Cover Crops: Seeing Green in Post-Harvest Fields
In the heartland, fall is no longer just harvest season. For many, planting cover crops will be an integral part of the overall #Harvest16 game plan.
Despite falling commodity prices and challenges surrounding farm profitability, the growing use of cover crops is maintaining, if not gaining, momentum in Missouri. Cover crops are no longer just a conservation practice, but an integral part of the crop management system, specifically targeting the soil health management element. This continued momentum also fuels considerable discussion: Why are farmers investing in cover crops? Do the benefits outweigh the costs? What are the main benefits farmers seek from those plantings?
Straight From the Farmer’s Mouth
Johnny Hunter, a Stoddard County farmer and Missouri Soybean Association district seven director, says he has observed five reasons more farmers should consider adding cover crops to their farming operation. Those five include:
1. Improved Profitability
“The fields we’ve cover cropped have healthier soil profiles and more consistent yield,” Hunter says. “They’re less volatile and we don’t see wild fluctuations in production. That consistency results in better yields and higher profits.”
2. Reduced Inputs
“We lean on our cover crops to scavenge nutrients and fix nitrogen for our cash crops. Last year, our cover created 74 pounds of nitrogen per acre, or the equivalent of $28 per acre according to our soil nitrate testing. The more nitrogen we can produce through cover cropping, the less we have to purchase.”
3. Savings on Herbicides
Cover crops provide natural weed suppression that allows Hunter to forgo some of the herbicide applications he has to make in his non-cover-cropped fields.
“I see the cover crops almost like a residual herbicide,” Hunter says. “I let my cover grow big and tall so that it forms a blanket of biomass that keeps weeds from emerging. We also plant cereal rye that has allelopathic properties that reduces pigweed populations. The cereal rye has helped us dramatically reduce pigweed in our fields.”
4. Enhanced Water Infiltration
Hunter uses moisture monitors buried 4 inches, 8 inches and 12 inches deep in his fields to help determine when his crops need irrigation. He’s found his cover-cropped fields do a much better job of absorbing rainfall than his fields without cover.
“A half-inch rain usually only shows activity at the 4-inch level in our fields where we haven’t planted cover crops. Whereas we’ll see water reaching all the way down to our deepest sensors in our fields with cover. The tiny fibrous roots of the cover crops really help water find its way deeper into the soil and greatly increases the soil’s water-holding capacity.”
The enhanced moisture retention of the soils in his fields with cover allows Hunter to reduce his irrigation costs.
5. Erosion Control and Runoff Prevention
“Cover crops protect our soils from blowing and washing away with their living roots that help to hold the soil in place. The cover also shields the dirt from direct contact with rain droplets, preventing soil particles from detaching from the soil, where they are more susceptible to erosion.”
Think Outside the Box, But Do Your Homework First
Incorporating cover crops into a farm’s overall crop management strategy will provide a multitude of benefits, but it’s not a one and done or a plant and walk away type of practice. For a successful cover crop experience, some up front planning and goal setting should be part of the overall strategy to help ensure you meet your priority objectives. Cover crops require a generous investment of time and money as well as management effort, all of which coincides with the hectic harvest and planting season. It can all become a bit overwhelming. Therefore, it’s important to think strategically about cover crops and how they best fit into a given farming operation to ensure that the benefits received justify the time and investment.
One thing heard repeatedly from farmers is that the successful transition to using cover crops involves a learning curve and thinking outside the box. Every farm operation is different, and first-time cover-croppers should start small and learn first-hand what works (and perhaps more importantly what doesn’t work) on one’s own farm. Priority number one should always be getting the cash crop successfully planted. Starting small will minimize planting risks and maximize successful long-term implementation.
Determine up front your key objectives for using cover crops. This is important not only to help you measure results afterwards, but also will guide certain decisions you will need to make on the front end. Certain objectives will influence your decisions. For example, selecting the right cover crop species (or mix of species), the right seeding rate, planting method and timing as well as termination method and timing, all play a significant role in meeting different objectives.
One might think that cover crop stands should always look thick and lush, however researchers have found the best cover crop for your fields may not be as pretty as a picture. “The photos you often see are of the best stands, which has contributed to the impression that cover crop stands should be thick,” says Joel Gruver, Western Illinois University soil science associate professor. “A thick stand increases cost, increases risk of interference with the subsequent crop and is not necessary to achieve significant conservation benefits.”
The optimum stand depends on what you want to accomplish. Lyons explains that cereal rye for weed control may require a bushel or more per acre, but simply working to improve soil health may require one-half to two-thirds of that. And if cover crop forage will be grazed or is in an erosion-prone area, consider planting a higher rate than in a less-intensive management situation.
New Farmer Survey Data Tells an Encouraging Story
Despite the sagging farm economy and the added investment of cover crops, on-farm data shows continued growth of acres being devoted to cover crops. Clearly farmers are seeing this investment as a worthwhile effort. But why?
Understanding the perceived benefits of cover crops has been a major focus of the Conservation Technology Information Center’s (CTIC) Cover Crop Survey project since its inception. The fourth annual 2016 CTIC Cover Crop Survey collected data from 2,020 farmers from across the US. These surveys have charted a steady rise in cover crop acres and use since 2010, and projected plantings in the summer/fall of 2016 were expected to continue the trend, despite a bearish agricultural economy.
The survey also showed that of all the possible benefits gained from cover crops, the top three by far according to farmers were, in order of score, “Increases overall soil health” (1,219 positive answers; 86%); “Reduces soil erosion” (1,174; 83%); and “Increases soil organic matter” (1,163; 82%).
Farmers also reported modest yield gains in both corn (1.9%) and soybeans (2.8%) following the use of cover crops, and while a majority saw no loss in profit or lacked the data to tell, about one-third found profit increase from cover crops, while only 5.7 percent had a reduction in profit.
Cereal rye was reported to boost soybean yields on a majority of farms, and 82 percent indicated that cereal rye as a cover helped reduce weed problems. Notably, 26 percent specifically indicated cereal rye improved control of troublesome herbicide-resistant weeds.
Asked whether cover crops reduced yield variability during extreme weather events, two-thirds of the respondents agreed to seeing that benefit. Cereal rye was the most popular single species of cover crop, but mixes of two or more species were also popular and growing.
Cover crops are a priority area for the Missouri Soybean Association and Missouri Soybean Merchandising Council. In addition to implementing cover crops on the Association’s Bay Farm Research Facility in Boone County, the Merchandising Council is working with growers statewide on a strip trial program and other efforts to increase the understanding of both the challenges and benefits brought by implementing cover crops. Learn more online at mosoy.org.