Know Your Nitrogen Carryover

Sampling soils could save you money.

Published on: Sep 12, 2006

Farmers whose yields have been thinned by drought conditions in recent years may find something valuable in their soil, but they'll have to dig to find it, says Dave Mengel, Kansas State University Research and Extension soil fertility specialist.

"Producers should consider taking profile soil samples to test for available nitrogen in their soils," Mengel says. "We're finding that many fields have high carryover levels of available nitrogen, and this reduces the amount of nitrogen that needs to be applied for their wheat crop this fall, sometimes by up to $20 per acre or more."

A profile nitrogen test should be taken to a depth of two feet, Mengel added. The samples must be taken before any nitrogen fertilizer is applied and before the crop is planted. If the samples are pulled after fertilizer has been applied, it will give misleading results, he explains.

"These are all based upon a 24-inch deep soil sample where I took 12-15 probes per field," says Dale Ladd, Kansas State Research and Extension agent in McPherson County. "Sampling deep is hard work, and you may want to have a consultant or fieldman do the job. But it will be well worth the effort to have the information," Ladd says.