How to tweak a long-term no-till system
Growing up, Brad Zimmerman loved everything about his family’s corn-soybean farm near Groveland, Illinois.
“I didn’t want to go to school,” he says. “I just wanted to ride with Dad in the tractor.”
Even at a tender age, he took to planting his own crops, using buckets for fields. Flowers and vegetables – he’d try to grow anything.
As a young adult, he wanted nothing more than to be a part of the family farming operation, which, at the time, included his father, uncle, and grandfather. “There wasn’t room for me on the farm, so I went to college and worked away from home,” he says.
That changed when his father, Phillip, died in 2013. Zimmerman brought his own young family back to the farm soon after. He became the sole operator on a downsized farm comprising 300 acres. He farms additional acres with a partner.
When he took over his home farm, the soil was already in pretty good shape.
“Dad was an early adopter of no-till,” he says. “He liked to see residue on top of the ground, and he liked the fact that this provided a type of armor for the soil. The soil structure and water infiltration on our farm were good.”
Zimmerman, though, believed the soil could be even better.
“I’ve always been a science nerd,” he says. “I studied biology in college. I’m passionate about it. I wanted to take Dad’s no-till/strip-till system a step further. I knew when I started farming that the soil is a living organism and that the biological life in the soil is what makes it soil instead of just dirt. I wanted to find ways to improve the biology in the soil.”
Attending seminars and watching videos set Zimmerman on the path to self-educating about soil health. Finding ways to tweak his father’s system soon followed. In recognition of his efforts to improve soil, Zimmerman was named a Soil Health Champion by the National Association of Conservation Districts.
Modifying fertilization practices was his first change. Believing that anhydrous ammonia potentially has negative effects on soil life, Zimmerman quit applying anhydrous in the fall when strip-tilling for the next spring’s corn crop. He continues to apply dry fertilizer – phosphorus and potassium – in the fall.
“I’d like to eventually get away from broadcast fertilizer and put everything that the plant needs in the furrow to supplement what it gets from the soil,” he says.
In spring, he applies 60 pounds per acre of liquid nitrogen behind the planter.
Then Cover Crops
In 2014, Zimmerman started growing cover crops. His current practice is to no-till a cover crop of cereal rye and rapeseed into corn stubble in late fall. While the rapeseed has struggled to establish a good growth when seeded that late in the season, Zimmerman believes it offers potential benefits worth pursuing.
“Rapeseed has a taproot that can help break up compaction, and it also has properties that may fight soybean cyst nematodes,” he says.
To give the cereal rye and rapeseed cover crop a longer growing period in fall, Zimmerman plans to begin interseeding it into the corn when the crop is knee-high.
“My reasoning is that the cover crop could get established by the time the leaves of the corn shade the ground,” he says. “The cover crop would go dormant then. But it would grow again when the corn leaves dry down and start to fall. The cover crop would, theoretically, get a month’s head start and produce more growth in the fall.”
The following spring, the cereal rye stands 8 to 12 inches tall when Zimmerman no-tills soybeans into the green crop. He terminates the rye several days after planting the soybeans.
Reduced crusting of the soil at the surface is one benefit of growing the cover crop. As a result, soybean seedlings have better emergence, giving Zimmerman opportunity to reduce the seeding rate.
“In the past, we planted soybeans at a rate of 150,000 seeds per acre,” he says. “I presently plant 100,000 seeds per acre. I estimate a savings of $15 an acre in seed costs by reducing the seeding rate. That nearly covers the $17-per-acre cost of the cover crop seed.”
Soybean yields have increased, as well.
“We about stopped growing soybeans because we couldn’t seem to get more than 56 bushels an acre in yield,” he says. “But last year our soybeans yielded 84 bushels to the acre.”
A cover crop mix planted into the soybeans prepares the ground for corn. This multispecies cover crop includes annual ryegrass, radishes, turnips, and crimson clover.
“I use annual ryegrass in this blend instead of cereal rye because I like to mix things up with species,” he says. “Besides that, while cereal rye has a great root system, annual ryegrass has a phenomenal root system. Annual ryegrass doesn’t seem to tie up N like cereal rye might. When I plant corn into cereal rye, the corn will turn yellow. I don’t see that with annual ryegrass.
“Another reason I like annual ryegrass is that it doesn’t bolt in the spring like cereal rye does,” he says. “Annual ryegrass produces a steady growth that doesn’t get out of control as quickly.”
Zimmerman aerially applies the cover crop mix to standing soybeans after the leaves start to turn yellow but before they drop. The seeding typically happens in early September.
Overall, the cover crops have contributed to a lessening of weed pressure in Zimmerman’s fields.
“We used to have a lot of trouble with marestail,” he says. “But marestail hasn’t been much of a problem lately.”
like slicing into Chocolate Cake
Most importantly, the soil has changed – for the better.
“The soil is mellow and easy to plant into,” says Zimmerman. “When I put a shovel in the ground, it feels like it’s going into chocolate cake. I find earthworm middens and bugs when I disturb the residue. I find arthropods that are eating weed seeds and making channels.
“I’m so happy with our soil,” he says. “It’s filled with life and promises us a good future.”
Adding cover crops to his father’s longtime no-till system was Brad Zimmerman’s first step to further improve soil. Now, he hopes to add a cereal crop like winter wheat to the corn-soybean rotation.
“After harvesting the wheat in early July, we could plant a 12-way mix of cover crop and let it grow all summer,” he says. “I’d like to put as many roots into the ground as I can.
“Then maybe we could graze that with cattle and take advantage of their manure,” he says. “I’m excited to see the results five years from now.”