Nearly 20 years ago, corn and soybean grower Rick Clark, of Williamsport, Indiana, got fed up with soil blowing and washing off his farm due to tillage. “I decided it was time to try something different,” he says.
First, he stopped tilling. Then, he started growing cover crops, and he also began imagining ways he could eliminate the fertilizers and herbicides he’d thought he needed. His imagination led him to create a whole-farm system he calls “organic regenerative stewardship.”
Now, as a no-till, certified organic producer, Clark grows corn, soybeans, winter wheat, alfalfa, buckwheat, and peas on 7,000 acres. Every acre grows cover crops.
While cover crops may be the critical components in the building of his organic no-till system, it’s Clark’s strategic selection of cover crop species and attention to cover crop growth stages that shape the effectiveness of his system.
He measures his progress not in crop yields, which have declined compared with his earlier yields grown under conventional practices, but on increases in soil health and a higher return on investment (ROI). The higher ROI results from savings in purchased inputs.
“Besides eliminating tillage, I’ve also eliminated most purchased inputs, and that saves me about $2 million a year,” he says.
Soil health has also improved. “Soil organic matter has increased by 1.5% in the last 10 years, and water infiltration is about 20 inches per hour,” Clark says.
Cover crop selection
Clark’s system centers on choosing cover crop species that best fit the subsequent cash crop. He then manages those cover crops for maximum performance. For instance, his cover crop strategy before planting corn focuses on fixing nitrogen. He plants corn in fields that have grown a cereal grain such as winter wheat, barley, or cereal rye.
“I harvest the wheat in mid-July and then plant a cocktail cover crop, with legumes included that will provide nitrogen for corn the following spring,” he says. The mix includes legumes such as balansa clover and WinterKing hairy vetch, two species that can overwinter in his environment.
The following spring, he delays planting corn until after Mother’s Day. At that time the legumes are tall, mature, and blooming. “I want to give the cover crop plenty of time to do what it was intended to do, which is fix nitrogen,” he says. “At that point the cover crops are about done growing; they’ve reached the end of their life cycle.”
At that stage of maturity, the plants in the cover crop mix that have overwintered are more readily terminated mechanically, with a roller crimper or a flail chopper. “Depending upon the growth stage of the legumes, it may take more than one pass to terminate the cover crop,” Clark says.
Tracks and tires: Father & son restore Caterpillar crawlers
The cover crop sometimes produces as much as 12,000 pounds of biomass per acre; typically, Clark has planted the corn into this cover crop while it’s standing. “But recently I’ve been leaning more toward planting the corn after terminating the cover crop,” he says. “This gives corn a little more time to come out of the ground. Corn doesn’t like competition.”
Rick Clark uses a whole-farm system he calls âorganic regenerative stewardship.â.
Courtesy of Rick Clark
Weed suppression
To prevent weeds from taking hold and outcompeting corn, Clark depends primarily on the thick mat of cover crop residue, sheltering the soil and inhibiting weed-seed germination. “The mat is suppressing weeds, but it has to be consumed by soil microbes in order to convert nitrogen into forms available to the plants,” he says. “That means the corn has to canopy before all the mulch is consumed by the microbes.”
The developing corn canopy further suppresses weeds; to encourage early canopy formation, Clark plants corn in 20-inch rows.
“I have a 70-30 rule,” he says. “Seventy percent of the weed suppression needs to come from the cover crop residue, and 30% needs to come from the plant canopy. I want corn to canopy by growth stage V6.”
Clark says a cold-tolerant pea is a cover crop alternative that works well before corn or soybeans. “We harvest beans later in the fall, and planting cold-tolerant peas opens up the window of opportunity for planting a cover crop by about 45 days,” he says. “We can plant peas all the way up until the ground freezes, which is usually in December here. The peas survive the winter, and grow well in spring to fix nitrogen in the soil.”
After Mother’s Day, he plants corn or milo into the peas. He terminates the peas with a roller crimper or flail chopper.
The cover crop Clark plants most frequently after harvesting corn in mid-October is maslin, an age-old mix of cereal grains. Clark’s maslin is a blend of cereal rye, winter wheat, and barley. “The maslin grows in the fall and again in the spring after coming out of dormancy,” he says.
In spring, he no-tills soybeans into the maslin and lets both crops grow together. He harvests beans and maslin together in late September or early October and separates the grain from the beans after harvest. While the maslin matures more rapidly than the soybeans, Clark sees little loss in the maslin’s grain quality despite its relatively late harvest date.
“I sell the maslin grain to an organic dairy, and the soybeans to a food processor,” he says.
After harvesting the maslin-soybean mix, Clark replants maslin, harvesting the crop in July for grain. After the maslin harvest, he plants alfalfa (see “Terminating alfalfa with corn” below) or buckwheat. The buckwheat canopy effectively terminates small, late weeds, he says.
If a buckwheat field is slated for corn the following spring, after harvesting the buckwheat, Clark plants a cover crop mix of cereal rye and cold-tolerant peas. “The cover crop provides fuel for the corn the next spring,” he says.
While the whole-farm system Clark has developed takes careful planning and strategic management, he has found its benefits to be worth the extra effort. “My version of success is not based on crop yield,” he says. “Rather, it’s based on building soil health and maximizing return on investment.”
Agriculture.com