Over the past 38 years, we’ve produced a handful of No-Till Farmer articles on no-tilling corn and other crops into a living cover, such as alfalfa sod, cereal rye or wheat. But it’s a tricky maneuver and one that has not caught on among many no-tillers.
Yet with growing interest in making cover crops part of the overall no-till package and the government taking steps to protect the environment and produce cheaper fuel, it’s getting a fresh look from researchers at Iowa State University.
The scientists are testing between-row cover grasses to reduce soil runoff and keep vital nutrients in the soils. And with U.S. government targets requiring that 30% of our fuel needs be made from biomass 20 years from now, the agronomists are also looking at ways to harvest huge amounts of stover.
But as veteran no-tillers know, removing corn residue can cause more water runoff and deplete the soil of essential organic materials. So the scientists are looking at planting grasses between the corn rows that would remain on the field year-round and help keep the soil in place and replenished with organic matter.
No-Tilling Into Living Sod
“We’re trying to grow corn in a perennial sod, so that we can protect the soil and meet other environmental needs,” says Iowa State agronomist Ken Moore.
One cropping system that the team examined in 2009 increased harvest from 189 bushels of corn per acre using traditional production methods to 203 bushels with the new system. This was done while improving the soil and harvesting almost all the stover.
“It’s remarkable,” says Jeremy Singer, an agronomist at the U.S. Department of Agriculture’s National Laboratory for Agriculture and the Environment in Ames, Iowa. “Even in two bizarre years — 2008 was the year of the floods and 2009 had the coolest July on record — we harvested close to 100% of the corn stover. We’re obtaining similar yields as the no-ground-cover control, while increasing carbon additions to the soil.”
The team evaluated 36 ground covers of mostly grasses, different tillage systems such as no-till and strip-till, 50 corn hybrids and several chemical treatments.
Slow Growth Wanted
One of the keys is finding a ground cover that is less active during the spring. This allows the corn to absorb needed water and sunlight at the beginning of the growing season without competing with the grass. As the corn creates a canopy over the shorter grasses later in the spring, there is less competition for sunlight and nutrients as the corn becomes dominant.
While this research takes a fresh look at dealing with living covers, no-tillers fully understand the tremendous value of leaving crop residue in their fields. So they’re going to be skeptical of any system that results in the loss of their valuable crop residue, especially if prices paid for biomass are on the low side.