Finding solutions: cover crops
by Lucia Levers, Water Resources Center Research Associate
Nitrogen pollution. The term is inextricably linked with growing corn: here in Minnesota, and all along the Mississippi river basin. The consequences of nitrogen runoff are becoming more well-known—algal blooms and the Dead Zone in the
Gulf of Mexico are now part of the popular lexicon. In fact, USA Today, has run articles on both topics—the latest of which focuses on a scientific study describing how long term changes in agricultural practices will be necessary to bring the Dead Zone into compliance—and even then, it would take many years for all the excess nitrogen currently in the system to work its way out.
But, there is no need to let tears “runoff”: community members, agriculturists, and researchers are working on ways to reduce agricultural nitrogen pollution, without severely impacting the agricultural industry.
Here at the Water Resources Center, we are looking at cover crops to do just that.
To understand why cover crops are a way to combat nitrogen, one must understand a bit about how a typical corn field contributes to nitrogen pollution. Corn is harvested in the fall, nitrogen fertilizer is applied for next year’s young plants, then the fields lay bare until spring planting. Nitrogen pollution leaches out the system over the winter and into our waterways. By planting a cover crop after the corn harvest, nitrogen is effectively stored in a plant over winter. This reduces nitrogen pollution, but also has a number of other benefits such as decreasing erosion and sedimentation, and increasing biodiversity, soil organic matter, and biological activity.
Sounds fantastic, but unfortunately, as pointed out in this Star Tribune article, cover crops are not free for the farmer. And while they may reduce fertilizer needed, providing a monetary benefit, the rest of their budgetary effects are costs.
Since providing environmental benefits help everyone, including the creatures of the Gulf of Mexico, here at the WRC we have been researching subsidies to encourage cover crop adoption. A subsidy program would help alleviate any cost concerns that corn farmers may have. With the Minnesota Board of Water and Soil Resources, we collected data from farmers to assess the types and amounts of subsidies that would spur cover crop adoption. Not all land, nor farmers are alike, so it is important to discover both where cover crops would be most effective, and with whom. Additionally, as discussed in the previous Minnegram, we continue to work with other University of Minnesota researchers to answer questions about cover crop species, methods, and effectiveness.
These programs may become particularly important with nitrogen fertilizer application limitations, as outlined by Governor Dayton’s plan, expected to be finalized this December.