 12-inch depth. Cores should be taken in sets of eight across the corn rows. After samples have been collected they should be kept cool and sent to a lab as soon as possible for testing. Visit the ISU ICM newsletter of May 14 for more directions www.ipm.iastate.edu/ipm/icm.