Strip-Till Corn Yields ‘Intermediate’

By Ron Johnson Dairy Editor
Thursday, September 4, 2008 7:42 AM CDT

Corn growers looking for the highest possible yields will probably choose conventional tillage. Field trials consistently show that conventional tillage n moldboard plowing or chisel plowing n puts more bushels in the bin or tons in the silo than no-till.

Then there’s strip tillage. This method usually brings an “intermediate” yield somewhere between what conventional tillage and no-till produce, according to Joe Lauer, an agronomist at UW-Madison. Lauer talked about maximizing corn yields during the recent Midwest Strip Tillage Expo at the Arlington Agricultural Research Station.

Corn grown in conventionally tilled soil often yields 5 to 9 percent more than corn in no-tilled ground, Lauer said. In Wisconsin, the difference is more like seven to 10 extra bushels in favor of conventional tillage.

In a corn-soybean rotation, there’s virtually no yield difference between conventional tillage and no-till, Lauer continued. But with corn following corn, the yield difference can be as much as 17 bushels per acre in favor of conventional tillage.

Lauer has been looking at corn yields from four types of tillage for two years at the Arlington research station. Just north of Madison, the station is on deep prairie soils.

So far, two-year numbers show strip tillage slightly outpacing the other tillage methods. Strip-tilled corn at Arlington has averaged 223 bushels per acre.

Narrow band tilled

With strip tillage, a narrow zone of soil is disturbed. The zone is six to eight inches wide and six to eight inches deep. This tillage zone lies in what was the previous year’s crop row.

Another version of strip tillage uses a berm of soil. Berms are several inches higher than the surrounding parts of the field. The corn or soybean seed is planted in the berm, where soil temperatures are higher.

Strip tillage using berms at Arlington has averaged 218 bushels of corn per acre over two years, Lauer reported.

Chisel plowing has yielded corn averaging 219 bushels per acre at Arlington. No-till has produced the lowest average yield n 211 bushels per acre.

Advantages

Strip tillage offers several advantages over other tillage types. One, said Lauer, is a smaller yield depression when growing continuous corn.

For some reason, yields tend to slip a bit the longer continuous corn is grown. At Arlington, over the course of 17 years, the yield depression has amounted to 17 bushels per acre, Lauer said.

But with strip tillage the yield depression has been less n 15 bushels per acre.

Another plus for strip tillage is the amount of residue it leaves on much of the soil. This “trash” lessens erosion.

The residue also makes much of the field cooler, conserving moisture. But in the tilled area that gets planted, soil temperatures can be higher, especially if berms are made. This higher soil temperature n a few degrees at best n can speed germination.

And, this warmer soil around a young corn plant’s growing point can provide an important boost in terms of growth. Lauer said such warm ground is “setting the crop up for a higher yield.”

Lauer showed slides of conventionally tilled corn next to strip-tilled corn when both crops had tasseled. Both sections were planted on the same date and were the same variety and maturity. The strip-tilled corn stood noticeably taller.

That’s not unusual, according to Lauer. He commented, “You tend to have a little bigger plant” with strip tillage.

Interactions

Turning to hybrid/tillage system interactions, Lauer said any potential yield gain is “not significant.” So there’s really no need to try to match the corn hybrid to the tillage system.

“It’s very difficult to pick a hybrid for a conventional or no-till system,” Lauer said. Instead, he suggested paying attention to getting a good stand established.

Look at the field conditions and go according to them, he urged. “If the field is right, go ahead and plant,” the agronomist said.

Narrow rows

What about narrow rows for strip tillage? Yes, narrow-row corn can yield better, he acknowledged.

Even so, the yield premium might be as small as 5 percent, Lauer pointed out. And with narrow rows, “Where to you put the (previous year’s crop) residue?” he asked.

Population

When it comes to plant population, Lauer said there’s no need to increase it with strip tillage. The highest corn yields come at 38,500 plants per acre, he noted, while the recommended plant population is 28,000 to 32,000 plants per acre.

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