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Studying wide-row corn interseeded with cover crops

A farmer in Nebraska is trying to establish the best cover crop mixture and row spacing for grazing and grain.

Starting in 2014, Scott Heinemann of Winside, Neb., began looking at ways to lower his nitrogen inputs and herbicide expenses while building soil health and providing a grazing crop at the same time. His work led him to plant corn trials into 40-inch-wide rows and interseed cover crops into the growing corn. This practice didn’t come to Heinemann overnight.

“In 2014, I seeded sweet clover with oats,” Heinemann says. “The oats were tall and yielded great, and the sweet clover was incredible after the oats harvest. I then seeded sorghum, sudan, sunn hemp and radishes.”

The next spring, Heinemann planted shorter-season 93-day corn into that same field.

“The field yielded 193 bushels per acre, but in portions of the field where there wasn’t any sweet clover, it only yielded 168 bushels,” he says. “The sweet clover the previous year provided a 25-bushels-per-acre difference. That got me thinking about doing other things besides adding so much nitrogen.”

Heinemann started looking at soil water infiltration. “I found that even on alfalfa that had been cut, there was more runoff after a rain,” he says. “I was amazed at how the runoff into a cover crop field filtered out and went into the soil. When you start digging, you find out why.”

The biomass isn’t just above the ground, but it is also below. “For me, the one thing that amazed me was the earthworms," Heinemann says. "We always had a number of them, but I was astounded at how quickly they multiplied."

This year, Heinemann continued his study of corn in wide 40-inch rows, with the idea that interseeded cover crops would be more able to grow biomass with more sunlight penetration through the crop canopy. He tested interseeded covers in both narrow and wide rows to compare the results. He also chose cover crop species that would build nutrients in the soil and provide grazing potential in the fall.

After corn planting in May, Heinemann planted cover crops with a John Deere 7300 planter frame with 7100 row units modified to seed cover crops. “I moved the transmission of the planter to the front of the frame to accommodate 20-inch row spacing,” Heinemann says.

He used Kinze soybean meters for the large seed boxes used to plant larger-seeded cover crops. He cleaned up and reconditioned the insecticide boxes and meters to seed smaller-seeded cover crops.

“I had to ream the opening out slightly on the insecticide meters to get clover seed to feed out better,” he says. “The row units are staggered, so I can interseed one row between 20-inch corn and two rows between the wider 40-inch corn rows,” Heinemann notes. “It’s nothing fancy, but pretty inexpensive, and it does a good job.”

This season, the 40-inch corn with interseeded covers that included buckwheat yielded 148 bushels per acre. “The south half of the field had a lot of ground squirrel damage early on, and a lot of waterhemp and kochia came up in those spots,” he says. “Harvest populations in those areas were 20,000 to 25,000 plants per acre.” The north one-third of the plot yielded between 190 and 214 bushels per acre on the yield monitor, with harvest populations about 38,000.

Surprisingly, brassicas and clovers survived better in the narrow-row corn. “The buckwheat apparently liked the increased sunlight on the wide-row corn, and outcompeted the other species,” Heinemann observes. “Next year, I will cut my planting population back to 30,000 seeds per acre and decrease the amount of buckwheat in my cover crop mix, or perhaps eliminate it altogether in some portions of the field.”

Heinemann admits that he needs a ground squirrel management plan to eliminate that problem. “There would be a lot of grazing potential if I can get this system figured out,” he adds. “There is no such thing as failure if we learn from our mistakes.”

TAGS: Cover Crops
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