URBANA, Ill. — Results of a five-year study show that strip-till methods outperformed no-till by improving the soil’s physical properties.

In general, strip-till methods may be the best choice in the Midwest because of the climate, explained lead researcher Fabian Fernandez, assistant professor of soil science at the University of Minnesota. The study looked at both corn and soybeans and found similar results for both.

“No-till has very important benefits, but it doesn’t work in every situation everywhere. The Midwest has colder and wetter springs. With no-till, the plant residue is a barrier to the soil warming up and drying, causing a delay in planting. A delay can reduce the yield potential,” Fernandez said.

The University of Illinois study showed an 8.6 percent increase in soil organic matter after just five years. Further, bulk density of the ground was reduced by 4 percent, lessening the soil’s penetration resistance by 18 percent.

Penetration resistance is the measure of how hard the root must work to move in the soil.

In a previous study of corn and soybeans, Fernandez found that strip-till resulted in better yields and efficiency in taking up nutrients and water when compared to no-till.

“So then we decided to look at the soil physical properties that may be changing in response to these tillage methods to see if we can explain why we’re seeing these benefits in the crops,” Fernandez said.

Tillage practices 

Fernandez said that the best place for strip-till is in fields with a lot of crop residue and wet, cool spring conditions where farmers prefer not to do conventional tillage.

However, he cautioned that every field is different with a lot of trade-offs, and researchers don’t necessarily know how every field will respond. For example, he said strip-till on a sloping field would not work well because the tilled crop rows can encourage erosion.

A till doesn’t just chop up the soil; it also blends dead plant material left from harvest into the soil and exposes wetter soil to the air, loosening it. Some soils respond well to this.

In conventional tillage, the entire field is turned over, while in a strip-till field, only the crop rows are tilled, leaving the spaces between undisturbed. However, a warmer, drier soil is more prone to erosion and moisture loss. No-till leaves residue that protects the soil from erosion and moisture loss. Places like Argentina, where Fernandez is from, use strict no-till with success, he said.

“Strip-till is a hybrid of strict no-till and conventional tillage. It combines the benefits of the two,” Fernandez said.

Strip-till has been in practice for about 25 years, but studies that reveal the science behind different tillage practices are lagging behind.

Agronomy Journal recently published the results of this study. Associate editor John Guretzky explained why he published it.

“I try to find studies that show good, innovative science. What caught my eye is that this study compared different tillage methods, which has been an important topic for a long time – how crop growers manage the soil.

“No-till is often promoted as having strong benefits … but this study shows producers can still get the benefit of plant residue between the rows and enhance the growth of crops with strip-till,” Guretzky said.

Some drawbacks

Fernandez said that strip-till is not the answer for all situations.

“The results of the study show that strip-till outperformed no-till. That’s important to remember, but at the same time, I wouldn’t say it’s the best in every situation,” he added.

Fernandez said that strip-till has its drawbacks when compared to conventional tillage.

“I try to be balanced. I see many benefits to strip-till, but there are issues. Compared to conventional, strip-till requires more skill and technology, such as a guidance system like RTK (Real Time Kinematic). Also, there is more time commitment with strip-till.”

Fernandez said he and fellow researchers from the University of Illinois (U of I) were not surprised by the results of the study. 

“We did a previous study beginning in 2007, which showed better yields in strip-till. So, the only surprise is that we saw the same results for both corn and soybeans. It is often more difficult to get a response from soybeans,” he said.

More research needed

A former assistant professor at U of I, Fernandez said strip-till is growing faster in Illinois than in Minnesota. He said that strict no-till, in which fields are not tilled at all, is not practiced much in the Midwest.

“Strict no-till in the true sense is not used a lot in the Midwest because farmers use no-till with soybeans and till for corn every other year,” he said.

Fernandez said more long-term studies on the effects of tillage on soil are needed. He would like to see the five-year study he has done extended to 10-20 years.

“It’s important to continue studies on the long-term to see the effects in the soil over time,” he said.

While the five-year study revealed improvements in organic matter, bulk density and penetration resistance, it did not show significant change in water aggregate stability, which tests how stable the soil is against water erosion. Infiltration rate, which is how fast the water moves through the soil, was also unchanged.

Fernandez’s hypothesis is that these soil properties would also change over an extended time.

“These soil properties impact a plant’s ability to maximize its resources,” Fernandez explained. “If you can get these soil properties to an optimal level, they can allow the plant to grow with more ease, allowing it to focus its energy on yield.

“I’d really love to see further research happen. A lot of good information came out of these studies,” he said.