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Corn+Soybean Digest

Take A Second Look at NO-TILL

There's no room on Mike Clemens' farm for recreational tillage. With his no-till system the benefits are three-fold, says the Wimbledon,ND, grower of corn, soybeans and other crops:

  • “It saves me $20-25/acre in fewer trips through the field compared to conventional tillage.

  • “It conserves moisture, particularly from the hot drying wind that we get in North Dakota. That's very important to me since our rainfall averages about 18 in./year.

  • “It keeps valuable soil in place.”

Like many growers, Clemens increased his corn acres and he used a “modified no-till” system. He uses one tillage pass on the majority of his corn acres besides planting. In the fall, he strip-tills and in the same pass puts down nitrogen (N) and starter fertilizer. For his 2,000 acres of soybeans, he uses only one pass, period.

Clemens gives two examples that he says prove the value of his system. First, “there was no snow until late January (2007). You could see clouds of dust on the horizon from certain conventionally tilled fields.”

Second, “one summer, there was no precipitation from June 12 to Aug. 12, with several days in the upper 90s and some in the 100s. But my corn averaged just 10-20 bu./acre fewer than normal; soybeans 5 bu. fewer than normal. I was surprised. I expected yields about half of normal,” he says.

No-till offers a huge advantage against moisture losses on his clay and sandy loam soils, particularly from drying winds, he says.

Clemens made three main changes to make no-till go: Using heavy down-pressure springs on his planter to push the openers down, row cleaners to clear enough residue for proper seed placement and setting his combine in the fall for even residue distribution.

IN THE VIEW of some agronomists, more producers could make use of no-till systems to cut energy costs and conserve valuable topsoil.

However, no-till success depends on climate and soil factors. “There is no one-size-fits-all” tillage system, says Gyles Randall, soil scientist at the University of Minnesota. Poorly drained soils in the colder areas of the Corn Belt with high rainfall are poor candidates for no-till, he explains.

In Indiana, data show that 25% of corn is no-tilled and over 60% of the soybean acreage is no-tilled, says Tony Vyn, Purdue University agronomist.

“The economics are favorable for no-till for corn following soybeans,” Vyn says, “when you factor in $25/acre of savings by reducing trips through the field, even at $4/bu. corn. There is no way you can justify chisel plowing” economically. Long-term data show that no-till corn yields after soybeans are within 4 bu./acre of conventional tillage systems.

Vyn adds that strip-tillage is an option for growers who do not want to go all the way to no-till. “It gives them almost as much residue cover as no-till,” Vyn says. “My speculation is that as much as one-fourth of what we call no-till in Indiana is actually strip-till,” he adds.

For corn following corn, the data show that there is about a 12-bu./acre advantage in yield for strip-till relative to no-till on a loam soil with 2.5% organic matter, Vyn says, and a 12-bu./acre advantage for a chisel plow compared to no-till. “Extra trips through the field with the chisel plow and secondary tillage are not justified when strip-till yields are equal to those after chisel plowing,” Vyn says

UNIVERSITY OF ILLINOIS agronomist Emerson Nafziger does not believe that a switch to more corn following corn necessarily reduced the amount of no-till acres or left soils more vulnerable to erosion. In fact, he says, the switch to more corn “could be a slight positive, because it's more difficult to control erosion following soybeans than following corn.” He estimates that in Illinois, maybe 15-20% of corn is no-tilled — including strip-till — and 50-60% of soybeans.

In Iowa, overall, no-till is 17-18% for corn and 30-32% on soybeans, “not much different from five years ago,” says Mahdi Al-Kaisi, agronomist at Iowa State University. The percentage is much higher than average in southeast and southwest Iowa “where there is a lot of highly erodible land,” while much lower in north-central Iowa, which has wet, cold, poorly drained soils.

In Al-Kaisi's view, far more acres should be no-tilled, “but there are a lot of misconceptions about no-till, even with the technology we have. When you factor in all costs, it's breakeven in Iowa,” he says: a 4-5 bu./acre reduction in yield, especially in poorly drained soils, but with lower costs.

One of the major misconceptions, Al-Kaisi says, “is that tillage improves soil tilth.” It's quite the opposite, he says. No-till improves soil tilth and soil structure, and water is retained and transferred to plants.

Another misconception, Al-Kaisi says, is that crops should be cut close to the ground at harvest. Again, it's just the opposite, and cutting plants too close to the ground or removing crop residue defeats the purpose of no-till by not having enough residue for conserving soil moisture and reducing soil erosion.

Al-Kaisi says, however, that no-till in corn following corn is more challenging, which creates a tendency for farmers to want to use conventional tillage. He adds that farmers are successfully using no-till in corn following corn, so it can be done.

That said, Al-Kaisi explains that farmers going to no-till in corn following corn “need to do their homework.”

He says there will be a different response by soil type. On well-drained soils there will be little difference in yield response, and possibly a 5% difference on poorly drained soils.

In the glacial-till soils of south-central Minnesota that tend to be cold in the spring, “our data does not support no-till on continuous corn” because of severe yield reduction, says Minnesota's Randall. He estimates that no-till is used on 10% of soybeans in southern Minnesota and just 1% of the corn, primarily due to frozen soils and cooler springs that growers don't have farther south in the Corn Belt. No-till on continuous corn in an 11-year study showed a 20-bu./acre/year disadvantage. And yield difference worsened with time.

A better argument can be made for corn following soybeans, however, with 6-10 bu./acre difference in yields over 30 site-years of experience in south-central Minnesota. Where Randall sees a lot of opportunities for no-till growth, however, is in soybeans following corn.

He adds that his research does support no-till for corn following soybeans on the well-drained loess soils of southeast Minnesota. In this part of the state, no-till for corn still is less than 5%, “but could be higher,” Randall says.

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