2010-10-22 / Farm News

Agronomist: Fall Tillage Often ‘Expensive Entertainment’

Purdue Report by Steve Leer

Farmers with extra time on their hands following a swift harvest should think twice before tilling more cropfields this fall, said a Purdue University agronomist.

As much as they might want to turn over black earth during what has mostly been a dry, sunny autumn, producers could find late-season tillage offers few benefits for the 2011 crop year, said Tony Vyn.

“Whenever you do recreational tillage, it is expensive entertainment,” said Vyn, a cropping systems specialist.

Except in certain situations, the potential negatives of fall tillage outnumber the positives, Vyn said. The downsides include a greater vulnerability to soil erosion, little to no crop yield improvement the following year and added expense.

“Substantially enhanced erosion susceptibility has a longterm cost,” Vyn said. “In the short term, with the combination of fuel prices, equipment costs and other expenses, a producer really has to analyze whether a tillage operation will contribute something positive to the bottom line of corn and soybean production on a given field.”

Purdue research indicates it does not. Studies conducted since 1975 on dark prairie soil near West Lafayette show that chisel and moldboard plowing provides no substantive yield advantage for corn following soybeans when compared with no-till systems.

Researchers recorded average yields for corn following soybeans from 2000 to 2009 after fall chisel plowing of 204 bushels per acre. Yields following fall moldboard plowing averaged 202 bushels an acre, while untilled ground yielded an average of 201 bushels of corn per acre. Purdue researchers also recorded small yield differences for corn following soybeans this year, Vyn said.

There also is little rationale for fall tillage on fields being planted to soybean the next year, Vyn said. Between 60 percent and 70 percent of soybean acreage in Indiana each year is already grown in a no-till system.

Fall tillage might make sense in a few cases where corn follows soybeans, Vyn said.

“About the only justification you can make for tillage when corn follows soybeans is if it enables an earlier planting opportunity on poorly drained fields,” he said. “If you need to do some tillage in order to have the soil warm up or dry out faster, you need to ask yourself, ‘What is the minimum amount of tillage that I need to do on that field, with the residue and drainage situation I’ve got?’ Some of the minimum tillage systems that might accomplish that goal with lower cost and less incorporation of protective residue cover include strip tillage and shallow vertical tillage.”

For corn following corn, fall tillage can noticeably increase yields in fields with medium- or fine-textured soil, Vyn said.

“It doesn’t need to be very intensive tillage or tillage that goes down to depths of 12-13 inches,” he said. “It can be as simple as a single pass of strip tillage, where it reaches a depth of eight or nine inches and forms berms between corn rows from this year so that it enables a stale seedbed planting system next spring.”

The average yield benefit for corn following corn from fall tillage compared with no-till has been tracked at 22 bushels per acre from moldboard plowing and 17 bushels an acre from chisel plowing, in 2000-2009 Purdue research. There was almost no yield difference between tilled and untilled continuous corn acres in this year’s results.

“There was, however, a huge yield reduction - about 35 bushels per acre - for planting corn after corn instead of soybean,” Vyn said.

For additional observations on fall tillage, read Vyn’s article, “Fall Tillage Decisions in 2010,” which appears in the Purdue Pest & Crop Newsletter. The newsletter is available online at http:// extension.entm.purdue.edu/pestcrop/ 2010/issue25/index.html.

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