While soybean growers have been moving toward no-till in a big way, the growth of no-till corn acres has remained somewhat flat in recent years.
In fact, some farmers have never tried no-tilling corn because they’re unsure of planting in ground covered with residue, says Alan Sundermeier, a Henry County (Ohio) county agricultural extension agent.
Plowing gets residue out of sight and allows other farmers to plant corn easily. But they lose many no-till benefits, including highly valuable residue cover.
Strip-tillage may offer a solution for no-till corn growers, say Sundermeier and Randall Reeder, an agricultural engineer with Ohio State University (OSU). You can use a strip-till machine in the fall to move residue away from the row and create a strip or ridge of bare soil. The exposed soil in the ridge warms up faster in the spring, allowing for earlier no-tilling of corn.
In fact, soil temperature in a strip-tilled seed zone can be 6 to 10 degrees warmer on sunny spring afternoons than untilled areas between the strips. This zone reaches the same temperature as quickly as the soil found in a conventionally tilled field, says Reeder.
The areas between the strips are left untilled and covered with residue, which conserves soil moisture and reduces erosion. It also helps build soil organic matter and soil structure.
Set It Right!
Reeder recommends using a strip-till machine with a row cleaner in front, which moves residue away from the row where the strip will be made. It should have a coulter to cut through residue and a shank (or mole knife) to cut a narrow slot through the soil. It should also have a pair of discs at the back. The discs hold 100 percent of the soil in the strip area to build a small 2- to 4-inch tall ridge.
“If you operate this equipment without those discs, you won’t be a strip-tiller, but you’ll be a ditcher,” says Reeder
Strip-till usually works the soil 6 to 8 inches deep, says Reeder. Deep placement of phosphorus and potassium is common, while many strip-tillers also apply anhydrous ammonia. But applying anhydrous ammonia can present problems early in the fall, says Reeder.
The soil should be 50 degrees or cooler to minimize nitrate loss. This creates a conflict because strip-till should be done early in the fall to reduce weather risks while nitrogen application should be done in late fall. The best option may be to apply most of your nitrogen after the no-till corn crop emerges next spring, says Reeder.
Sundermeier has collected strip-till data from both research and private farms in northwestern Ohio over the last 3 years. Three consecutive springs have been ideal for no-till, which is unusual for this area.
In Sundermeier’s tests, strip-till gave a slightly quicker, more uniform emergence than other systems. However, all of the systems tested had the same final stand count and by harvest time, there was no yield difference.
At the OSU experiment farm in northwestern Ohio, Sundermeier and his colleagues compared three tillage systems: chisel plow, strip-till and no-till. They buried continuous recording thermometers to get a precise picture of soil temperature and seed emergence.
They analyzed data for a 24-hour period on a clear day in late April (a key time for no-tilling corn in this part of Ohio). The strip-till system’s seed zone was cooler at night while the no-till system and the chisel plow system (which had 30 to 50 percent residue) were about 5 degrees warmer.
“You lose some energy with strip-till during the dark hours, but when the sun comes out, strip-till shoots right back up and bypasses the other systems,” says Sundermeier. “By mid afternoon, we saw an 8 to 10 degree temperature difference.”
Achieving a soil temperature of 50 to 55 degrees F is necessary for corn germination. With other tillage systems, the soil might not be warm enough by this date to trigger germination. A day or two of sunshine and subsequent soil warming is what would help strip-till stand out from the other systems.
Sundermeier set out to quantify soil moisture in the different systems. He collected soil cores from 2 inches down in the seed zone. In both soybean and wheat residue, the strip-till system had the driest soil. “We did this when we thought conditions were right for planting,” he says.
Following With Soybeans
What happens when you follow strip-till corn with soybeans? Will fertilizer concentrated in bands affect soybean performance?
It depends a great deal on your soil, Sundermeier suggests. On one of the Ohio farms he studied, all fertilizer had been deep placed during strip-tilling. Potassium levels were higher in the old corn row area where the fertilizer had been applied 15 inches to the side of the row.
If potassium levels were low between the rows, that could affect soybean performance. Since most Ohio farms have adequate phosphorus and potassium levels, no-till soybean plants between the strips should not show any nutrient deficiency.
Reeder says strip till can help protect crops against adverse conditions. Jim Kinsella, a no-tiller from Lexington, Ill., who has strip-tilled for many years, considers strip-till good insurance policy in cold, wet weather.
It paid off in 1996, for example, when Kinsella’s strip-tilled corn yielded 15 to 22 bushels per acre more than no-till corn following a cold wet spring.
Strip-till can also help you control diseases in your no-tilled crops, such as pythium. Wayne Pedersen, a University of Illinois plant pathologist, observed problems with this disease in no-till. Pedersen frequently observed losses (due to pythium) of at least 10 percent in no-till stands.
He views strip-till as a solution to a disease problem. Over several years of testing, Pedersen saw strip-tilled ground yield an average of 204 bushels per acre of corn compared to 177 bushels per acre for no-till. The difference was primarily attributed to lower plant stands with no-till.
University of Minnesota soil scientist Gyles Randall conducted a 3-year study, comparing strip-till, no-till and chisel plow systems. Strip-till yielded an average of 4 to 6 bushels per acre more than no-till and about 1 bushel per acre less than chisel plowing.
However, in springs where there is no weather disadvantage to no-till, strip-till is less likely to show a yield advantage, says Tony Vyn, Purdue University agronomist.