Cover crops aren’t a new idea. They’ve been around for a long time, but they haven’t caught on as a widespread conservation technique. There are a few reasons for this.
“We all know about the benefits of cover crops,” said Alex Garcia y Garcia assistant professor/cropping systems, Department of Agronomy and Plant Genetics at the University of Minnesota’s Southwest Research and Outreach Center (SWROC) near Lamberton. “We know the prevention of erosion results in better utilization of nitrogen, increased organic matter in the soil and improved water quality.”
Yet there is something missing in this equation for most farmers – a harvestable crop. Traditional cover crops, such as hairy vetch for instance, do a great job at fixing large amounts of nitrogen that help meet the needs of the following crop, such as corn.
Hairy vetch will help cut down on input costs, but, by definition, a cover crop is killed off a couple of weeks before planting of a cash crop is seeded, either by machine or spraying herbicide.
“One of the objectives of my research is to determine if in the rotation of corn and soybeans, which is the most important activity that happens here in southwest Minnesota, can be improved with the addition of novel crops,” he said.
By novel crops, Garcia explains he means cover crops that could eventually become part the system as another cash crop. There are three promising candidates he’s looking at in his study: winter rye, camelina and pennycress.
“Most people look at pennycress as a weed,” Garcia said, “but there is a group of dedicated breeders in my department that are dedicated to make sure it has the economic characteristics that are needed for that specific plant to become a crop.”
The pennycress can be used as a product for the biofuel industry. According to Garcia, field pennycress can be used to create a high-quality biodiesel. In addition, both camelina and pennycress can be used as a supplement in cattle feed. However, to harvest camelina or pennycress, the time of planting and harvesting the cover crop needs to be refined from normal cover crop procedures. Garcia, in his study, is working with camelina in both a relay cropping and double cropping system.
“In double cropping, basically what you do is seed your camelina in year one in standing corn, for example,” Garcia said. “You harvest your corn and let the camelina go all the way until the following spring until it is ready to be harvested for its seed. You harvest the camelina, prepare your soil and plant your next cash crop. So you are producing two crops in one year.”
The possible difficulty with this system is that the producer may have to wait a little too long to harvest the camelina, thus shortening the growing season for the primary cash crop.
“The relay system is a little bit more complex than double cropping, but much better suited for our growing season” Garcia said. “You have your camelina from the previous year, just like you did in the double cropping system, but now, when the camelina is just beginning to flower, you come in and inter-seed your corn or soybeans.
“Let’s say you planted soybeans. They emerge and begin to grow, but grow slowly because there is shade from the camelina. “Then you come in with the combine and cut just above the soybeans and harvest the camelina. Then the soybeans keep growing.”
Garcia noted there is already research showing that double cropping is working all the way from Morris to Waseca. Now he and others in the U of M system are focusing on the relay side of the equation.
“Both systems allow you to have new crops for duel purpose,” Garcia said. “You get the benefit of the cover crop and a cash crop from the camelina, and you still get the corn and soybeans in each season, as well.”