Cover crops restore flooded fields
What’s the best approach to restoring a field that flooded during the summer? Chris Nelsen, Mission Hill, S.D., says he isn’t an expert at it, but has some experience.
On one of his fields that flooded in 2011, he started the restoration process by planting a cover crop to break up the hardpan, recycle nutrients in the soil and provide organic matter for microbial action.
“I didn’t want to do any fall tillage in that flooded field,” Nelsen says. “That would make it susceptible to wind erosion all winter. It was severely eroded that way about 15 years ago. Two years ago I removed some wind-laid dirt, grass and sod from the ditches. I re-carved the field’s drainage ways to promote in-field drainage. I needed to do something to prevent fallow syndrome.”
• Planting cover crops after flooded fields dry out is a good option.
• Cover crops will help protect the soil from wind erosion during the winter.
• South Dakota farmer uses a mix of turnip, rapeseed, sugarbeets and radishes.
Sorghum has been used in situations like Nelsen’s in the past. However, he knew that crop would hinder nitrogen uptake because of its high carbon-to-nitrogen ratio. That would hurt the following year’s corn crop. Nelsen didn’t want a tall cover crop that would leave tall, woody residue.
“I used turnip, rapeseed, sugarbeets and radishes for this mix,” Nelsen says. “My seed cost $16 per acre. I used pelletized gypsum as a carrier that cost $85 per ton and used an air-flow fertilizer spreader to distribute the seed. Overall, the cover crop cost $24.50 per acre. I added fertilizer with a spreader and used a soil finisher to work the seed in slightly. A nice rain right after I seeded resulted in a beautiful stand.”
The cover crop mix rooted down as much as 14 to 16 inches into the soil, with smaller roots measuring at least an inch in diameter. The plants stimulated microbial activity in the soil until nighttime temperatures dropped below 15 degrees F.
“Once the roots freeze, they’ll decompose. By spring there will be virtually nothing left of them,” Nelsen says. “That will leave nice voids in the soil to help absorb spring moisture.”
Cover crops beneficial
“Cover crops aren’t real common in my neighborhood,” Nelsen adds. “However, the more I learn about them and understand what they do for soil, the more I believe I’m hindering my yield potential by not using them. Soil scientists are learning more and more about the benefits of ongoing microbial action in soil. I expect to see a significant contrast in these two fields next summer.”
Nelsen, who completed his agronomy degree and minor in soil science at South Dakota State University, worked as a crop adviser a number of years before transitioning into full-time farming.
“I’m looking into other types of cover crops I could use in my fields. There’s some data on flying cover crops into standing corn. Once corn plants die back, the cover crop comes up and keeps microbial action going. That could prove to greatly facilitate my corn and bean production. I’ll experiment with some more things and see what I can achieve.”
Sorensen is from Yankton, S.D.
This article published in the June, 2012 edition of DAKOTA FARMER.