Improving sustainability of cropping systems in the Central Great Plains

Rotations are changing in the semiarid Central Great. Plains because of no-till systems and crop residue management. With improved precipitation storage in soil, producers now grow corn (Zea mays L.), proso millet (Panicum miliaceum L.), or sunflower (Helianthus annuus L.) in sequence with winter wheat (Triticum aestivum L.) and fallow. A long-term cropping systems study was started at Akron, Colorado in 1990 to evaluate rotations comprised of a diversity of crops, with the goal of developing rotations that minimize frequency of fallow. After 10 years, we examined ecological trends associated with soil structure, nutrient cycling, and pest management as affected by rotations. Soil structure and nutrient cycling improved with continuous cropping, whereas, arranging winter and summer annual crops in a cycle-of-four improved pest management. Producers are seeking rotations that not only are economical, but also improve soil quality; they view fallow and tillage as detriments to long-term sustainability. Therefore, we also suggest options for developing rotations with continuous cropping, based on insight gained from the Akron study. Soils in the Central Great Plains were severely damaged during the Dust Bowl era; producers seek to repair this damage with continuous cropping and no-till. But, a concern with continuous cropping is yield variability and financial risk, which producers previously managed with fallow. Crop-diversity and sequencing in conjunction with residue management and no-till may provide advantages that minimize need for fallow in risk management.