Sometimes, no matter how hard you try, things just don't work out.
That appears to be the case for farmers in the northern Corn Belt who have tried to get consistent corn yields with no-till. Cold, wet spring soils offer too much of a challenge most years.
Frustration over no-till's performance on corn has farmers looking at strip tillage as an alternative. The system offers many of the benefits of no-till but can match the yields of conventionally tilled fields.
"We started seeing activity with strip tillage two years ago," says Gyles Randall, University of Minnesota soil scientist. "It's a good alternative to no-till in that it keeps residue on the surface and provides a very friendly area for seed placement and early growth."
With strip tillage, farmers till narrow strips in fields, preferably in the fall, and leave a 6- to 8"-wide band (4-8" deep) of soil that warms quickly in the spring. Some have modified anhydrous toolbars to create their strips. Or, several manufacturers make units to do the job.
"The effect on soil temperature from this system is dramatic," reports Wayne Pedersen, University of Illinois plant pathologist.
"In our university test plots, we've created a planting zone that is five to nine degrees warmer than regular no-till, making it comparable to conventional mulch-till," says Pedersen. "By late afternoon you can see as much as 12 degrees difference between strip-till and no-till."
The Minnesota researchers strip-tilled in fall, then experimented with fall- and spring-applied N. Fall-applied anhydrous ammonia was knifed into the strips about 8" deep. Spring-applied anhydrous was knifed in, at about the same depth, midway between the 30" rows.
Final results were a toss-up.
"You didn't need a plot plan to tell the difference," says Randall. "Early growth clearly favored the fall treatments. But by harvest, the spring-applied plots had caught up."
In the Illinois plots, all fertilizer applications were made in spring. Liquid nitrogen was broadcast with herbicide ahead of planting and was followed with starter at planting. In these tests, the fall strip-tilled plots clearly outyielded the spring plots in 1996 and 1997.
"In 1997, fall strip-till plots actually had the highest yields of the study," Pedersen says. "Spring strip-till was not as effective as fall strip-till, but better than no-till."
When Windom, MN, farmers Tom and Steve Muller and their father, David, first looked at strip tillage, they knew they wanted to get it done in the fall.
"We weren't even tempted to do strips in the spring," says Tom Muller. "It's too muddy. We'd just be asking for problems."
The Mullers built their own 12-row, 30" strip-till machine so it could apply dry P and K through an air delivery system, as well as anhydrous ammonia.
"We use a mole knife, similar to a subsoiler point, mounted on an anhydrous shank with a coulter in front," says Muller. "The units have 18-inch closing disks behind. We end up with a strip eight inches wide, six to eight inches deep and a ridge six inches high. By spring it settles down to about two inches.
"We're headed into our fourth year of strip tillage and are really pleased with the way it works," he add. "It gives us a bed of black soil to plant into in the spring. It's exciting."
To cover more acres last fall, the Mullers started strip-tilling fields and applying just P and K while the soils were still warm. When the soils cooled in late fall, they applied anhydrous as well.
"On the fields that just received P and K, we'll go back and make a spring application of nitrogen," says Muller.
It takes a different mentality to farm with strip tillage, Randall points out.
"You can't just harvest a field in the fall and turn your back on it," he says. "You're preparing your spring seedbed in October. After building your strips in the fall, the only thing left to do is put down herbicide and plant in the spring."
And, Randall adds, you need to rethink your equipment. As with no-till, you can eliminate a lot of your machinery inventory.
Randall doesn't foresee any problems with keeping planters centered on the tilled strips.
"There's less resistance in the strips, and the soft soil tends to pull the planter into them. It tracks automatically," he says.
"Our experience is that you almost can't get off the strips in the spring," adds Muller. "The planter really wants to follow those soft strips. We have trash whippers on our planter, but I'm not sure we need them. They may help sometimes.
"It's important that you do an accurate job in the fall, because it's hard to make any adjustments with the planter. We use row markers to make sure our strips are accurate."
An added benefit to the strip tillage system for the Mullers is a lower fertilizer bill.
"We use to broadcast fertilizer. By banding it under the rows we've been able to cut back our application rates, particularly P and K, and save about $10 an acre," Muller says.
"So far, we haven't seen any yield loss."