Crops - The Lynch File: Ontario's silent revolution in tillage

Tuesday, February 16, 2010

More growers are doing more tillage of corn stalks before they plant soys, partly because of the change in headers. They want to avoid no-tilling soys into a mat of corn trash

by PAT LYNCH

Over the last couple of years, tillage in Ontario has gone through a quick and silent change. There was no big announcement about it.

These days, more growers are doing more tillage of corn stalks before they plant soys. Part of this is a result of the change in corn headers. The newer headers are chopping stalks more than the older headers. And some of the newer combines are equipped with stalk choppers. This header change has resulted from growers wanting to plow shallower. But it also affects no-till soys.

Combines equipped with stalk choppers are not new. There was a lot of activity about stalk choppers on headers in the early 1990s. In the '70s, stalk choppers were used as a separate pass to facilitate plowing.

Growers used to no-till soys into corn stalks which were mainly standing. The newer headers mean growers are no-tilling soys into a mat of corn trash. Generally, growers who no-tilled soys into a heavy residue saw a significant yield reduction in 2009 on most soils.

This difference in yield of no-till versus tillage is not new, but the extent of the difference seen in 2009 has never been so great and will probably not be seen again. Long-term research in Ontario comparing tillage systems shows that crops planted on soil that is worked, out-yield crops that are no-tilled. This is true for corn soys and wheat.

The exceptions are on soils where the extra trash at the soil surface retains moisture. In this case the yield decrease is offset by the advantages of no-tilling. This past year, growers have told me they got eight to 10 bushels an acre more where they worked the soil. This yield difference more than pays for the extra cost of tillage.

The big change in Ontario's tillage system is tillage that leaves more trash on the ground than conventional plow and cultivate tillage. Collectively, you can call this a reduced tillage system (RTS). One company has used this RTS acronym quite successfully in their brands of tillage equipment. There has been a lot of talk about "vertical tillage."

Simply put, this vertical tillage is really a reduced tillage system. 

All of these various tillage systems allow good soil mixing, without bringing up sub-soil and stones. They also allow seedbed preparation without strikeouts and dead furrows, and are much quicker than the plow and work systems.

When discussing no-tilling wheat into soy stubble, we used to talk about the drill being out of the field before the combine. Now, it is the tillage tool being out of the field before the combine. While the combine is unloading the last load of corn, the tractor and disc, or other reduced tillage tool, is finishing the field and leaving.

Another thing affecting this change in tillage is the difference in corn stalks today compared to 15 years ago. Today's corn hybrids have more lignin, a component of the plant that makes the stalk stand better.

This lignin has a side-effect. More growers have been noticing that the residue from today's hybrids is hard on tires. The lignin in today's hybrids make the stalks razor sharp.

I spoke with one grower who had to have the press wheels changed on a new drill one season after the drill was purchased, because the corn stalks had shredded the rubber on the press wheels.

This change in tillage is gradual and incomplete. It is not occurring on every field. There are fields that will yield higher without tillage. These are the fields with lighter soils and with shallow topsoil above bedrock. But if you have a custom combiner, it's best to look to see how the stalks were left. You may need to do some tillage next spring. 

For next year, if you do not want your corn stalks chopped as much, talk to your custom combiner. Just because there is a stalk chopper on the combine does not mean it has to be used. BF

Pat Lynch, CCA (ON), is an agronomist for Cargill in Ontario.