Tuesday, November 6, 2007
163-14

Reduced Tillage and Crop Rotation Systems with Winter Wheat, Grain Sorghum, Corn and Soybean.

Mark Claassen, Agronomy, Kansas State University, 202 S. Roupp, Hesston, KS 67062 and Kraig L. Roozeboom, 2004 Throckmorton Plt. Sci. Ctr., Kansas State University - Agronomy, Kansas State University, Dept. of Agronomy, Manhattan, KS 66506-5501.

Winter wheat is a dominant component of cropping systems in the central Great Plains, but row crop utilization has become more common regionally in crop rotations that conserve moisture by reduced tillage or no-tillage. This study was conducted over a 10-year period on a Ladysmith silty clay loam (Udertic Argiustoll) to evaluate the effects of tillage on corn and soybean production versus grain sorghum in an annual rotation with winter wheat and to compare these rotations with monoculture wheat and grain sorghum. Burn, chisel and no-till systems were maintained for continuous wheat; v-blade and no-till for each row crop (corn, soybean, and grain sorghum) in annual rotation with wheat; and chisel or no-till for continuous grain sorghum in early (May) and conventional (June) dates of planting. Each system, except no-till, included secondary tillage with a sweep-treader. Wheat in all rotations was planted no-till after each row-crop harvest. Tillage in alternate years did not consistently affect yield of no-till wheat after row crops. Wheat after soybean and corn produced greatest average yields of 3965 and 3877 kg ha-1. In rotation with grain sorghum, wheat produced significantly less at 3279 kg ha-1, comparable to continuous wheat. The burn system increased continuous wheat yields in some years, but decreased production in high-rainfall seasons because of poorer drainage. On average, continuous wheat yields maintained 3246 kg ha-1 without significant effect of tillage system. Corn and soybean yields averaged 4447 and 1922 kg ha-1 with no significant tillage effect. Grain sorghum after wheat averaged 5620 kg ha-1, 1035 kg ha-1 more than continuous grain sorghum without tillage effect in either case. Planting date effects on grain sorghum varied in relation to the incidence of drought stress. However, on average, neither planting date nor tillage significantly influenced grain sorghum production.