Grain Yields and Soil Water Dynamics in a Long-Term, Large-Scale Dryland Cropping Systems Study.

A large-scale dryland cropping systems research and demonstration project was started in 1993 with 5 rotations: wheat-fallow, wheat-sunflower-fallow, wheat-grain sorghum-fallow, wheat-corn-fallow, and wheat-proso millet-fallow.  The wheat-fallow rotation was performed under three different tillage systems: no-till, conventional till, and reduced till.  Over the years various changes have been made in crop rotation with the addition of more intense rotations utilizing stacked row-crops.  Tillage practices in use have declined to full no-till for all plots except a reduced till wheat-fallow treatment.  Throughout this time crop yields, biomass production, and soil water measurements have been collected.  These data offer the opportunity to evaluate potential dryland cropping systems in a long-term, production scale framework.  Analysis of crop yields as affected by rotation and accompanying soil water dynamics will be the focus of this presentation.