Submitted to: ASA-CSSA-SSSA Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/10/2005
Publication Date: 11/10/2005
Citation: Wendling, L.A., Sharratt, B.S., Feng, G. 2005. Emissions from Soil as Affected by Tillage in a Dryland Wheat-Fallow Cropping System. . ASA-CSSA-SSSA Proceedings.
Technical Abstract: Agronomic practices in the conventional wheat-fallow region of central Washington State traditionally involve the use of multiple passes with tillage implements during the fallow cycle to create a dust mulch layer, the purpose of which is to retard the loss of soil moisture and to manage weed populations. High winds and low rainfall during the summer and early autumn create conditions optimal for wind erosion of soil. Windblown dust originating from agricultural fields is the primary source of PM10 (particulate material '10µm in diameter) contributing to poor air quality in the region. Less intensive tillage practices are sought that will reduce PM10 emissions and improve air quality while maintaining agricultural productivity. The objective of this study is to quantify PM10 emissions from soil during a simulated wind event following a sequence of various tillage operations. Experimental plots were established in winter wheat stubble on a silt loam soil near Lind, Washington, where the mean annual precipitation is approximately 244 mm. Three distinct sequences of tillage operations were performed after wheat harvest in the autumn and in the spring and summer. The most aggressive tillage sequence, simulating conventional tillage practices in this region, included the use of sweep and chisel implements in the autumn followed by primary tillage with a cultivator in the spring. A less aggressive tillage sequence involved the use of a noninversion undercutter implement in both the autumn and the spring. The least aggressive tillage treatment involved no autumn tillage followed by primary tillage in the spring using the noninversion undercutter implement. Rodweeding was performed throughout the summer in all treatments as necessary for weed control. A portable wind tunnel was used to assess PM10 emissions over a known surface area in field plots following each tillage operation. Differences in PM10 emissions among post-harvest tillage treatments were apparent. These differences in PM10 emissions among tillage treatments became more pronounced following spring and summer tillage operations. These results suggest that wheat growers within the wheat-fallow region of the Columbia Plateau can reduce PM10 emissions from soils and improve air quality in communities downwind by using less intensive tillage in early autumn and spring.