Freshly prepared and planted farm fields are a sign of spring in Minnesota. We first begin to see corn and then soybeans poking out of the ground. When spring rain storms come, the crops are small and unable to shield the soil from the pounding rain. With the rain storms Scott County experienced in mid-May, rain water was rushing across the landscape. Much of this water ran across farm fields, picking up loose soil and carrying it into our lakes and streams. This causes farmers to loose valuable topsoil, and waterbodies fill with sediment and excess nutrients which can damage habitat. But what can be done? Farmers need to get their crops in the ground, and it rains in the spring. One promising solution is cover crops.
More and more farmers are turning to cover crops as a way to preserve their investment and to maintain and build their soil health rather than losing topsoil to lakes and rivers. One of those farmers is Jim Schwinger, who farms near Jordan.
Jim inter-seeded a cover crop of annual rye and canola into standing corn last June. The rye and canola germinated and went into a state of dormancy while the corn was growing. Once the corn was harvested, the cover crop responded quickly to increased sunlight and grew tall. This protected the soil in the field throughout the fall, winter, and spring from wind and water erosion. The cover crop was terminated with herbicide in early May to prepare the field for seeding soybeans. Even after it was terminated, residue from the cover crop continued to provide protection from erosion. When heavy rains hit in mid-May the field experienced little to no erosion loss. The cover crops roots had created channels in the soil, so more water soaked into the ground instead of washing over the field. The water that did not immediately soak in was slowed down by plant residue, so it had less power to pick up soil particles and create gullies.
The photo on the left is a field without cover crops showing washing after heavy rains.
The photo on the right shows Jim's field with cover crops without signs of erosion after heavy rains.
After the field was dry enough, Jim used a no-till planter to seed soybeans. Some farmers who are considering cover crops worry that with the rains like Scott County experienced in May, having a cover crop on the field would cause the soil to dry out more slowly, delaying planting. Jim is on his third year of cover crops and has not found this to be the case. The cover crop actually pulls water out of the soil for the plants to use,