EFFECTIVENESS AND ECONOMICS OF DRYLAND CONSERVATION TILLAGE SYSTEMS IN THE SOUTHERN GREAT-PLAINS

Precipitation is limited in the Southern Great Plains, and farmers must minimize production costs and control erosion. The purpose of this research was to determine economic feasibility of dryland no- and reduced-tillage systems compared with sweep plowing on Pullman clay loam soil (fine, mixed, mesic Torrertic Paleustoll) in continuous winter wheat (Triticum aestivum L. emend. Thell) and in a winter wheat-sorghum [Sorghum bicolor (L.) Moench]-fallow rotation with two crops produced in 3 yr. Economic analyses considered 4-yr averages of income and treatment costs. In continuous winter wheat, sweep plowing yielded significantly less (425 kg ha-1) than the best no-tillage treatment in 2 of 4 yr. Because of low variable costs, sweeping was most profitable in the short-term, and when machinery depreciation was considered for the long-term, sweep tillage followed by glyphosate lost the least money. In the fallow period between sorghum and wheat, sweep plowing yielded significantly less than the best no-tillage 2 of 4 yr or an average of 275 kg ha-1. However, because of low variable costs, sweep plowing was the most profitable in the short run, $84 ha-1, but $3 ha-1 less profitable in the long run than sweep plowing followed by glyphosate. In the wheat-sorghum part of the rotation, using paraquat or glyphosate alone resulted in lowest yields because of poor weed control. Sweep plowing yielded less than the best no-tillage 1 of 4 yr, but lower costs made it the most profitable, both short and long term.