By Drake Larsen, Practical Farmers of Iowa
Diversity is the foundation of any sustainable agriculture system, and cover crops are a great management tool for bringing diversity to the farm. The addition of cover crops increases plant diversity and helps to support biodiversity in soil microbes and beneficial wildlife. Cover crops also help protect biodiversity off the farm by holding nutrients such as nitrogen and phosphorus in the fields, which protects water and other downstream ecosystems. Crucial for building soil and preventing erosion, cover crops also are important for increasing fertility and water-holding capacity, and controlling weeds, disease, and insect pests of organic crops.
Diversity can come to the farm in many ways. There is diversity in space—having multiple plant and animal species occupy the same plot of land at the same time. There is diversity across scales—having multiple land covers and animals occurring on different parts of the farm. There is also diversity across time—having different plants or animals in a certain plot of land at different times of the year. Cover crops can be used to bring greater diversity to your farm in each of these ways.
Added diversity also helps the farm’s bottom line. While cover crops are often cast as being a non-income-producing crop—contributing to long-term sustainability but adding a short-term cost—when used in a whole farm system, their value can be immediate. Beyond biodiversity, harvested cover crops can contribute to income diversity, an important part of making a farm more resilient to financial shocks such as market volatility, increased input costs, or unfavorable weather.
A Penny Saved is a Penny Earned
Soil health was on his mind when North-Central Illinois organic farmer, Tom Yucus, first started thinking about cover crops. An Organic University course at a MOSES Organic Farming Conference some 15 years ago really ignited his thinking on the matter. At the time he was farming conventionally. No-till was the first step in his journey to organic. The organic price premiums solidified the decision to transition his farm to organic 9 years ago.
“Always have something green out there,” Tom says. Good cover protects the soil between crops and builds soil fertility when incorporated in the soil as a green manure. His first cover crop attempt, planting spring oats, unfortunately wasn’t a great experience for Tom. The cover crop went to seed and the volunteer oats became a weed themselves. But Tom stuck with it, and over time learned to manage cover crops more effectively. For instance, he is now using a heavier disk, which is less likely to skip on the surface when he is shallow disking at two to four inches to terminate the cover.
As Tom has experimented with other cover crops and mixes of multiple species, other benefits have become apparent. When farming conventionally, Tom was often concerned about his own health. He got sick every spring, and his instincts told him it had something to do with the insecticides in the planter boxes. He was concerned also about using anhydrous ammonia, another hazardous substance that was standard practice in the conventional system. Now, “I’m growing my own nitrogen,” Tom says, “and saving money using cover crops to suppress pests.”
While pulling steel will always be an important part of weed management on the organic farm, cover crops also help to smoother weeds. With careful timing of cover crop termination, flushes of weeds can be targeted and eliminated more effectively with one pass.
Do More with What you Have
The quest to increase farm income often leads farmers to expand their land base. David Bishop, an organic farmer from central Illinois, suggests that “doing more with what you have is better than just getting more land.”
Cover crops help Dave achieve an important rule-of-thumb on his farm, “I want to get three incomes from the same field every year,” he says. Considering that his main cash grain crops are annual plants grown in monocultures, cover crops are integral to achieving this goal.
For example: when wheat is the main cash grain crop, red clover will be frost-seeded in the spring. The clover germinates and is ready to grow as soon as the wheat is harvested. Wheat is the first income harvested from the field. In the fall, beef cattle are turned into the field and allowed to graze the clover; meat becomes the second income from the field. As the leguminous clover is grazed, the roots slough off into the soil while at the same time beef are spreading manure across the field. Between the clover and the cattle manure, 160 units of nitrogen becomes the third “income stream” or benefit gained for the field that year. While the wheat crop may bring in $360/acre, the benefits of grazing and nitrogen fixation for future crop success easily double the net income.
Using cover crops to improve soil health makes each acre of Dave’s land more productive over time, too. But it didn’t happen right away. The Bishop Farm is on sandier soils than the rich, deep soils that surround him. At first his organic corn fields didn’t yield quite as well as surrounding farms. Over time, though, with the use of cover crops and other organic techniques, his soil has improved dramatically. When Dave transitioned his land to organic in 2004, the soil organic matter was 1.7%. Today, the soil organic matter is 3.5% and Dave’s corn yields match or beat conventional averages for the area.
Advice for Getting Started with Cover Crops
Cover crops are gaining popularity in both organic and conventional farming systems across the Midwest. This is an important step in agricultural sustainability, but it doesn’t come without added management challenges. While there is great potential for both short-term and long-term gains, there’s potential for headaches, too. Here is some advice from Tom and Dave on bringing cover crops into your farming system:
• Decide on your purpose for using cover crops in a given field or part of a field. There are many benefits to cover cropping, we’ve touched on just a few of them here. You will be well served to decide explicitly which benefits you hope to gain. Erosion control, growing nitrogen, providing forage–all can be part of the plan, but you must decide what is most important in each field.
• Find a good cover crop decision tool for your area. Cover crops behave differently in different places,especially considering the rainfall gradient from east to west in the Corn Belt, and difference in growing calendar from south to north. While some general information is useful, it is important to seek out local-specific information as you make cover crop decisions. The Midwest Cover Crops Council has developed a Cover Crop Decision Tool that posts regular data updates useful for 8 Midwest states and Ontario, Canada crops and conditions. www.mccc.msu.edu/selectorINTRO.html
• Start small. There is a learning curve to cover crop management, and it’s best to learn on small acreage rather than have a big mess on your hands. If you are hoping to get forage value out of your cover crops, perhaps the crop field next to the pasture is a good place to start. If you are looking for erosion control, hill slopes and areas prone to concentrated flow might be best for experimentation.
• Start simple. While many experienced cover crop users eventually turn to planting diverse mixes, keep it simple at first. Many suggest a cover that is prone to winter-kill for starters, oats for instance, to eliminate the extra management needed for spring termination.
• Don’t give up. Cover crops might not germinate fully and fail in drought years. Or in a mild winter, the spring termination might be more of a hassle.
• Learn from other farmers through workshops, field days and on-farm demonstration. As you gain experience with cover crops, open your farm so that others can learn from you. There will be workshops on cover crop management at the 2014 MOSES Organic Farming Conference, watch for the Conference Registration Guide in your mailbox soon, or visit www.mosesorganic.org. MOSES also will be planning at least one cover crop field day in 2014.
• Support on-farm research. We are all still learning about cover crops. Universities and farmer groups, such as Practical Farmers of Iowa, are helping to minimize the learning curve. There is nothing more valuable than on-farm research to increase farmer knowledge on proper management of cover crops.
Drake Larsen is Communications and Policy Associate of Practical Farmers of Iowa.