Fall Zone Tillage Conserves Soil, Yields Well
Corn producers selecting a tillage system for poorly drained or high-clay soils in 1999 don't have to choose between conservation and profitability, says Purdue agronomist Tony Vyn. Fall zone tillage can give them both.
"With fall zone tillage you have as fast a rate of soil drying in spring as after fall chisel plowing, as well as the advantage of being able to plant on the loosened strips while keeping 30 percent residue cover for erosion protection," Vyn says. "Chisel plowing in fall uses more fuel, incorporates most of the soybean residue and requires one or two secondary tillage passes before planting."
Where it works, no-till saves farmers $15 an acre on input costs compared to chisel or moldboard plowing, Vyn says. But no-till has drawbacks for corn planted into high-clay or poorly drained fields, which make up nearly half of farm acres in Indiana. Kept in no-till, those fields take longer to warm up in spring. That can translate into later corn planting, which increases the risk of lower yields.
So, many U.S. farmers have fallen back on deep tillage before planting corn. In fact, while farmers planted more soybeans in no-till acres last year than the year before, the number of corn acres planted in no-till dropped. In Indiana, 54 percent of farmers have adopted no-till systems for soybeans, but only 16 percent use no-till for corn.
But they have another option, Vyn says. His research shows that new zone tillage methods and equipment used in the fall can give them profitability plus erosion protection.
Midwestern farmers who've tried the new system agree.
"We'd been no-tilling our corn for years, but there were springs when it took the soil a while to warm up and dry outand that was even true with conventional tillage," says Dan DeSutter, a farmer from Attica, Ind. "With fall zone tillage, the soil is drier and eight to 10 degrees warmer in spring. That gives us a two- to three-day advantage to get in and plant. Some years that's no big deal, but other years it means you can get in the fields in April instead of waiting until May."
Zone or strip tillage first was used when farmers added attachments to no-till planters as a spring conservation tillage method. During the last decade, farmers and researchers decided to try it in fall and saw promise in the new method. Vyn, who has spent 20 years researching tillage systems, has been working on fall zone tillage since 1993.
With fall zone tillage, farmers use implements that have shanks with narrow teeth, modified anhydrous knives, fluted coulters and/or ridging discs to prepare raised strips of soil for planting. Commercially available implements loosen soil to depths of up to 18 inches. Vyn's experience suggests there is no benefit to going deeper than eight inches.
Mole knives, one popular option, loosen soil to depths of about nine inches. When combined with ridging discs, these leave strips mounded three to four inches high. By spring those are two inches or less above surrounding soilbut that's high enough to dry and warm them for early planting and good yields.
DeSutter emphasizes that it's critical to form a good mound. He's had success using a mole knife with 18-inch smooth blade disc sealers.
With fall zone tillage, farmers also can use air delivery systems to band fertilizer (phosphorus, potassium and/or nitrogen with nitrification inhibitor) while they till, Vyn says.
While Vyn is sold on the new tillage system, he warns that it isn't perfect. "Farmers with manure to incorporate will find it a bit of a challenge," he says. "But there are tools out there that will allow both nutrient application and tillage in the same operation."