Shift application timing
Returning to the family farm outside White Hall, Ill., after working in agribusiness for four years meant Cox brought a fresh perspective to the row-crop side of the business. Her father, Ethan, gradually began turning over management of the 3,000-acre corn-soybean-corn-silage operation to Maria, the sixth generation to manage it. This allowed him to focus on their 100-head cow-calf herd and backgrounding enterprise.
"I looked at the things we had been doing well, including building grass waterways and buffer strips and using no-till systems on highly erodible fields," she says. "But I also began looking for things we could be doing better. My education and work experiences taught me to question everything."
She started by looking at when and how fertilizer was applied. Historically, most of the nutrients had been applied via commercial fertilizer and manure in the fall at a flat rate, based on crop removal levels. Working with Lake, Cox began implementing 4R principles to improve nutrient efficiency and minimize waste. They shifted much of the farm's commercial fertilizer application to the spring - a major decision, since many growers in Greene County on the state's west side still apply mos of their fertilizer in the fall," says Lake.
"The Cox farm now fall-applies nitrogen on only the first fields to be planted to corn in the spring, and they use split nitrogen applications, including a side-dress pass, on most corn fields," he adds. Those changes have improved nitrogen use efficiency from 1.5 to 1.2 pounds per bushel on many fields and to 0.9 pound per bushel on the most productive fields.
For Minnesota farmer Tony Rossman, grid soil-sampling and variable-rate fertilizer application have become his most important tools for maximizing efficiency and minimizing environmental nutrient loss in his corn-soybean rotation. Topography in his fields north of Rochester transitions from flat prairie to rolling hills, which requires a customized approach for each field and sometimes each acre.
"Spoon-feeding the crop when it needs nutrients is not always the most convenient management approach, since it often requires another pass across the field," he says, "but that's part of delivering nutrients at the right time for maximum plant uptake."
Despite variability from one growing season to the next, Rossman has seen yields climb consistently over the last five years since he bagan working with agronomists at CHS in Rochester, Minn., to put his 1,600 acres into CHS YieldPoint® services.
Rossman's crop nutrient use has become more efficient using satellite and GPS technology to gather field data and make site-specific applications. Based on soil test results, yild potential and previous yields by zone, he has potash and phosphates variable-rate-applied in the fall. Two-thirds of his nitrogen is spread preplant with a urease inhibitor and one-third is applied via side-dress, based on nitrate tests.
"By setting realistic yield goals, then fertilizing accordingly, we've seen average corn yields go up by 2 to 5 bushels per year," he says. "Soybean yields have increased, too."
His nitrogen use per acre has dropped as low as 0.8 pound per bushel, thanks to variable-rate technologies and split nitrogen applications, he notes.
Question every pass
Fall tillage is still fairly common in many parts of Illinois, but as she returned to the operation, Cox says she was quick to question whether deep tillage was necessary.
"My dad had been successfully no-tilling soybeans for years and it just seemed logical to build on that approach on our corn acres," she says. "By eliminating tillage passes, we're not only saving money but saving soil."
Aiming for a mostly no-till system, Cox decided to try strip tillage with ammonia application on several fields last fall. "It should deliver the best of both worlds, disturbing only one-third of the soil surface while creating a nice bed for corn to be planted into in the spring," she says.
"The fields had been planted to an oat cover crop and the row cleaners did an excellent job ahead of the anhydrous knives," recalls Lake. "There hasn't been much strip tillage done in our area, but it looks very promising."
For Rossman, whether he's planting on contours in fields with rolling hills or reducing tillage across his operation, he's also focused on conserving topsoil. "I've been working toward getting to no-till on as many acres as possible, but we still use minimum tillage and even some conventional tillage, based on field conditions and soil types," he says. "About one-quarter of our corn acres are no-tilled, but it's harder to make it work on heavy clay loam soils. It's definitely a process that will take time."
Evaluate cover crops
Dysart, Iowa, farmer John Weber is one grower who has worked with cover crops as part of the soil health equation. His early successes with cover crops have made him an advocate of the practice.
Weber reports he has seen the most success with cereal rye, which he now plants after corn on the 2,600-acre operation. "The practice works particularly well following seed corn, which is harvested early and allows more time for seeding a fall cover crop."
In just a few years of working with cover crops, Rossman says he's seen benefits including improved water infiltration and less runoff, especially during heavy rainfalls; increased organic matter levels; and less weed pressure from waterhemp and other species.
Satalite imagery and field mapping have helped fine-tune crop nutrient applications for Oronoco, Minn., grower Tony Rossman, right and his CHS agronomist Nathan Drewitz.
"Over the past four years, we've been fairly aggressive about using cover crops, including cereal rye, brassicas and turnips," he says. "We started by seeding after harvest on the 200 acres of sweet corn and peas we raise annually for a local canning plant, but have also begun flying cover crop seed onto corn stubble, hoping to get about 4 inches of growth in the fall. Ryegrass typically regrows 10 to 12 inches in the spring before we apply a burndown treatment."
His cattle graze cover crops in late fall. "They eat the grass and spread manure naturally. It's very sustainable and one more way our cattle enterprise brings value to the crop side," says Rossman.
In 2016, Cox first seeded cereal rye following corn on 25 percent of the farm. She was so impressed with the soil-holding benfits that she seeded fall rye on about three-fourths of the farm in 2017.
"The first spring after seeding cereal rye, when the rye was about knee-high, we had really heavy rains, dropping 10 inches within a few days," she recalls. "There was noticeable erosion on tilled fields, but none on cereal rye fields."
"We've also noticed improved weed control after using a cover crop, which saves a sprayer pass," she adds.
Water quality results
Both Rossman and Weber have monitored water quality as a means of measuring nutrient management success. With a river running through part of his Oronoco, Minn., farm, and as a cattle-and-hog producer who regularly applies manure to fields, Rossman says he has always been responsible about fertilizer use.
Along with using a nitrogen and knifing in manure to avoid odor issues and volatilization, he helped organize a small group of local producers who share information about sustainable best practices, including tillage strategies and cover crop use. The group's research led Rossman to enroll in the Minnesota Agricultural Water Quality Certification Program, a voluntary program of the Minnesota Department of Agriculture. He is working toward certification through the program, which requires taking regular water samples to monitor contaminant levels.
Planting cover crops and establishing grass buffer zones have helped Dysart, Iowa farmer John Weber minimize soil erosion and nutrient loss.
"I want to show the public that I'm using responsible stewardship practices on our farm, while measuring nutrient management efficiencies," says Rossman.
In Iowa, Weber stepped up to take part in a pilot program that included installing saturated grass buffers in on of his fields and testing wells to monitor their effectiveness. Installed by Iowa State University staff, the wells transmit collected data to researchers.
"That field has a long history of manure applications every other year ahead of a corn crop," Weber says, "so nitrate levels were high prior to buffer installation."
He adds his farm's monitor readings have improved since installing buffers. "Environmental stewardship doesn't have to come at the expense of production agriculture."
Learn more: Find more information at nutrientstewardship.org.
Check out the full C Magazine with this article and more.