Just because corn and soybeans have been harvested doesn’t mean it’s time for no-tillers to stop worrying about nutrient management.
The majority of drain flow in the Midwestern Corn Belt occurs in the fallow period between October and April. That’s when most water leaks out the bottom of the root zone — regardless of whether a field has tile, says Eileen Kladivko.
But wisely chosen cover crops may help no-tillers keep nitrogen from washing away and possibly save it for the following cash crop, the Purdue University soil physicist told attendees at the 2013 National No-Tillage Conference.
Kladivko says nitrogen-loss issues occur in the fallow period because there is often excess precipitation and no crop growing to take up the moisture. Drain flow can carry away residual nitrogen left in the soil profile from the prior crop, she says.
“The nitrogen that farmers lose is lost primarily in the winter, and this applies to everybody — whether they apply fertilizer in the spring, summer or fall,” she says.
There are several species of cover crops that can scavenge extra nitrogen and keep it in the soil profile.
“The rationale of cover crops as nitrogen scavengers and as a water-quality benefit is that something is being grown in the fall and early winter to take up some of that nitrogen. And if it doesn’t winterkill, it will do that again in the spring,” Kladivko says. “So cover crops reduce the amount of nitrogen that can be leached out the…