Winter wheat (Triticum aestivum L.) is the most common dryland crop grown in the central Great Plains. Producers in this region include fallow in the rotation to minimize yield variability due to erratic precipitation. However, fallow degrades soil quality by increasing erosion potential and loss of organic matter. Fortunately, minimum‐till production systems and residue management improve water use efficiency by plants, thus producers can crop more frequently. We evaluated eight rotations comprised of various sequences of winter wheat (W), corn (Zea mays L.) (C), proso millet (Panicum miliaceum L.) (M), sunflower (Hettanthus annum L.) (S), and fallow (F) in comparison to W‐F at Akron CO. Our goal was to identify rotations that can replace W‐F to minimize the frequency of fallow. The soil was a Weld silt loam (Aridic Paleustoll). Continuously cropping with W‐C‐M and W‐M almost doubled total grain yield compared with the conventional system of W‐ F. Other rotations such as W‐C‐F, W‐C‐S‐F, and W‐C‐M‐F yielded >60% more on an annualized basis than W‐F. Winter wheat yield increased with longer time intervals between wheat crops. Sunflower yielded the most when grown only once every 4 yr; more frequent cropping favored diseases. Sunflower reduced yield of the following crop, especially during dry years. Yield variability was highest with corn and sunflower, whereas proso millet showed the least variability. Producers can manage yield variability by diversifying crops in the rotation, as annualized yield variability of W‐M and W‐C‐M was similar to W‐F. With residue maintenance and minimum tillage, producers can crop more frequently, thus increasing land productivity while minimizing the frequency of fallow in this semiarid region.
Research Question
Since the 1930s, winter wheat‐fallow has been the prevalent crop rotation for the semiarid Central Great Plains. Because available water is usually the most limiting resource, producers rely on fallow to minimize the impact of erratic precipitation on grain production. However, fallow degrades soil quality by increasing erosion and loss of organic matter.
Development of minimum‐till production systems has altered the water relations in our agroecosystems. Minimizing tillage leaves more crop residue on the soil surface, subsequently increasing precipitation storage and water use efficiency of crops. Thus, with minimum‐till systems, more intensive cropping is possible in the central Great Plains.
This study evaluated cropping systems composed of various sequences of winter wheat (W), corn (G), proso millet (M), sunflower (S), and fallow (F), including continuous cropping. Our goal was to identify rotations that may be successful alternatives to W‐F.
Literature Summary
With reduced‐till systems, several crops have been successful in a wheat‐summer crop‐fallow rotation in this region, including proso millet, corn, and grain sorghum. In addition, longer rotations with three crops in 4 yr, such as W‐C‐M‐ F, are also successful and have increased land productivity by 70%. Another p...
