By James J. Hoorman, Hoorman Soil Health Services
Spring tillage warms the soil because each tillage pass reduces soil moisture by 0.5 to1.0-acre inch. It takes 10X more energy to warm up cold wet soil then air, so a tilled warmer, moist, well aerated corn seed may germinate faster.Â Tillage create good seed-to-soil contact for even and consistent corn stands and also kills early weeds which may reduce yields 10%.Â Tillage also burns up carbon and mineralizes soluble nutrients (50 PPM nitrates) for faster early corn growth. These early tillage benefits are the main reason why farmers do annual tillage.
The downside risks though are also a problem.Â Tillage causes higher soil erosion, soils start to seal as the soil organic matter is mineralized (40-60% loss in SOM in last 75 years), soils become tighter, harder to farm, less water infiltration, ponding water, and higher water and nutrient runoff. Weeds and other pests (insects and diseases) thrive on tilled soils, and generally more inputs (fertilizer, fuel, equipment, pesticides) are needed to get good yields.