Ten Years of Continuous Annual No-Till Cropping vs. Winter Wheat – Fallow in the Pacific Northwest.
William F. Schillinger1, Douglas L. Young1, Ann Kennedy2, and Timothy C. Paulitz2. (1) Washington State Univ, Crop and Soil Sciences Dept, Lind, WA 99341, (2) USDA-ARS, WSU USDA-ARS, 217 Johnson HallPO Box 646421, Pullman, WA 99164-6421
A 10-yr experiment was conducted to evaluate continuous 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 8 out of 10 years. Annual no-till crop rotations generally experienced lower average profitability and greater income variability compared to WW-SF. Spring wheat was economically viable when grain yield was 65% of that for WW-SF, which usually occurred in higher precipitation years. Yellow mustard and safflower were not economically viable and provided no noticeable rotation benefit for subsequent cereal crops. Rhizoctonia bare patch caused by Rhizoctonia solani AG-8 appeared in year 3 and continued unabated through year 10 in all no-till plots. All crops were susceptible to Rhizoctonia, but bare patch area in wheat was reduced, and grain yield increased, when wheat was grown in rotation with barley every other year. There were few quantifiable changes in soil quality due to crop rotation, but soil organic matter increased with no-till during the 10 yr to approach that found in native, undisturbed soil. A model is being developed to help farmers decide when it may be desirable to plant spring cereals (in lieu of summer fallow) based on water stored in the soil during the winter and long-term April, May, and June precipitation.