Fourteen Years of Diverse Annual No-till Cropping in Washington's Winter Wheat - Summer Fallow Region.

Fourteen Years of Diverse Annual No-Till Cropping in Washington's Winter Wheat – Summer Fallow Region

William F. Schillinger, Ann C. Kennedy, and Timothy C. Paulitz

Washington State University and USDA-ARS

We have competed the 14^th year of a cropping systems experiment to evaluate diverse annual (i.e., no summer fallow) cropping systems using no-till as an alternative to tillage-intensive winter wheat (Triticum aestivum L.) – summer fallow (WW-SF). Soft white and hard white classes of winter and spring wheat, spring barley (Hordeum vulagare L.), yellow mustard (Brassica hirta Moench), and safflower (Carthamus tinctorius L.) were grown in various rotation combinations. Average annual precipitation is 300 mm at the site near Ritzville, WA.  Precipitation was less than average in 11 out of 14 years.  Although annual no-till crop rotations have greater variability and less stability compared to WW-SF, many useful lessons have been learned. A model was developed to help farmers decide when it may be desirable to plant spring cereals (in lieu of summer fallow) based on measured over-winter soil water storage and expected spring rainfall.  There was a gradual increase in soil organic carbon (SOC) in the surface 0-5 cm with no-till that approached that of native soil by year 8, and these high SOC levels have been sustained with no-till annual cropping through year 14. Rhizoctonia bare patch caused by Rhizoctonia solani AG-8 appeared in year 3 in all no-till plots, reached peak levels by year 8, but declined to near zero by year 13. This is the first documentation of natural suppression of Rhizoctonia bare patch in long-term no-till cropping systems in the United States. This field experiment is an extremely valuable living laboratory that will be continued for the foreseeable future.