Multiple-year corn-yield champ, David Hula, Charles City, VA, and his family have no-tilled corn and soybeans continuously since the early 1980s and haven’t turned back. Without tillage, crop yields are higher and production costs are lower, says Hula, who farms with his father Stanley and brother Johnny.
“My dad and granddad, Stanley Sr., started no-tilling corn in the late 1960s as a way to cut costs,” says Hula. “When they didn’t see a yield reduction, they expanded the practice to more acres and more crops.”
Hula’s continuous no-till system, which he calls “never-till,” rotates corn with wheat and double-crop soybeans before going back to corn. “We are 100% continuous no-till on all of our acres,” says Hula. He admits that no-till corn works better on their sandier, well drained soils, which he plants first.
Never-till makes it possible to farm several different crops intensively for high yields and still reduce expenses, says Hula. “We don’t need as much equipment or manpower as we do with a plow and cultivator,” he says. “We farm about 5,000 acres with only one 250-hp tractor, which uses about 1.5 gal. of fuel/acre.”
Last year, Hula’s non-irrigated corn entry ranked fifth overall in the National Corn Growers Assoc-iation yield contest, at 319.32 bu./acre. In 2008 and 2007, Hula’s entries ranked second and first overall with 361.92 bu./acre and 385.59 bu./acre yields, respectively, in irrigated fields.
Yet, controversy remains over whether never-till can work well in the cold, wet climate of the northern Corn Belt.
“Soil moisture and temperature are the main factors in the success of continuous no-till corn,” says Paul Carter, agronomy sciences manager for Pioneer Hi-Bred. “For the drier western Corn Belt, leaving crop residue on the field helps to avoid some drought stress by conserving soil moisture for later in the season.”
Carter is one of three authors of an extensive literature review entitled “Influence of Tillage on Corn and Soybean Yield in the United States and Canada.” It compared existing research studies’ yields of no-till to conventional fall-tillage systems in corn and soybeans, finding a negligible national average yield difference between no-till and conventional tillage. No-till tended to have greater yields than conventional tillage in the South and West. The two tillage systems had similar yields in the central U.S., and no-till typically produced lower yields than conventional tillage in the northern U.S. and Canada.
No-till had greater corn and soybean yields than conventional tillage on moderate- to well-drained soils, but slightly lower yields than conventional tillage on poorly drained soils. Corn and soybean yields tended to benefit more from crop rotation in no-till compared to continuous cropping.
“The challenges to no-till corn in northern climates shows the importance of strong hybrid stress emergence and reducing risk from cold, wet soils,” Carter says. When selecting hybrids for northern growing zones, he advises first looking at yield performance and then examining “high-residue suitability ratings.” Northern no-tillers should also use the best-available residue spreaders on combines, the best seed treatments and the best planters for high-residue fields, Carter says.
Alternatives to no-till are strip-till and ridge-till systems, which directly target the soil-moisture and cold-temperature challenges in northern climate zones, he says.
Other experts argue that strip-till and ridge-till could be unnecessary and even detrimental to long-term soil and plant health and crop yields. “Compared to every other tillage system in Nebraska, properly managed continuous no-till wins every time,” says Paul Jasa, Extension engineer, University of Nebraska-Lincoln. “For us, it’s a no-brainer; if you want to be profitable, you should be no-tilling continuously, whether it’s corn, soybeans, wheat or grain sorghum. Yields will typically increase the first year no-till is tried in western Nebraska and over time in eastern Nebraska. To make no-till optimally successful, make it continuous,” he adds.
Even though the Conservation Tillage Information Center (CTIC) classifies strip-till as a valid no-till practice, Jasa contends that strip-till fails to measure up to continuous no-till. “Better soil-moisture conservation and healthier soils through better soil structure are the keys to the higher yields with long-term no-till compared to strip-till,” he says. “When it comes to nutrient and water uptake, plants have far better rooting when there’s crop residue on the soil.”
Because growers in Nebraska typically don’t have excess water, continuous no-till routinely increases yields here, notes Jasa. However, “Where you have excess water, you’ll have to intensify your cropping system in order to use all the water that no-till helps conserve,” he says.
“There are several ways of doing that, such as cover crops, double cropping, relay cropping and including winter annual crops and perennial crops in the rotation, which allows you to grow something different during parts of the year when water is available,” Jasa adds.
Without intensifying the cropping system, the soil-moisture savings become a hindrance rather than a help in wetter environments, says Jasa. “The people who disagree with us about the benefits of long-term no-till are the ones still planting corn and soybeans exclusively,” he adds. “Corn and soybeans only require about 18-20 in. of water/year for maximum transpiration. So, if you get more water than that, odds are you’ll complain that cold, wet soils are decreasing your yields, when it could be that your cropping systems aren’t being employed optimally to use all the water available to them.”
Farther north, Gyles Randall disagrees. He is University of Minnesota soil scientist at the Southern Research & Outreach Center, Waseca. “We see a yield disadvantage for both corn and soybeans when we look at continuous no-till systems in our area, where soils are frozen from early December to late March and residue decomposition over winter is minimal,” he explains. “Unless we have some rotational tillage, such as disking of corn stalks ahead of soybeans or a spring cultivation of soybean ground ahead of corn, at least once every four years, yields will decline.”
Other research results on continuous no-till for southern Minnesota show that “we don’t see the yield suppression on the well-drained, silt-loam soils like we do on poorly drained soils,” says Randall, and “long-term, the benefits from continuous no-till come more from soybeans than from corn.
“On erosion-prone, highly erodible soils or sloping, well-drained soils, you can get the best yields and the best conservation benefits by no-tilling soybeans after corn,” he adds. “That is clearly the most opportune time and placement for continuous no-till in our area.”
While rotating to more crops than corn or soybeans could be beneficial for a continuous no-till system in southern Minnesota, success with cover crops is more of a challenge, says Randall. “Cover crops in Minnesota are difficult to establish, due to our cold fall soil temperatures,” he says. “They also don’t synchronize very well with farmers who want to plant corn as soon as possible in the spring.”
August 2010