No-till works in long run

Iowa Learning Farms partner Bill Hammitt grows corn and soybeans near Portsmouth in Harrison County. The western Iowa farmer started no-till planting corn in 1982, and in 1990 he built his first no-till, split-row soybean planter. He’s convinced long-term no-till has improved his soil structure and water infiltration.

“Our long-term no-till managed soils are like a sponge. We never see water standing in the terraced areas of our fields,” says Hammitt. “Long-term no-till fields really stand out as you drive around during a big rainfall event. Enhanced soil structure and earthworm tunnels at the surface really soak up rainfall. Unfortunately, even a single tillage operation can destroy the soil structure and soil health benefits of long-term no-till.”

Hammitt has partnered with Iowa Learning Farms since 2009. ILF works with many farmers across the state who use conservation farming practices while remaining profitable. These farmers help ILF by sharing their experiences with others to help build a Culture of Conservation in Iowa. They host field days, speak at workshops, or chat one-on-one with other farmers who are interested in making changes on their own farms.

All of Hammitt’s cropland is rotated between corn and soybeans each year. Minimizing the crop residue effect on seedling emergence starts with harvest of the previous year’s crop. Hammitt ensures that his combine straw chopper and spreaders are adjusted to provide uniform residue distribution and soil coverage.

Hammitt samples his soil by management zones and variable-rate applies dry phosphorus and potassium fertilizer prior to each crop based on crop removal of nutrients, management zone sampling and combine yield monitor maps. Nitrogen and sulfur fertilizers are supplied by multiple products and application timing; following soybean harvest, he surface-applies ammonium sulfate. Prior to corn planting he coulter-injects liquid UAN, ammonium thiosulfate and 10-34-0 liquid fertilizer to supply additional phosphorus for early seedling growth. Additional nitrogen is spring-applied as liquid UAN with preemerge corn herbicides.

No longer uses anhydrous

“Until about five years ago, we applied anhydrous ammonia as a less-expensive nitrogen source for corn, but we’ve noticed improved soil quality since we’ve moved away from anhydrous,” says Hammitt.

His planter has row cleaners and rippled coulters to plant corn in 30-inch rows. He raises the row cleaners and uses coulters alone when planting 15-inch soybean rows. Hammitt’s planter row units have standard rubber closing wheels.

Winter annual weed pressure can develop in fields with a long history of no-till. To combat winter annuals and development of glyphosate resistance, Hammitt uses several herbicide products. Herbicides offering residual weed control are a staple. Soybean weed management includes an early preplant application of 2,4-D to offer clean fields until June, when glyphosate is applied postemerge.

Hammitt has encountered winter annual weed pressure in corn. In response, after soybean harvest, he applies Basis herbicide with 2,4-D. For corn, a postemerge glyphosate application includes atrazine or another broadleaf-specific product to kill glyphosate-resistant weeds.

Hammitt has not experienced increased insect or disease pressure with long-term no-till. He uses soybean seed treated with fungicides and insecticides, and triple-stack corn hybrids with cutworm and earworm protection. Hammitt recognizes that corn disease resistance is important when selecting a corn hybrid, particularly for those planting corn following corn.

Hammitt serves on the Western Iowa No-Till committee. “No-till is about sustainability of the soil resource — for the next generation and for generations beyond. Here in the Loess Hills of western Iowa, no-till and terraces alone do not provide the full answer for long-term sustainability. I think cover crops may be the answer to help us build back soils that have been eroded and offer year-round coverage of the soil surface.”

Lundvall is with Iowa Learning Farms.

This article published in the May, 2012 edition of WALLACES FARMER.

All rights reserved. Copyright Farm Progress Cos. 2012.