Primary tillage systems differ in their impact on soil and crops as well as the amount of time and resources they require. Tillage may loosen soil, incorporate nutrients, warm or dry soil, manage weeds, bury residue, or level the surface for subsequent operations. Variable soil and weather conditions may result in different decisions about the need for tillage even within similar soil types. A three-year experiment compared corn and soybean yields among subsoil, chisel plow, striptill, and no-till systems on Webster silty clay loam soil.