Northey shares tips for managing cover crops

As the number of Iowa farmers using cover crops continues to grow, it’s important to help make sure these farmers have a successful experience. Iowa Secretary of Agriculture Bill Northey recently shared a number of spring management tips for farmers new to growing cover crops.
“We have seen tremendous growth in the number of farmers using cover crops on their farm as they seek to reduce erosion, protect water quality and improve soil health. As with any new practice there can be a significant learning curve. These tips can hopefully help farmers have a successful experience which encourages them to grow cover crops again in the future,” Northey said.
This information was put together with the help of the Iowa cover crop working group, which includes representatives from the Iowa Department of Agriculture and Land Stewardship, Practical Farmers of Iowa, Iowa State University, Iowa Learning Farms, and USDA Agriculture Research Service. More information about incorporating cover crops into a farming operation can be found at  or at
• Evaluate for winter kill. If the above ground cover crop is brown and near the soil surface no green plant material is present then the cover crop winter-killed. Cover crops such as tillage radishes and oats typically winter kill and then no additional spring management is needed. Other cover crops, such as winter or cereal rye, winter wheat, triticale, and barley, consistently over-winters in Iowa. In late March, double check plant stems near soil surface to see if the plant has survived.
• Termination options. Herbicides, tillage or a combination of the two can be used to effectively manage cover crops in the spring.  Keep in mind any tillage will reduce the effectiveness of the cover crop residue to protect against erosion and suppress weeds. Some additional considerations for both methods of termination follow:
Herbicide - For successful herbicide termination, make sure the plant has “greened-up” and has enough living surface area for the herbicide to work. Experienced farmers suggest spraying during the middle of the day and, if possible, spray when air temperature is at least 45 or 50F. Unless you have experience, separate nitrogen application from a “burndown” herbicide application.
Tillage - Terminating cover crops with tillage can be effective, but may take more than one tillage pass. Wet periods can delay tillage to terminate cover crops and wet conditions following tillage can allow cover crop plants to survive tillage operations. Also, tilling a cover crop to terminate eliminates the erosion prevention benefit that the cover crop would usually provide in the early part of the growing season.
• Consider nitrogen needs. Cover crops effectively sequester nitrogen and as the plant residue breaks down it will release its nutrients, making them available for the crop later in the season when they need them the most. However, there is the potential for lower available nitrogen early in the growing season, especially following an overwintering grass cover crop like cereal rye. To protect yield, farmers growing corn after a cereal rye cover crop may want to apply 30-50 pounds of nitrogen at or near corn planting. This is not additional nitrogen, but within the farmer’s total fertilizer program.
• Know crop insurance requirements. Crop insurance rules state that a cover crop in Zone 3 (western third of Iowa) must be terminated by the day of cash crop planting. A cover crop in Zone 4 (eastern 2/3 of Iowa) must be terminated within five days of cash crop planting. If using no-till, add seven days to either scenario. More information about insurance requirements can be found at
• Start planning now for cover crop needs this fall. Determine what cover crop(s) work with your current or planned crop protection program. Some residual herbicides have carryover restrictions for certain species of cover crops. Consult with your agronomist and/or cover crop seed representative to look at your specific management system with the integration of cover crops. Additional information can be found

More than 1,600 farmers have volunteered to invest $4.2 million to try a new practice on their farm to better protect water quality over the past two years through the Iowa Water Quality Initiative. Thousands of other Iowa farmers are using cost share through other state and federal programs or growing cover crops on their own with no assistance.
Iowa also currently has 16 Water Quality Initiative demonstration projects in targeted watersheds that are focused on helping farmers implement and demonstrate water quality practices. The state has provided $7.4 million in funding to support these projects and has leveraged an additional $11.7 million in additional funding from partners and landowners. More than 95 organizations are participating in these projects.
Visit to learn more about voluntary, science-based practices that can be implemented on  farms and in cities to improve water quality. Iowans can also follow @CleanWaterIowa on twitter or “like” the page on Facebook to receive updates and other information about the ongoing Iowa water quality initiative.