|Schillinger, William - WASHINGTON STATE UNIV|
|Young, Douglas - WASHINGTON STATE UNIV|
Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 15, 2006
Publication Date: February 15, 2007
Repository URL: http://hdl.handle.net/10113/10818
Citation: Schillinger, W.F., Kennedy, A.C., Young, D.L. Eight Years of annual No-Till Cropping in Washington's Winter Wheat - Summer Fallow Region. Agriculture, Ecosystems and Environment. 120: 345-358. 2007. Interpretive Summary: Blowing dust from excessively tilled soil is a major environmental concern in the winter wheat – summer fallow region of the Inland Pacific Northwest, USA. Conservation-till and no-till farming methods have become increasingly popular with farmers in many areas of the world, but adoption of such practices in the low-precipitation dryland zone in the Pacific Northwest has been slow. We evaluated the agronomic and economic feasibility of long-term no-till annual crop production in a typical winter wheat – summer fallow production region. All crops were susceptible to the disease, rhizoctonia, but the disease was reduced, and grain yield increased, when wheat was grown in rotation with barley. Weed seed remained dormant for 6 years and longer. Soil organic carbon increased with no-till during the 8 years to approach that found in undisturbed native soil. Annual no-till crop rotations experienced lower average profitability and greater income variability compared to winter wheat – summer fallow. We found that continuous annual cropping using no-till provided protection against wind erosion and increased soil quality, but the practice involves high economic risk compared to winter wheat – summer fallow in this dry region.
Technical Abstract: Blowing dust from excessively tilled soil is a major environmental concern in the 1.5 million ha winter wheat (Triticum aestivum L.) – summer fallow (WW-SF) region of the Inland Pacific Northwest, USA, where only one crop is produced every other year. An 8-year experiment was conducted to evaluate continuous annual (i.e., no summer fallow) cropping systems using no-till as an alternative to tillage-intensive WW-SF. Soft white and hard white classes of winter and spring wheat, spring barley (Hordeum vulgare L.), yellow mustard (Brassica hirta Moench), and safflower (Carthamus tinctorius L.) were grown in various rotation combinations. Average annual precipitation is 301 mm at the site near Ritzville, WA. Precipitation was less than average in 7 out of 8 years. Rhizoctonia bare patch caused by Rhizoctonia solani AG-8 appeared in year 3 and continued through year 8 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. Remnant downy brome (Bromus tectorum L.) weed seed remained dormant for 6 years and longer to heavily infest recrop winter wheat. There were few quantifiable changes in soil quality due to crop rotation, but soil organic carbon (SOC) increased with no-till during the 8 years to approach that found in undisturbed native soil. Annual no-till crop rotations experienced lower average profitability and greater income variability compared to WW-SF. Annual cropping was generally economically viable when grain yield was 65% of that for WW-SF, which occurred in higher precipitation years. Yellow mustard and safflower were not economically viable. Continuous annual cropping using no-till provides excellent protection against wind erosion and shows potential to increase soil quality, but the practice involves high economic risk compared to WW-SF in this dry region.