Ben and Andy Johnson are accustomed to bucking the conventional thinking that their Floyd County farm is too far north and soils are too heavy for cover crops and reduced tillage. The brothers have tapped into a network of family and friends to figure out ways to make the conservation practices work effectively.
“We’re not pioneers by any means. It’s basically by asking different farmers what they’re doing; not being afraid to ask questions and not being afraid to try different things,” Ben says.
Some neighbors expressed doubt at their initial efforts to strip-till corn and no-till soybeans, telling the brothers they’d regret not turning the soil black, Ben remembers. They did it anyway, and haven’t regretted their decision. Yields are at least comparable to conventional tillage, soil health has improved and the labor and time savings are a bonus.
“Labor is the biggest reason that we do strip-till and no-till,” Ben says. “We don’t have enough time in the spring. That allows us to plant corn or beans instead of doing tillage. Our opinion is we’d rather invest money in tile than tillage.”
They’ve also noticed they’re not bringing as many rocks up to the surface as they used to when they tilled their fields.
“We very seldom have to pick up rocks. We’re not spending our summer with skid loaders picking up rocks all year,” Ben points out.
Early on, they compared yields from strip-tillage to the more conventional approach of chopping stalks and running a field cultivator twice over a piece of ground to create a smooth seedbed. The strip-tilled area yielded 10 bushels better.
“That was an easy transition to go to strip-till corn-on-corn versus full tillage,” Andy says. “The strips have worked really nice for us on those fields that are heavier and black.”
Cover crop benefits
Their first experience with cover crops was in 2013, when unrelenting spring rains prevented corn and soybean planting on thousands of acres in north central Iowa.
The Johnsons took what they learned that year, and have continued planting cover crops on about 70% of their acres to keep the ground covered through the winter.
They typically seed oats into standing soybeans in the fall, which provides good fall growth and eliminates worries about having time to kill the cover crop before planting corn the next spring. “Oats grow really well in the fall. It looks like your lawn out there after you combine beans,” Ben says.
They use a grain drill to seed cereal rye into corn stalks after harvest. Late harvests and wet weather the past two years have made planting cover crops a challenge and limited fall growth of rye, but the Johnsons are still noticing benefits the following spring.
“They seem to catch up and do a good job in the spring. You just have to be flexible with your plan,” Andy says.
The Johnsons say cereal rye helps suppress weeds in soybean fields, especially when it’s able to grow a few feet tall in the spring. They have experimented with planting “green” by waiting to kill the cereal rye until after soybeans have emerged, which resulted in improved weed control.
Cover crops, along with reduced tillage, have also improved water infiltration and benefited soil structure, Ben says.
“Our soils are firm. It seems like we can get going a day or two ahead of our neighbors in the spring,” he says. “In the fall, we can definitely get in a day or two before our neighbors.”
Research has proven cover crops can raise the organic matter of low-productive soils. The Johnsons are counting on the fact that they will also help maintain the organic matter in their highly-productive soils.
“I don’t want to start farming one that’s a six (in organic matter) and hand it to my kids at a 4,” Ben says.
Improving water quality
There’s also a water quality benefit, which is a key part of the Iowa Nutrient Reduction Strategy.
The Johnsons are participating in a new Iowa State University research project tracking how cover crops are helping reduce nitrate levels entering a wetland that drains water from 541 acres. Researchers have solicited farmers to plant cover crops and use reduced tillage on about 70% of the acres upland from the wetland, says Matt Helmers, director of the Iowa Nutrient Research Center.
In the first year of data, they noticed a significant decline in nitrates entering the research wetland compared to a similar wetland where conservation practices were not specifically targeted. A similar project is taking place in Story County.
“This project is one of the first of its kind where we’re trying to implement reduced tillage and cover crops within a (targeted) watershed,” says Helmers. “I would expect to see this treatment wetland to consistently stay below the control. All of our data at the plot scale shows tremendous nitrate reduction from cover crops.”
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