|Feng, Guanglong - WASHINGTON ST UNIVERSITY|
Submitted to: International Conference on Dryland Development
Publication Type: Proceedings
Publication Acceptance Date: December 1, 2005
Publication Date: March 1, 2006
Citation: Wendling, L., Sharratt, B., Feng, G. 2006. Soil erodibility and PM10 emissions following tillage in a dryland wheat-fallow cropping system proceedings. Abstracts of Oral Presentations, Eighth International Conference on Development of Drylands. Beijing, China p. 40. Technical Abstract: Traditional agronomic practices in the conventional wheat-fallow rotation employed in the Columbia Plateau of central Washington include multiple passes with tillage implements during the fallow portion of the cropping cycle, both to create a dust mulch layer to retard soil moisture losses and to manage weed populations. This dust mulch, in association with high winds and low rainfall during the early autumn season, creates soil surface conditions optimal for wind erosion and emission of PM10 (particulate matter ' 10µm in diameter regulated by the US EPA as an air pollutant). Therefore, less intensive tillage practices are sought that will reduce wind erosion and PM10 emissions from fallow fields. The objective of this study is to quantify PM10 emissions from a silt loam soil in the low rainfall area of the Columbia Plateau during a simulated wind event following various postharvest tillage operations. Experimental plots were established in winter wheat stubble in an area of the Columbia Plateau with 244 mm mean annual precipitation. Treatments included postharvest tillage with either a noninversion undercutter implement having overlapping 80-cm wide V-blades on 75-cm spacings or a sweep implement with overlapping 36-cm wide V-blades on 30-cm spacings, and a control treatment without any postharvest tillage. Tillage was performed at a depth of 13 cm. A portable wind tunnel was used to generate air flow over a known surface area in the experimental field plots. DustTrak aerosol monitors were used to measure PM10 emissions at various heights above the soil surface within the working section of the wind tunnel. Soil physical properties were measured simultaneously with PM10 emissions, including the surface residue biomass and cover, stubble height, aggregate size distribution and stability, surface roughness, and soil water content. PM10 emissions were suppressed by a crust cover in no-till plots whereas emissions were highest from experimental plots that had the least residue biomass and cover. This study suggests that less intensive tillage in early autumn and spring will maximize the retention of residue biomass and reduce PM10 emissions from silt loam soils within the wheat-fallow region of the Columbia Plateau.