Field Notes: Making the most of cover crops

Oct 26, 2012

This is the latest installment of Harvest Public Media’s Field Notes, in which reporters talk to newsmakers and experts about important issues related to food production.

For this edition of Field Notes, Harvest Public Media's Amy Mayer spoke with Tom Kaspar, a plant physiologist at the National Lab for Agriculture and the Environment, about the importance of cover crops in how our food is grown.

We know that farmers grow our food. But often we think about the food production process in simple terms: farmers plant seeds, food grows, then it’s harvested. Those of us far removed from the growing stage tend to think of our land as a renewable resource – we keep planting and it keeps giving.

But soil, even the most productive soil, isn’t just a food ATM. It has to be taken care of and worked relentlessly. One way farmers can help preserve and strengthen the soil they work is by planting cover crops and a growing number of Midwest farmers are turning to cover crops like oats and winter rye in order to protect and improve the soil their livelihood depends on.

A cover crop is something that’s planted late in the season and lives in the soil when the land would otherwise be barren. Cover crops can help prevent erosion and improve soil nutrients by living on the land between harvest and planting season. But they’ll cost a farmer in time and seeds and the benefits can be a long time off.

Most cover crops don’t even make a farmer money directly. But, Kaspar says, they can be vital for farmers depending on the land.

“Certainly, areas that are susceptible to erosion are going to be the big things that cover crops would immediately come to mind,” Kaspar said. “I know farmers in western Iowa in the Loess Hills – sloping land – not all farmers are interested but there are those out there that said, ‘Yeah, if I’m going to farm these slopes I need to do something like that.’”

Cover crops are most often planted in the fall and help farmers preserve the nitrogen in their soil. More nitrogen preserved means farmers need to add less nitrogen in the spring via fertilizer.

“The cover crop acts as kind of a buffer on that system, to prevent [organic forms of nitrogen] from being lost, make them more available during the time when the main crop plants need them,” Kaspar said.

If better soil is more productive soil, cover crops may be vital.