By ANN HINCH
INDIANAPOLIS, Ind. — Does a no-till system benefit corn and soybean yields in Indiana, or is conventional tillage the way to go? One Purdue University professor sees a middle ground – namely, the raised berms from strip-tilling in the middle of otherwise undisturbed rows of untilled soil in a field.
Extension agronomist Dr. Tony Vyn talked to a roomful of attendees of the annual National No-Tillage Conference earlier this month about strip-till or, as he described it, the best alternative to no-till.
The timing of strip-tilling berms in the fall for spring corn is critical, he said, because their height will mellow down under frost and other general winter conditions. He suggests going to a depth of 7 inches and leaving a berm of 3-4 inches high, to begin.
“Often, the biggest advantage is one of more planting availability,” he said, if not necessarily yield gain. “I believe that there’s a big future in strip-till in those situations where no-till is risky because of planting dates.”
He explained strip-tilled rows may buy a grower more days if they have concerns in the spring about planting delays because of field drainage problems or the size of their planting equipment.
Strip-tilling in high residue in a corn-after-corn or corn-after-wheat system usually does provide a yield advantage over no-till, Vyn said; for corn after soybeans, though, higher yield with strip-till is not a certainty.
“I’m still a student of tillage systems,” he explained of his research, adding strip-till has been aided greatly by precision planting technology – not just in getting the seed more precisely in the center of the berm months later, but in delivering inputs within a precise distance of the seed.
As an example, he said it’s important to deliver the right amount of nitrogen pre-planting – as in, not too much, if any. Too much can fry the corn, rather than aid it – “You can lose plants, and you can lose plant yield,” Vyn said.
Recently he tested amounts of pre-plant nitrogen application in a strip-tilled corn system on two test plot locations in northern Indiana. Both plots received a total of 200 pounds UAN 28 percent per acre, just delivered in different methods.
For instance, one section of corn received no pre-plant UAN and the 200 pounds was all sidedressed after seeding, while other sections received varying amounts of pre-plant, such as 50, 100 or 200 pounds of UAN.
What he found, overall, was the more pre-plant nitrogen that is delivered, the further away from the seed it’s helpful to place it. The no-pre-plant corn yielded as well as that getting all 200 pounds pre-plant – approximately 200 bushels per acre in this particular test – if the UAN was placed 10 inches to the side of the seed.
Corn receiving the full amount pre-plant at the same location as the seed yielded about 60 bushels fewer per acre. The best yield in this test, though only marginally above the 200-bushel mark, seemed to be 50 pounds of pre-plant UAN delivered 5 inches beside the seed, with the other 150 pounds sidedressed.
Other research conducted at the University of Illinois over two years has tested whether deep-banding phosphorous and potassium with the seed may boost strip-till corn yield; Vyn said there seems to be no advantage to this over a broadcast application of P and K. There was, however, an average 10-bushel gain per acre in both over no-till broadcast.
He did say he sees an advantage to banding P with corn in colder and earlier planting situations. He personally prefers injected P because of water-quality concerns. With K, he worries about banding too much in the berm because it could hurt the corn, so he might recommend banding some and broadcasting the rest as needed.
With soybeans, Vyn said the study didn’t show much impact on banding with strip-till over broadcast for strip- and no-till, perhaps a gain of just 1-2 bushels per acre. He also doesn’t see much yield advantage in strip-tilling soybeans after strip-tilled corn.
In the Hoosier State last year, Vyn said all corn showed its biggest percentage drop from the state’s yield trend line in 150 years, at about 38 percent, thanks to the drought. The anticipated yield was 164 bushels per acre but the trend line was closer to 100.
The month of May gave growers precipitation close to normal, but as the summer stretched on, growers well remember that the rain did not. Vyn said this seemed to put more stress on no-till corn than strip-tilled fields, the latter of which he said had less leaf rolling and better height.
On May 2 last year, he said the height of both types were roughly the same; a month later, the strip-till corn was taller. In fact, he said Indiana strip-tilled corn last year did as well as that planted in chisel-plow fields, and better than in fall-till systems.
Vyn said he believes the timing of the drought was a key factor in the noticeable success of strip- over no-till in 2012, explaining if the drought had started in July instead of May, no-till corn would have fared better.