Conservation Soybean Production Systems In The Mid-Southern Usa: I. Transitioning From Conventional To Conservation Tillage

The adoption of production systems that leave greater than 30% residue coverage on the soil surface, that is, conservation tillage, is limited in the mid-southern United States due to the development of a hardpan and subsequent yield reductions. This research was conducted to determine if the inclusion of subsoiling in conservation tillage systems can maintain yield and profitability relative to that of conventional tillage. The effects of surface and subsurface tillage on soybean [Glycine max (L.) Merr.] grain yield, net returns above specified costs, and water use efficiency (WUE) were investigated near Stoneville, MS on a Dubbs silt loam (Fine-silty, mixed, active, thermic lypic Hapludalfs). Conservation tillage with subsoiling maintained or improved soybean grain yield, net returns above specified costs, and WUE up to 68% in three of four years. Conversely, conservation tillage alone either had no effect or decreased soybean grain yield up to 14%, decreased net returns above specified costs up to 20%, and decreased WUE up to 14%. Our data indicate that inclusion of subsoiling minimizes yield and net return declines commonly associated with conservation tillage systems and should be a component of the early soybean production system on medium- to coarse-textured soils.