Tips for Managing Cover Crops
April 12, 2016
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 today shared a number of spring management tips for farmers new to growing cover crops.
“We continue to see significant growth in the number of farmers using cover crops on their farm and also the total acreage of cover crops in the state. As a result, farmers are seeing the benefits firsthand around reduced erosion, improved water quality and soil health benefits,” Northey said. “With good soil moisture and warm spring weather we are seeing very good cover crop growth. This makes good management this spring even more important.”
It’s important to allow the cover crop to grow as long as possible to maximize the benefits of reducing erosion and improving soil health. This is typically easier for soybeans after cover crops because of the later planting date and less potential impact on soybeans following a winter cereal grain. For corn, it’s important to terminate cover crops 10-14 days ahead of planting. More experienced users may be more comfortable with closer termination windows.
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 your farming operation can be found atwww.cleanwateriowa.org/farm-practices.aspx or at www.extension.iastate.edu/ilf/content/cover-crop-resources
1) Evaluate for winter kill – The mild and wet winter, coupled with an early spring has provided near optimal conditions for cover crop growth. Cover crop species that may normally winter-kill may have over wintered. It’s important to assess cover crop fields survived the winter to inform management decisions. If the above ground cover crop is brown and near the soil surface no green plant material is present then your 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.
2) 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:
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.
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.
3) 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 it is most needed. 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 lbs of nitrogen at or near corn planting. This is not additional nitrogen, but within the farmer’s total fertilizer program.
4) 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 2/3rds of Iowa) must be terminated within 5 days of cash crop planting. If using no-till add 7 days to either scenario. More information about insurance requirements can be found at www.rma.usda.gov/help/faq/covercrops2016.html.
5) 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 at www.weeds.iastate.edu/mgmt/2015/CCherbicides.pdf
6) Consider participating in the Conservation Technology Information Center’s annual cover crop survey – The Conservation Technology Information Center (CTIC) conducts an annual cover crop survey of all farmers, whether they plant cover crops or not. Farmers can take the 10-15 minute survey completely anonymously and it helps guide policy, research and education on cover crops nationwide. The survey is available at www.conservationinformation.org/Cover%20Crops.
“Hopefully these tips and the resources that are available statewide will help farmers have success as they manage their cover crops this spring. We want farmers to have a successful experience and be encouraged to try cover crops again in the future,” Northey said.
Background on Iowa Water Quality Initiative
The Iowa Water Quality Initiative was established in 2013 to help implement the Nutrient Reduction Strategy, which is a science and technology based approach to achieving a 45 percent reduction in nitrogen and phosphorus losses to our waters. The strategy brings together both point sources, such as municipal wastewater treatment plants and industrial facilities, and nonpoint sources, including farm fields and urban stormwater runoff, to address these issues.
The initiative seeks to harness the collective ability of both private and public resources and organizations to deliver a clear and consistent message to stakeholders to reduce nutrient loss and improve water quality.
As part of the initiative, last fall 1,800 farmers committed $3.5 million in cost share funds to install nutrient reduction practices in each of Iowa’s 99 counties. The practices that were eligible for this funding are cover crops, no-till or strip till, or using a nitrification inhibitor when applying fall fertilizer. Participants include 980 farmers using a practice for the first time and more than 830 past users that are trying cover crops again and are receiving a reduced-rate of cost share. Farmers using cost share funding contribute 50% or more to the total cost of the practice.
There are also currently 45 existing demonstration projects located across the state to help implement and demonstrate water quality practices through the initiative. This includes 16 targeted watershed projects, 7 projects focused on expanding the use and innovative delivery of water quality practices and 22 urban water quality demonstration projects. More than 100 organizations are participating in these projects. These partners will provide $19.31 million dollars to go with over $12 million in state funding going to these projects.
More than $325 million in state and federal funds have been directed to programs with water quality benefits in Iowa last year. This total does not include the cost share amount that farmers pay to match state and federal programs and funds spent to build practices built without government assistance.