Effect of Tillage System on Soybean Production.

The adoption of continuous no-till cropping systems has been limited in the poorly drained upland soils of southeastern Kansas. Soils generally consist of a shallow topsoil (less than 30 cm), overlaying a dense clay-pan subsoil. Soybeans (full-season and double-crop) represent a major cash crop for this region of the eastern Great Plains. Typically, full-season soybean is rotated with corn or grain sorghum to diversity cropping systems, and double-crop soybean follows after wheat harvest. This research evaluates the long-term effects of tillage method on full-season soybean yield when soybean is grown in rotation with corn or grain sorghum in a 2- or 3-year crop rotation at two sites. Tillage treatments were: 1) plant all crops with conventional tillage (CT), 2) plant all crops with no-till (NT), and 3) alternate CT and NT systems. Soybean yields over an 8-year period have varied with year and location. Initially, soybean yields were greater with CT than NT. In recent years, however, soybean yields with continuous NT have been equal to or greater than CT. Soybean yields for NT following CT (alternating tillage) have been significantly lower than those for continuous NT or continuous CT. Results indicate that soybean can be grown successfully using NT conservation practices in shallow upland soils, although a yield drag may occur during the initial stages of NT adoption.