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ARS Home » Pacific West Area » Pendleton, Oregon » Columbia Plateau Conservation Research Center » Research » Publications at this Location » Publication #260583

Title: One Tillage Pass Can Produce Highly Effective Tilled Summer Fallow

item Wuest, Stewart
item SCHILLINGER, WILLIAM - Washington State University
item CORP, MARY - Oregon State University

Submitted to: Agricultural Experiment Station Publication
Publication Type: Experiment Station
Publication Acceptance Date: 5/15/2010
Publication Date: 6/15/2010
Citation: Wuest, S.B., Schillinger, W.F., Corp, M.K. 2010. One Tillage Pass Can Produce Highly Effective Tilled Summer Fallow. Dryland Research Report 101, Columbia Basin Agricultural Research Center, Oregon State University - Agricultural Experiment Station, Adams, Oregon. 7pp.

Interpretive Summary:

Technical Abstract: This article presents a collection of findings that support a change in perspective on tilled soil mulch in Pacific Northwest summer fallow systems. Our focus is on millions of acres in the driest portions of the Inland Pacific Northwest where tilled fallow is generally considered necessary for profitable winter wheat production. Tillage-based fallow generally retains adequate seed-zone moisture for early (late August – early September) establishment of winter wheat, whereas sufficient seed-zone moisture is generally not present in no-till fallow by late summer. It is still commonly believed that a relatively fine soil (“dust”) mulch is needed to provide a barrier to stop moisture loss during the summer months prior to seeding. A growing body of research has demonstrated that this is not true. In a series of experiments, the presence of more and larger soil clods both on the soil surface and within the tilled soil mulch did not reduce the insulating effect. We found that an undercutter without any rodweeding actually performed better than when rodweeded immediately after undercutting, or rodweeded later in the season, or rodweeded several times. No-till allows the best penetration of rain, and we recommend no-till over tilled fallow wherever timely rains allow good winter wheat establishment. Despite questions regarding mid-summer weed control and a design for more suitable seed drills, the prospects of a very low disturbance, erosion resistant summer fallow system with excellent seed-zone moisture and water conservation make further efforts in the driest winter wheat regions imperative. A more accurate understanding of the physics of tilled mulches promises to improve both profitability and sustainability.