Economic and agronomic assessment of deep tillage in soybean production onMississippi River valley soils

Using deep tillage to alleviate the adverse effects of deleterious soil phy sical properties has been tried many times. Consistent economic returns hav e been reported for in-the-row subsoiling of loamy sand and coarser soils a nd for deep loamy soils where the subsoil slit bisects the water flow chann el during rainfall events where there is runoff. Recent reports of yield re sponses on clayey soils and silt loams led to a reassessment of subsoiling of these soils in Arkansas. A randomized complete block design was conducte d at Pour locations with tillage treatments of conventional shallow, deep c hisel, subsoil dry, subsoil wet, subsoil at 45 degrees to planting directio n, and paratill. Plots were harvested for grain. Economic analysis was perf ormed using the Mississippi State Budget Generator (MSBG). The machinery co mplement was commensurate with that found on farms in the region. Net retur ns above total specified costs (NRAT) rather than above direct costs were c alculated to reflect the decision framework of a producer. A profitable yie ld response was obtained from subsoiling in dry soil on deep alluvial claye y and silt loam soils but not on the thin loessial silt loams. Net returns to subsoiling wet were not significantly higher than those to conventional shallow tillage. Tillage with a chisel plow as deep as it could be operated (approximately 15 cm) was not a substitute for subsoiling because yield re sponses from deeper tillage were not comparable. The 45 degrees subsoiling in dry soil tended to be superior to all other tillage treatments.