The Rademacher farm in Gifford, Ill., leapt into no-till with both feet after experimenting with planting cover crops and foregoing tillage. Starting in 2016, they’ve deployed the strategies together on all 570 acres they farm.
“We were lucky enough to have some pretty good growing seasons those first few years, which helped with yields,” Frank Rademacher says, referencing the yield drag that farmers usually experience after transitioning from conventional tillage to no-till. Warm springs in 2016, 2017 and 2018 spurred microbes to mineralize and free up nitrogen from the abundant residue for young corn.
“We’ve just had a great benefit from the whole system, and with good years on our side, we didn’t run into as big of a dip in yield as others who made the switch had,” Rademacher says, crediting the success to the cover crop component of the two-pronged conservation system.
Pete Fandel, agriculture professor at Illinois Central College and a Metamora, Ill., farmer, says in the first three to seven years a farmer transitions from tilling to no-till, field trial data shows a yield slump. But that drop in yields can be at least halved with the use of cover crops.
“Your yields are going to fall off when you transition to no-till. That slump you’ve got is a change in species of the microbial population. As some are dying and you’ve got these new ones building up, that’s where you hit that slump,” says Fandel, who uses cover crops on his no-till farm.
“Once the new guys build up, that’s when your yields start to come back up,” he says. “With cover crops, you will still have a little bit of a slump, but it will be much less steep, and it’ll bounce back faster.”
When it comes to controlling the ratio of “good” microbes to “bad” during the transition to no-till, Fandel says cover crops help shift no-till land to helpful microbes faster because they promote better drainage.
“Cover crops promote the good bacteria and fungi, not necessarily the bad ones,” he says. “In transitioning from tillage, your soil structure has to rebuild. With cover crops, the soil structure will re-form faster, which then helps with drainage. That then limits the population of harmful microbes that cause root rot problems.”
Tillage kills most fungi — whether they be harmful or helpful — and promotes a higher population of bacteria, Fandel explains. That population then spreads across the full surface area of residue and hastens decomposition. But cover crops bring in more beneficial fungi and bacteria by giving them living roots to thrive on outside of the growing season. Without those roots, the shift in microbial population in no-till systems happens more slowly.
While chopping residue is an option to help with decomposition ahead of the next growing season, hesitant farmers still fear the residue will hold too much moisture in the soil, stalling planting and taking away valuable growing degree units.
“I’ve found on my own farm that once you get your microbial population shifted over to where they love this new environment you’ve created for them, residue becomes a non-issue,” Fandel says.
Fandel must have at least 30% residue after planting to meet Natural Resources Conservation Service guidelines on his highly erodible ground, but in 2018, NRCS “dinged him” for not having enough — even though he rarely tills.
“It was soybeans no-tilled into last year’s cornstalks with cereal rye and rapeseed cover crop there all winter,” Fandel says. “I should have had massive amounts of residue after I planted, but because my microbial population has shifted so much to microbes that are good at breaking down residue, along with an earthworm population that’s geared up so much, I had less than 30% residue.”
He says NRCS was happy to “un-ding” him after investigating and seeing the old rows of corn and biomass from cereal rye. There was no trace of tillage.
“Cover crops end up solving a lot of your problems. The microbes and your earthworms are eating this residue as fast as I can produce it,” Fandel concludes.