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ARS Home » Pacific West Area » Pendleton, Oregon » Columbia Plateau Conservation Research Center » Research » Publications at this Location » Publication #114568
Title: EFFECT OF TILLAGE AND FALLOW ON SOIL ORGANIC CARBON IN THE COLUMBIA PLATEAU

Author
item Wilkins, Dale
item Albrecht, Stephan
item Siemens, Mark

Submitted to: Soil Tillage Research Organization International Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/2/2000
Publication Date: 7/2/2000
Citation: WILKINS, D.E., ALBRECHT, S.L., SIEMENS, M.C. EFFECT OF TILLAGE AND FALLOW ON SOIL ORGANIC CARBON IN THE COLUMBIA PLATEAU. SOIL TILLAGE RESEARCH ORGANIZATION INTERNATIONAL CONFERENCE PROCEEDINGS. JULY 2-7. FT. WORTH, TX. (CD ROM - WILKINS#208-P16.PDF 9 PAGES). 2000.

Interpretive Summary: Winter wheat rotated with fallow in the Oregon, and Washington Columbia Plateau Region is not a biologically sustainable system. This system has degraded the soil resource base through loss of soil organic carbon (SOC). Both tillage and fallow contribute to loss of SOC in these systems. A series of long-term field experiments, some as long as 68 years, at the Research Center near Pendleton, Oregon provided a resource to evaluate the impact of farming management systems on change in SOC. The soil at the site of these experiments well drained silt loam from 1 to 1.5 m deep. SOC continued to decline in conventional winter wheat/fallow with intensive tillage system. Eliminating tillage or fallow reduced the rate of SOC loss. Systems based on no-till without a fallow year in the rotation offer the greatest potential for biological sustainability in the region because they maintain or improve soil organic carbon.

Technical Abstract: Winter wheat (Triticum aestivum L.) rotated with fallow in the Oregon, and Washington Columbia Plateau Region in U.S. is not a biologically sustainable system. This system has degraded the soil resource base through oxidation of soil organic carbon (SOC). Both tillage and fallow contribute to oxidation of SOC in these systems. Traditional tillage in the wheat/fallow system has been sweep, chisel or moldboard plowing followed by secondary field cultivation and rod weeding as necessary to control weeds and maintain a fine-dry surface soil mulch. A series of long-term field experiments including a moldboard plow/fallow, no- till/fallow, moldboard plow ¿ annual wheat and no-till annual wheat have been maintained, some as long as 68 years, at the Research Center near Pendleton, OR. The site of these experiments is 450 m above sea level and the soil is coarse silty mixed mesic Typic Haploxerolls (Walla Walla silt loam). The soil is well-drained loess 1-1.5 m deep over basalt. Topography is nearly level, with slopes ranging from 0 to 4 %. The mean annual precipitation at the Research Center is 415 mm. Soil samples from these experiments were analyzed to determine the effect of tillage and fallow on SOC. Sustainability of SOC content in these systems was determined by using regression analysis to predict SOC content as a function of time, crop residue returned to the field, tillage and fallow. SOC continued to decline in conventional winter wheat/fallow with intensive tillage system. Eliminating tillage or fallow reduced the rate of SOC loss. Systems based on no-till without a fallow year in the rotation offer the greatest potential for biological sustainability in the region because they maintain or improve soil organic carbon and overall soil quality.