Fabián Fernández, Department of Soil, Water and Climate at University of Minnesota, along with other researchers, compared soil properties after five years of no-till and strip-till to try to fill research gaps. Their findings were recently published in Agronomy Journal.
“We saw a consistent benefit of strip-till over no-till for these soils we were working with,” said Fernández. “In a previous study we measured a lot of crop parameters that indicated that strip-till allowed the plant to be more efficient in taking up nutrients and water and increasing yield. 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.”
The researchers looked at five specific soil properties: soil organic matter, penetration resistance, bulk density, water aggregate stability, and infiltration rate. The goal was to find out why strip-till was better at creating a beneficial environment for that crop to grow, Fernández said.
A major result was that after just five years, soil organic matter content was 8.6% greater in the strip-till plots when compared to the no-till plots. Furthermore, bulk density was reduced by 4% and penetration resistance, the force a root must exert to move in the soil, decreased by 18%.
“We know that soil organic matter is extremely important for a lot of properties in the soil, and we saw one of those benefits in terms of reduction in the bulk density of the soil,” he explained. “The soils were less dense and because of the reduction in density, we also observed less penetration resistance.”
However, there was no significant change in the water aggregate stability. This tests how stable the soil is against water erosion. The infiltration rate, which is how fast the water moves through the soil, was also unchanged. Fernández thinks these properties may form over time.
According to Fernández, the best place for strip till is in fields with a lot of crop residue and conditions that tend to be cool and wet in the spring and where farmers prefer not to do conventional tillage. However, researchers don’t necessarily know how every field will respond because there are a lot of tradeoffs. For example, Fernández doesn’t suggest that farmers use this method on sloping fields because the tilled crop rows can actually encourage erosion.
For those soils where strip-till would be appropriate, it can be a powerful method that benefits the soil by both working to help conserve soil and improving soil physical properties.
“These soil properties impact a plant’s ability to maximize its resources,” he 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.”