By Scout Nelson
Soil health depends on protecting the soil from excessive disturbance and keeping the soil surface covered. Two important soil health practices are reducing tillage and leaving crop residue in the field. No-till systems and residue cover can help protect soil, conserve moisture, and support better growing conditions.
Hans Klopp, SDSU Extension Soil Health Field Specialist, explained the value of reducing soil disturbance and keeping crop residue on the soil surface. These practices can help improve soil structure, protect water supplies, and support long-term soil health. They can also help farmers manage the effects of dry weather and changing field conditions.
Conventional tillage removes much of the protective residue from the soil surface and exposes darker soil. Dark soil absorbs more sunlight, so it warms faster and can remain warmer during much of the growing season. This is especially important before crops develop a full canopy.
Warmer soil and increased oxygen from soil disturbance can speed up the breakdown of organic matter. Over time, this can lower soil organic matter and reduce the soil's ability to hold water. Tillage can also break apart soil structure and damage the natural pores created by soil organisms and weather cycles.
Soil pores are important because they provide pathways for water to move into the soil. After a dry summer, large cracks can develop in the soil. Rain and melting snow can move quickly through these cracks and enter the soil profile. When tillage damages natural pore networks, water infiltration can decrease, which may reduce the amount of water stored for future crop use.
Tillage can also affect soil moisture by increasing evaporation. Warmer, uncovered soil loses more water to the air. Leaving residue on the surface provides a simple way to reduce this effect.
Crop residue offers several benefits for soil health. Residue adds organic matter and nutrients to the soil as it breaks down. It also provides a protective layer between the soil and sunlight. Because residue is usually lighter in color than bare soil, it reflects more sunlight and reduces heat absorption. This helps keep the soil cooler and reduces moisture loss.
Residue also helps protect soil from heavy raindrops. Direct rainfall can break down soil aggregates and create a hard surface crust. A crusted soil surface may have fewer large pores connected to the surface, making it harder for water to enter the soil.
Healthy soil also contains many living organisms. Earthworms, bacteria, fungi, and other organisms help create channels and pores within the soil. These pathways support water infiltration, drainage, and water storage. Keeping the soil covered can create better conditions for these organisms.
Research from South Dakota supports these soil health benefits. A study near Brookings found that keeping corn residue in a corn-soybean rotation increased soil organic carbon, soil water retention, and soil water content during the growing season. The improvements were observed after 10 years of residue retention compared with removing residue. The study also found greater water infiltration and more plant-available water where residue remained in the field.
A long-term study near Beresford found that soil moisture was higher during much of the year under no-till management than under conventional tillage. Soil organic carbon was also higher in no-till systems.
Researchers also collected additional data in May 2026 at the SDSU Northeast Research Farm near South Shore. The two-year study compared no-till, fall strip-till, spring strip-till, and conventional tillage systems.
In soybean residue, soil water near the surface was lower in spring strip-till rows and conventional tillage areas than in no-till areas or between strip-till rows. At depths of 3 to 6 inches and 6 to 12 inches, soil water did not differ among the tillage treatments.
In corn residue, soil water was lower within fall and spring strip-till rows than under conventional tillage, no-till, and areas between strip-till rows. Soil moisture under conventional tillage was similar to no-till because the plots had been disked only one day before sampling.
Additional soil health measurements from the study will provide more information later.
Photo Credit: gettyimages-zoran-zeremski
Categories: South Dakota, Crops, Sustainable Agriculture