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Palmer Amaranth Opened the Door to Cover Crops and No-Till on Arkansas Farm
Five years ago, brothers Adam and Seth Chappell were on a treadmill that offered little hope of escape. Farming 8,000 acres near Cotton Plant, Arkansas, the Chappells struggled with an invasion of the herbicide-resistant weed Palmer amaranth.
“It was a killer,” says Adam. “We were spending $100 an acre on herbicides just to attack a weed. The way we were going, I was expecting us to have to get out of farming. There was no way for us to be profitable.”
The brothers made changes that branded them as “nuts” in their community. Today, they grow a diverse rotation of non-GMO corn, cotton, soybeans, and rice. Breaking from a tradition of tillage, they now no-till their fields and plant every acre to a cover crop.
“Palmer amaranth is still a problem, but it’s not a devastating problem,” says Adam.
Cover crops and a transition to no-till have subdued the weed on their farm. The steps they took to adopting these practices began when Adam got the idea to find out how organic growers fought weeds.
“Online I found a video of an organic producer in Pennsylvania, and that guy’s fields were clean,” says Adam. “He was controlling weeds with residue from a cereal rye cover crop. He crimped the rye to terminate it.”
Cereal Rye Snuffs Palmer Amaranth
Hoping for similar results, the Chappells no-tilled cereal rye one October into 300 acres of cotton and soybean stubble.
“The rye did really well the following spring,” says Adam. “The shade from the rye kept the Palmer amaranth from emerging. We terminated the rye two weeks before planting the next crop. Throughout the growing season we were able to control the Palmer and other weeds by using a lot less herbicide than we had been using.”
So encouraged were the Chappells that they increased their planting of a cereal rye cover crop to 2,500 acres.
Today, the cover crops growing across their entire acreage are more diverse. Their fall-seeded cover crop blends typically include cereal rye, black oats, triticale, hairy vetch, daikon radish, Austrian winter peas, and crimson clover.
Summer cover crop blends may include Sudan grass, sunn hemp, and sunflower.
“The species we plant depends on when we get the cover crop planted,” says Adam. “We try to plant cover crops in late August or early September.”
They adjust the species in the blend to fit the subsequent crop. A cover crop being seeded into corn stubble, for instance, will include radish to scavenge and store residual nutrients for the next crop. A cover crop going into cotton stubble will have hairy vetch in the blend.
“We plant cereal rye and black oats at a rate of 30 pounds per acre each,” says Adam. “When we include radish, we seed it at a rate of 2 to 3 pounds per acre. We want our cover crops to grow a lot of above-ground biomass that leaves a thick layer of residue on the surface after the cover crop is terminated.”
The combination of growing cover crops and eliminating tillage (see sidebar story) has reduced the Chappells’ costs for inputs. “We were spending more than $100 an acre for herbicide, and now that’s down to $20 to $30 an acre,” says Adam.
“We’ve also been able to reduce our fertilizer cost by 20% without reducing yield, but we’re several years away from being able to make major reductions in nitrogen applications,” he says. “We’re approaching that cautiously. We’ve got strip trials on our farm, where we’re evaluating how crops do with varying rates of N.”
The Chappells’ yields have held even, with areas in fields that were previously unproductive, now beginning to produce. “There are places in dryland fields that are doing better probably because of increased residue on the soil surface,” says Adam.
Yet perhaps of greatest significance as a result of their changes in farming practices is that soil has improved and soil erosion is diminished or eliminated.
“Our only goal initially was to control one weed,” he says. “But other problems like soil erosion and soil quality also got addressed through the changes. The organic matter in our sandy loam soil has gone up a full percentage point, and the infiltration rate of the soil has gone up exponentially. Because of the improved water-holding capacity of the soil, we don’t have to furrow-irrigate as often as we did before.
“Soil erosion is gone,” he says. “Our fields don’t have gullies, and in the spring when the wind is blowing, there are no sand clouds over our farm. Any water that comes off the fields is clean.” All told, the changes the Chappells have made point them toward a hopeful future.
“I feel better about our opportunities than I did before,” says Adam. “No-till and cover crops have put us on a path to surviving and even being profitable, which wasn’t possible five years ago. We have the potential to be profitable now because we’re not spending as much money on inputs.”
Changes Stop Erosion
As fourth-generation cotton farmers from Cotton Plant, Arkansas, Adam and Seth Chappell grew up with the traditional practice of using “lots of tillage” in order to prepare ridged seedbeds for row crops.
Because of the flat topography of their farm, water from furrow irrigation and rainfall tended to stand in the fields. Planting the row crops in the ridges helped the crops “keep their feet dry,” says Adam.
The heavy tillage led to wind and surface erosion of soil, though. “We’d have big gullies in fields,” he says.
The erosion was troublesome to the Chappells, and even before the retirement of their father, Dewayne, the family began a gradual transition to more conserving practices. The first step was to plant a subsequent row crop in the previous crop’s ridges, a practice made possible by precision technology. Thus, the tillage needed to create a new seedbed was eliminated.
With the Chappells’ use of no-till and the planting of cover crops, the resultant improvements in water infiltration into the soil profile have removed the need for ridged seedbeds.
“We’re able to plant on a flat surface because we no longer have water standing in the fields,” says Adam.