Diversifying and Intensifying Cropping Systems in the Southern Great Plains.

The predominant cropping systems in South Central Kansas historically have been continuous wheat and wheat – grain sorghum – fallow. Intensifying these cropping systems by incorporating additional crops can potentially reduce production and marketing risks, facilitate greater soil and water conservation, and increase production. A series of studies was conducted during the past 20 years to determine the effect of intensifying the traditional cropping systems on winter wheat and alternative crop yields.
    Winter wheat was planted in rotations following several alternative crops in different rotations and tillage systems. Yields were compared to continuous winter wheat under conventional and no-till practices. Treatments were replicated four times in a randomized block design in a split plot treatment structure with crop as main plots and six nitrogen rates as subplots in the continuous wheat study.  In the rotational studies, treatments were replicated five times in a randomized block design with each crop represented each year.
    Initially, the conventionally tilled, continuous wheat yields were greater than those from the other systems. However, over time, wheat yields following soybeans have increased, reflecting the effects of reduced weed and disease pressure and increased soil nitrogen. Wheat yields responded favorably to the presence of a cover crop only in years with adequate cover crop growth. Management of grass weeds in the cover crop was a key factor for increasing wheat yields. Wheat planted immediately after corn or sorghum was lost in years when fall and winter moisture was limited. This did not occur in continuous winter wheat, regardless of tillage, or for wheat after soybeans. Soybean and grain sorghum yields were influenced more by weather than by previous crop. The traditional cropping systems of South Central Kansas can be successfully diversified and intensified with proper attention to crop sequence, soil moisture management, and weed control.