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Cover crops can help prevent black snow banks

Producers use cover crops for a variety of reasons: to increase carbon in the soil, control weed pressure, and reduce soil erosion and nutrient loss, to name a few. Much of our agricultural soil in Minnesota could benefit from reduced erosion and nutrient runoff. The high intensity corn-soybean agricultural systems of Minnesota typically consist of a fallow, or bare, period from harvest until the next season’s planting.  In other words, most of our soils are bare during the winter months.

Soil and nutrients are most commonly lost through leaching, tile drain discharge, surface runoff, and wind erosion. Approximately 80% of the world’s agricultural land experiences moderate to severe erosion. United States agriculture hosts some of the lowest average erosion rates globally, but these erosion rates still exceed the rate of soil formation; cropland loses soil faster than the soil formation process can replace it. Erosion is caused, in part, by soil being left bare and exposed to water movement and wind erosion, which is why we sometimes see black snow banks. That’s right – we lose our valuable, fertile topsoil to the piles of snow in the ditches. Many producers who use cover crops are attempting to retain soil and nutrients in their fields.

Many Minnesota crop producers acknowledge that cover crops are a useful tool for combatting erosion, but face challenges in utilizing cover crops. The biggest challenge of successful cover cropping in Minnesota is the short growing season. Several studies at the University of Minnesota aim to identify and improve options for interseeding cover crops into standing corn to allow cover crops enough time to grow before winter hits and establish roots that can hold soil over winter.

Researchers are trying to determine the best time and method to plant cover into row crops. Most literature and producer experience suggest that cover crop planting dates which align with the V5 to V7 corn leaf stage don’t impact corn yield because planting takes place near the end of the critical weed-free period in corn. This timing also usually allows the cover crops to establish before winter.

Additionally, because planting cover crops involves additional field operations, it makes economic sense to combine cover crop interseeding with scheduled cash crop tasks, like planting cover crops while side dressing fertilizer, which can be timed to happen within the time period in which corn is at the V5 to V7 stage. Several crop producers in Rice and Steele Counties have been implementing cover crops by aerially seeding with a plane, usually in collaboration with other farmers, or by drilling cover crop seed between the rows while side dressing fertilizer.

There is plenty of evidence that cover crops can benefit soil health for a variety of reasons, and current work is aiming to determine optimal cover crop mixes, planting methods, and planting dates. The fact that research is in the works does not discourage crop producers from trying different things and discovering what works to keep their soil on their own farms during winter.