Max Dunseth, Scotia, IL, was skeptical of Nu-till, a "systems approach" to crop production. Nevertheless, he cautiously phased in the system. He says it uses planter attachments to manage crop residue while providing good seed-to-soil placement, better timing and better nutrient placement.
The result for Dunseth: up to a 10% increase in corn yields on clay soil. "We've maintained yields on our flat, black ground," he adds.
Nu-till relies on three essential elements: air and water management, nutrient management, and tillage and planting equipment, according to Ag Spectrum, a DeWitt, IA, crop input supplier and farm management company.
For Dunseth, maintaining or increasing yields was important, but not his only consideration. He wanted to reduce machinery costs and comply with soil and water conservation requirements.
"Our goal was to find a system to address our highly erodible land and avoid the need for two sets of machinery," he says. "We didn't want to have one system for conventional tillage and another for conservation tillage."
Yields are now more consistent across all fields, says Dunseth. His corn averaged 205 bu./acre in 2003 and 202 bu./acre in 2002. Soybeans averaged 47 bu./acre last year and 57 bu./acre in '02.
"Nu-till works best on our marginal, highly erodible ground," he says. "We don't see as much of a yield boost on our flat, black ground, but we still meet our yield goals with fewer trips and less machinery; plus fuel, phosphorus (P) and potassium(K) savings."
Since 1995, Dunseth has used Ag Spectrum's CleanStart pop-up fertilizer, which is supposed to maximize kernel production. He also uses the system's microbial enhancer, called GroZyme, which releases nitrogen (N), P and K from existing crop residue at planting.
He one-pass plants and fertilizes in spring on about one third of his acreage. On the other two thirds, he plants on top of a fall anhydrous ammonia application. He also sidedresses additional nitrogen where needed while applying postemerge herbicides.
Two university extension soils scientists are skeptical of the products. University of Minnesota's George Rehm and South Dakota State University's Jim Gerwing advise farmers to use generic starter fertilizers. Both see no problem with the mechanical portion of Nu-till, yet neither has seen evidence that adding a microbial product such as GroZyme at planting will improve yields.
"The good parts of the Nu-till system are the use of fertilizer at planting, moisture conservation and conservation tillage," Rehm says.
Nu-till creates more root structure that buffers the plant against stresses and produces a larger ear," says Jerry Hatfield, director of the National Soil Tilth lab, Ames, IA. "We've been using 100-120 lbs. N/acre with Nu-till and getting the same or better yields compared to 150 lbs./acre with conventional systems."
In 10 Iowa research locations over the past two years, Hatfield compared Nu-till to fall strip-till, fall chisel and spring till (full-width tillage, one or two passes). He says fall strip-till and Nu-till have so far helped improve crop performance, particularly in dry conditions. Both outyield fall chisel and spring-till fields by 5-10 bu./acre.
Scott Staggenborg, Northeast area extension agronomist at Kansas State University, says row cleaners and seed firmers help establish plants and give uniform stands. Starter fertilizer containing 30 lbs. each of N and P will add growing season length to corn and sorghum crops, he adds. And soil temperatures in strips are 4-5° warmer than soil covered with residue during late April and early May.