HOLDING ONTO HIS INVESTMENT IN NITROGEN
Farming 1,900 acres of rolling fields around St. Johns, Mich., by himself, Lee Thelen survives on efficiency and attention to detail. He’s always on the lookout for new tools to help, whether it’s a new hybrid in one of the variety trials he hosts with his wife (an Extension educator with Michigan State University) or a piece of equipment that improves the speed and accuracy with which he applies his inputs.
One thing that clearly bothers Thelen is wasting resources. Every year, he spreads 3,000 to 5,000 tons of manure – some from his 50 head of cattle, most from nearby cattle operations. It’s all part of his commitment to building soil organic matter and creating an environment in which his crops can thrive.
Thelen manages both cash crops and cover crops to ensure that the manure’s nutrients stay in the field’s root zone rather than flowing off the field into the Great Lakes watershed or leaching toward the groundwater.
“If you’re going to spend $100 an acre to put that manure on, you want to get the most you can out of it,” Thelen says. “We’ll apply manure in the spring and put corn right after to try to use up that nitrogen. If we put out manure in July or August, we want to hold it ‘till next May. What we’re trying to do is hold that nitrogen up to the surface all winter in the structure of a growing plant. I’d like to hold that nitrogen in the top 10 inches of the soil instead of letting the snow and the rain move it down three feet deep.
“I love the idea of holding onto our nitrogen so I have the chance to use it again,” he says. “A cover crop of wheat can hold about 20 pounds of nitrogen at the surface in growing tissue. If you’ve got 20 pounds of nitrogen out there, that’s $10 you’ve saved. Wheat and rye don’t die off over the winter, so they actually hold it for the next crop.”
Thelen also plants some tillage radish as a cover crop, drilling six to eight pounds of seed along with a bushel of oat or wheat seed to keep costs down. The decomposing radishes – Thelen calls them “carcasses” – hold nutrients and moisture into the spring.
“With radish, you’re able to sequester seven to 12 pounds of nitrogen up near the surface,” Thelen notes. “We get quite a bit of organic matter, which helps a lot, and more water-holding capacity in the sand, which helps early in the season. In heavier soils, you’ve got that taproot to give you some tillage.”
Timing matters, especially in central Michigan’s short growing season. Planted after wheat harvest in July or early August, he says, the taproots grow as big around as a man’s forearm. Seeded at the end of August, Thelen’s radishes only get about the size of a carrot.
Building Organic Matter
Thelen lets the radish taproots do the tillage he doesn’t have the time or inclination to do. He’s spent the better part of the past three decades building the soil – and building his one-man operation – with no-till. Over the past 15 years, he’s added cover crops to the mix, using a variety of plants and tactics to restore healthy microbial communities in his soils and boost the cash crops that follow.
The foundation, he says, is soil organic matter.
“If we rent your farm tomorrow, chances are your organic matter is about 1.6 to 1.8,” he says. “You give me five or 10 years and I’ll take it into the threes.”
Boosting organic matter improves soil moisture-holding capacity and increases fertility, says Thelen, which is valuable. But the microbes that make up the living fraction of soil organic matter are what he calls “the credit card part: priceless.”
As microbial activity increases, soils stop crusting, crop residue is digested into more organic matter, and soil structure improves. “It drains well, it farms well,” Thelen says. “We keep up with our neighbors who do all kinds of tillage.”
In fact, Thelen likely pulls far into the lead when it comes to profitability. No-till allows him to keep equipment and fuel costs to a bare minimum.
“We put 110 hours on my big tractor last year,” he says proudly. “The other one, we put 65 hours on it. We spray 3,500 or 4,000 acres with a sprayer that goes 65 hours a year. That sprayer’s going to last forever at that rate.”
He points out that his average fuel consumption is below two gallons per acre all season long. A 72-acre tiling job pushed the figure up – but even running a hefty tile plow through the summer only raised his average to 2.2 gallons per acre.
Thelen budgets about $5,000 a year for tests and experiments, his way of constantly looking for better ways to farm. Last year, he dedicated two fields to a cover crop seeding trial as part of the Great Lakes Cover Crop Initiative. The Initiative promotes cover crops that improve yields and reduce the flow of excess nutrients into the Lake Michigan, Lake Erie and Lake Huron watersheds. Comparing the biomass of various cover crops seeded at two-week intervals on Thelen’s farm will help Extension educators and the Conservation Technology Information Center (CTIC) hone recommendations to help area farmers select the optimum varieties of cover crops and integrate them into their operations.
Side-by-side trials are standard practice for Thelen, who encourages growers to experiment with cover crops on their own farms, in their own conditions.
“Try something simple. Try something complex. Just try something,” he says. “You could even try a couple of bags of leftover corn. Whatever you do, just make sure you have a benchmark to compare it to – see if you’re winning or losing.”