Long Term Alternative Crop Rotation Experiment at USDA-ARS, Akron Colroado.

In 1990, a long term alternative crop rotation experiment was established at the USDA-ARS Central Great Plains Research Station at Akron, Colorado. The goal of this long term effort was to ultimately identify crop rotations other than winter wheat-fallow (WF) that were viable rotation options for the dryland farmers in the Central Great Plains Region. Utilizing no-till technology and more intensive cropping, we have shown several alternative rotations as superior to WF. Our objectives here are to evaluate several of these alternative rotations for economic yield, changes in soil quality, and economic returns. The economics returns to land labor and capital of 7 alternative rotation sequences (established in 1991) is compared. We report some of the effects of rotation intensity on changes in soil organic matter, soil aggregate stability. We also evaluate how far we can push the system to eliminate fallow. Grain yields were measured in each rotation over a 17-year period starting 4 years after rotation establishment (1994-2013). The grain yield data was used to develop rules of thumb regarding long term average yields as affected by rotation sequence and then an economic analysis of net returns to land labor and capital was generated for the 7 rotations. Whereas most of the rotations have been managed using no-till we have included a conventional sweep-tillage Wheat-Fallow treatment for comparison. Our analysis indicates the most favorable sequences were no-till wheat-millet (Panicum miliacium L.)-fallow (WMF) wheat-corn (Zea mays L.)-millet-fallow (WCMF) and wheat-millet (WM). The poorest performance was measured with WF conventional till and WCM no-till. With respect to soil quality enhancement the best rotations were the continuously cropped WCM followed by WCMF and WCF and the poorest were the WF rotations.