Submitted to: International Conference on Dryland Development
Publication Type: Proceedings
Publication Acceptance Date: 8/28/2006
Publication Date: 1/1/2007
Citation: Wendling, L., Sharratt, B.S., Guanglong, F. 2007. Soil Erodibility and PM10 Emissions Following Tillage in a Dryland Wheat-Fallow Cropping System. International Conference on Dryland Development Interpretive Summary:
Technical Abstract: Traditional agronomic practices in the conventional wheat-fallow rotation employed in central Washington include multiple passes with tillage implements during the fallow 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 fall 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 during a simulated wind event following various postharvest tillage operations. Treatments established in winter wheat stubble included postharvest tillage with either an undercutter implement having overlapping 80-cm wide V-blades or a sweep implement with overlapping 36-cm wide V-blades 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. Aerosol monitors were used to measure PM10 emissions at a height of 5-80 cm above the soil surface. Soil physical properties were measured simultaneously with PM10 emissions and included 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 sweep tillage plots that had the least residue biomass and cover. This study suggests that less intensive tillage in early fall will maximize the retention of residue biomass and reduce PM10 emissions from agricultural soils.