Less Is More

Bin-buster corn yields in the Midwest were far from the norm in 2019 because of adverse weather, but Curt Mether had one of his best crops ever.

The Logan, Iowa, farmer credits 20 years of no-till production. Mether farms in the Loess Hills region of the state, an area not known for flat and black productive soil that produces monster yields. He initially abandoned tillage to prevent soil erosion but improved yields, and lower production costs were added bonuses.

Despite persistent precipitation that delayed planting in 2019 for most farmers in his area and a dry spell that August, the Harrison County farmer's corn yields ranged from 220 to 280 bushels per acre (bpa), about 10 bushels better across the board than 2018. The county average in 2018, the last year recorded by the U.S. Department of Agriculture (USDA), was 176 bpa.

Soil structure, soil health and organic matter gradually improved over time by not tilling and adding cover crops, Mether says. Water infiltration and holding capacity improved, as well, and soil compaction is rarely a problem. All these attributes aided
his 2019 crops, Mether asserts.

"We didn't have a (yield) disaster like others," says Mether, chair of the Iowa Corn Growers Association. "Last year, it seemed like it rained every other or every third day, but we could plant and do other field activities in a more timely manner; and plant health was good."

Some farmers in Mether's region who actively till struggled to get crops planted on time, if at all, in 2019, and crop performance suffered. He adds conventional-till fields were often muddy on top and didn't let water soak in, unlike his fields.

Mether suggests producers consider no-till or conservation tillage, if they haven't already, as a way to increase production and the bottom line.

"It wasn't all no-till in 2019 with better herbicides and genetics, but it played a big part," Mether says.

TILLAGE STUDY

A recent Stanford University study indicates conservation tillage and no-till will likely improve corn and soybean yields over time.

Research led by Jillian Deines, a postdoctoral scholar at the university's Center on Food Security and the Environment, shows Midwest farmers who used conservation-tillage practices from 2005 to 2016 increased corn and soybean yields on average by 3.3 and .74%, respectively. Any tillage and planting system that covers 30% or more of the soil surface with crop residue falls in that category, according to the USDA.

The report, "Satellites Reveal a Small Positive Yield Effect From Conservation Tillage Across the U.S. Corn Belt," was published in December 2019.

Farmers till the soil for a variety of reasons -- to control weeds, incorporate nutrients, create a smooth, warm and dry seedbed, and break up compaction -- to maximize yield potential. But, conventional tillage, which fractures the soil several inches deep and can incorporate most or all of the previous year's crop residue, damages soil structure, can contribute to nutrient loss and leaves topsoil vulnerable to wind and water erosion. It also takes time and money.

Deines foresees her team's research findings giving farmers confidence to try to increase no-till and conservation tillage.

"The research suggests that in most cases, farmers worried about the yield impact of conservation tillage don't need to be," Deines says. "It can be a win-win practice -- better soil health, better yields and cost-effective."

Stanford researchers used machine learning and satellite data sets to identify areas of reduced and conventional tillage, and to quantify the effects on crop yields. They focused on all or parts of nine states: Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, South Dakota and Wisconsin.

Conservation tillage practices accounted for 54.2 million acres in U.S. corn and soybean production in 2018, according to Operational Tillage Information System data supplied by The Nature Conservancy and the Conservation Technology Information Center. In 2006, it was 55.1 million acres.

Deines says tillage systems need to be tailored to individual farms. There are instances and areas where conventional practices, such as chisel-plowing or disk-ripping, are needed. While the study found an average yield benefit to conservation tillage, the study showed it reduced corn and soybean yields in some fields by 1.3 and 4.7%, respectively.

"There's good evidence that sticking with it [conservation tillage] will pay off in the long run," Deines says.

Mether is active in The Nature Conservancy's 4R Plus program, which pairs conservation with nutrient stewardship. No-till production isn't easy, he admits. Planter setup and the right nutrient and herbicide programs are essential to get strong plant stands and growth. Cold soil in the spring from crop residue can also be a challenge, which can delay planting and emergence.

Farmers are often cautious and so yield-focused that changing tillage practices is difficult, Mether says.

"The [Stanford] study may help change that attitude," he adds.

SOIL SAVINGS

It will take corn farmers 11 years to see the full yield advantage of conservation tillage, according to the Stanford study. When commodity prices are low, limiting tillage can provide an immediate financial benefit, explains Aaron Daigh, North Dakota State University assistant professor of soil physics.

Less fuel, equipment, labor and maintenance are associated with reduced tillage, he says. A tillage pass, depending on the implement used, can cost $12 to $30 per acre, he explains.

"When farmers can eliminate one or more tillage passes and not have a yield loss, and eventually increase yields, that's more money in their pocket," Daigh adds.

DILIGENT DATA

Stanford's yield findings are "beautifully consistent" with Daigh's tillage research. However, he says farmers sometimes question field- and region-specific research.

What's powerful about Stanford's work is its scope, Daigh contends. It examined tens of thousands of farms and acres across the Corn Belt.

"One of the most common questions I get is, 'I live in the next county over and have a little different soil, do you think this translates?'â??" he says. "[The Stanford study] gives farmers confidence what we see in tillage research, as far as yields, is the norm from North Dakota to Ohio."

FOR MORE INFORMATION:

> Satellites reveal a small positive yield effect from conservation tillage across the U.S. Corn Belt. Visit iopscience.iop.org/article/10.1088/1748-9326/ab503b

> Follow Matthew Wilde on Twitter @progressivwilde.

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