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Consider History When Contemplating Fall Tillage

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A Purdue Extension agronomist says fall tillage decisions this year and in any year should be based on the short and long-term effects of that tillage on their fields and not the in-season phenomena like drought in 2012.

Tony Vyn says a farmer’s natural reaction to a drought year is disappointment, and that may lead to what he calls “revenge tillage.” So when making this year’s tillage decisions consider this year but also recent history.

“And so the recommendations are let’s limit our tillage operations first of all by asking the question do we need any tillage at all? For many Indiana soils in a corn-soybean rotation we simply don’t need to do tillage, or if we need to do tillage it would only be perhaps something that is limited in depth and perhaps width, as in for instance a strip tillage operation.”

Tillage loosens and rearranges soil aggregates with the intent of establishing a better foundation for crop seed placement and root growth, but the drought itself has already accomplished deep cracking and loosening of some soils. The drought also reduced the post-harvest crop residue that is often used as an additional justification for tillage. So in what fields might tillage be useful this season?

“Where we need perhaps fall tillage the most is in corn following corn on poorly drained soils. Where we need tillage the least is certainly corn-soybean rotations on well drained, sandy soils. Where there is the greatest risk of tillage is always on fields that have the highest and longest slopes and where there is the greatest risk of soil erosion loss.”

“Tillage has a permanent effect that can forever change soil water-holding capability on slopes,” Vyn said.

Additionally Vyn recommends that farmers consider limited fall tillage for fields with a history of compaction, high clay content, lack of systematic drainage or fields with very slow-drying soils.

“I don’t want farmers to overestimate the need for fall tillage just because of the 2012 drought and poor crops,” he said. “It’s important to adopt a tillage system that leaves topsoil uniformly in place to build up a whole field’s resiliency in root-zone water retention over time.”

He urged farmers to exercise caution and always be aware of the soil loss risk, saying they should examine soil conditions and crop yields over a number of years when considering tillage.

“The early harvest may promote fall tillage, and the disappointment factor may further motivate farmers to till ground,” Vyn said. “But often we don’t know how an individual year’s yields would have changed with more or less tillage.”

Normally, the protective residue cover and greatly reduced soil disturbance associated with no-till mean less evaporation loss and higher soil water availability to roots. But this year, no-till fields did not provide as much protection against the drought as expected.

The early-season onset of high temperatures and lack of rain limited both root growth and shoot growth in 2012. Corn and soybean varieties differ in their relative rooting ability under stress conditions, but rooting in all varieties after the early seedling stage depends on energy reserves coming from shoot growth.

“The near-surface soil was so dry, lack of tillage meant more resistance to root penetration, meaning corn or soybean plants in those fields sometimes experienced more drought stress before flowering than other tilled fields, despite the crop residue cover,” Vyn said. “But we may never see such a severe, early drought occur with that combination of timing and high temperatures again.

“A later-season drought occurring after deep early root establishment would have favored no-till more.”

If farmers decide to practice fall tillage, they can choose from several management techniques. Standard primary tillage procedures include using a disk, chisel plow, deep ripper, moldboard plow or strip tiller.

Vyn said agronomists favor strip tillage because it allows for minimal soil mixing and residue incorporation while preparing fields for earlier seeding of spring crops, and it can be combined with fertilizer application.

“It’s a proven, versatile tillage practice that creates a warmer, drier zone of soil in the spring that ensures timely seed placement in both corn-soybean and corn-corn rotations,” Vyn said. “Precision automatic guidance systems have also simplified crop row placement in the center of the loosened strips.”

He said there’s still time yet for farmers to decide whether fall tillage is needed for their fields and that they shouldn’t rush the decision. With fall rains, farmers should be cautious and not rush fall tillage on soils that may be too wet.[audio:https://www.hoosieragtoday.com//wp-content/uploads//2012/10/whether-to-fall-till-this-year.mp3|titles=whether to fall till this year]

Source: Purdue Ag Communications