As the adoption of no-till practices has spread widely across parts of the U.S. over the past few decades, the approach has been touted as an important means of storing carbon in soil—and a key solution to solving the climate crisis.
But despite its recent growth in popularity, “no-till” has no single, agreed-upon meaning. In fact, the phrase is often a misnomer. Most no-till farmers have not cut out tillage altogether and do not engage in other beneficial practices such as planting cover crops. As a result, these “seldom-till” farmers aren’t able to permanently store carbon in their soil.
That trend, coupled with the scientific uncertainty on how to measure and verify carbon sequestration, could throw a wrench into the Biden administration’s plan to fund an agricultural carbon trading program (or “carbon market”) as a central response to climate change.
“The reality is that 100-percent-never-till is [practiced on] a very small percentage of the acres across the United States,” said Steve Swaffer, executive director of No-Till on the Plains, a nonprofit that hosts an annual conference for no-till farmers in the Great Plains region. “There’s certainly a need to change this.”
Herbicide Availability Spurs No-Till Movement
Tillage has been an intrinsic part of global agriculture for thousands of years. Breaking up soil helps clear land for production and quickly uproots and kills weeds. Tilling also aerates and warms the soil, buries plant residue, incorporates fertilizer or compost, and creates a clean, level bed to make seed planting easier.
Some farmers adopted limited soil conservation practices in the aftermath of the Dust Bowl—caused, in part, by intensive tillage practices—but most continued to plow up their fields multiple times every year. It wasn’t until the 1970s that farmers in the Midwest, the Plains, and the Southeast began switching in earnest to no-till and reduced tillage practices, spurred by the widespread availability of broad-spectrum herbicides, including glyphosate (the main ingredient in Roundup), and later by the genetically modified crops resistant to those herbicides.
In some cases, chemical companies such as Imperial Chemical Industries, which developed the controversial herbicide paraquat (also known by its brand name Gramoxone), conducted no-till experiments and helped spread the concept of reduced soil disturbance.
Liberated from the need to plow for weed control, farmers who grew commodities such as corn and soy began to spray them with herbicides and parked their tillage equipment to cut down on fuel and labor costs—a much-needed relief during the energy crisis of the 1970s and the farm crisis of the 1980s.
Today, the no-till movement continues to be concentrated in regions that grow commodity crops with the use of chemicals: states with the highest no-till adoption rates include Montana (73 percent of all acres), Kentucky (68 percent), Tennessee (79 percent), and Virginia (74 percent).
The practice has also gained favor with farmers looking to switch to so-called regenerative practices—either as a way to build healthy soil and reduce input costs, or because the company they sell their crops to is in some way incentivizing the change. General Mills, for instance, has committed to converting 1 million acres to regenerative practices and Danone, Walmart, and a number of other large consumer packaged goods (CPG) companies have taken on similar initiatives—meaning that many farmers are making the change to meet the demands of the marketplace.
According to the 2017 U.S. Census of Agriculture, the number of the farms practicing intensive tillage declined by 35 percent between 2012 and 2017. The number of farms practicing reduced tillage increased by 11 percent. And while no-till farms increased by less than 1 percent during the same time period, the number of no-till acres has continued to increase.
No-till Is a Misnomer; Conservation Tillage, an Oxymoron
On the ground, there’s ample evidence suggesting that the vast majority of no-till farmers occasionally or regularly return to tillage, calling into question the environmental benefits and carbon-absorbing potential of their soils.
A study by the U.S. Department of Agriculture’s (USDA) Economic Research Service found that while nearly half of all corn, soybean, wheat, and cotton acreage was identified as no-till or strip-till (tilling small areas of fields to prepare seed beds for planting) at some time over a four-year period, only about 20 percent of these acres were identified that way for the whole duration.
The terms “reduced till” and “minimal till” can also mislead. They’re both undefined versions of the generic “conservation tillage,” which denotes a wide range of systems that leave at least 30 percent of the soil surface covered by crop residue after planting. In practice, this often means a farmer has slightly reduced the number of tillage passes or simply switched from a moldboard plow—the most aggressive tillage practice—to a chisel plow, a slightly less destructive one.
One former USDA researcher even called “conservation tillage” an oxymoron that “gives a misguided sense of entitlement and conservation,” despite the fact that many of the practices under its umbrella lead to “significant soil loss” and hence are not sustainable.
Reasons No-Till Farmers Return to Tillage Are Complex
Factors such as climate, soil type, crop type, cultural convention, family dynamics, and a limited understanding of how soil works may influence a farmer’s decision to take up the plow again, soil health experts say.
Many no-tillers in the Midwest return to tillage on a regular basis, or alternate between years. Others strip till or till in a way that only disturbs the top two inches of soil, while still others will upturn their entire fields, said Swaffer with No-Till on the Plains.
Some farmers say a changing climate is making it difficult to stick with no-till. Justin Topp, who grows a number of grains and legumes on 14,000 conventional and 1,500 organic acres near Grace City in North Dakota, told Civil Eats that the short growing season in his area means untilled soil isn’t usually warm enough to plant seeds into. And then there’s the erratic weather: It was so wet in 2019, he said, that he had to till his fields in order to aerate and dry out the soil—otherwise, his crops would have failed.
On the other hand, this winter was so dry that he’s planning to convert some of the previous year’s minimum-till fields to complete no-till to retain moisture. (Topp has also tried inter-seeding a rye cover crop with the corn, but it failed to grow both during the wet and dry years.)
“I would love to switch to 100 percent no-till all the time,” said Topp. “We’re trying. But it just doesn’t work. . . . We have to make the best decision for our farm year after year.”