STRETCH ROWS ACCOMMODATE CORN AND COVER CROPS
Okay, after years of witnessing increasingly dense plantings, this is just weird. But...
Although data are still being compiled on a statistically significant basis, corn in 60- and 90-inch rows has roughly yielded 15% to 20% less than corn growing in 30-inch rows in 2019-2020 CRWP trials, says Kraus.
Lower yields don’t always occur, though. In 2020, Purfeerst’s corn planted in 60-inch rows with cover crops yielded 224 bushels per acre. This eclipsed the 209.4- and 217.7-bushel-per-acre yields for corn planted in 30-inch rows with no cover crops and cover crops, respectively.
An even bigger key from these row systems is biomass production.
“We can grow more biomass in 60- and 90-inch-wide rows than in 30-inch rows,” says Purfeerst.
Cover crops grown in wide rows in CRWP trials have generated from 1,000 to 1,600 pounds of dry matter forage per acre, adds Kraus. That contrasts with just around 100-pounds-per-acre levels in 30-inch rows interseeded with cover crops, he says.
“It is also high quality,” he says, ranking 190 in relative feed value, a high value within a ranking system to assess livestock feed quality.
Bill Lazarus, a U of M Extension economist, performed a preliminary analysis that determined that 1,000 pounds per acre of high-quality dry matter forage could make up for a 15% corn yield hit incurred by widening corn rows beyond 30 inches. (This analysis does not include corn stover value when compared with the 30-inch row control with no cover crop.)
Grazing cover crops following corn harvest also enhances soil fertility via the passage of manure, Purfeerst adds.
Extra costs exist, though. Cover crop seed cost Purfeerst $16.52 per acre, while interseeding the cover crop in corn at the V4 stage cost $12 per acre.
Still, the CRWP’s findings on the biomass boost can translate into cover crop grazing benefits. A Practical Farmers of Iowa study funded by the Iowa Department of Agriculture and Land Stewardship Water Quality Initiative showed cover crop grazing profits averaged $76.48 per acre among six farmer-cooperators who grazed cover crop systems from 2018 to 2019. Profits varied from $34.01 to $119.38 per acre, depending on cover crop seeding rate and date, individual farm costs, grazing periods, and number of cattle.
