Submitted to: Aeolian Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/30/2010
Publication Date: 11/1/2010
Citation: Sharratt, B.S., Wendling, L., Feng, G. 2010. Windblown dust affected by tillage intensity during summer fallow. Aeolian Research. 2(2-3):129-134. Interpretive Summary: In the wheat-fallow region of the Pacific Northwest where wheat is grown every other year, wheat growers cultivate the soil multiple times (typically seven times) during the fallow phase of the rotation to conserve soil water for the next wheat crop. This intensive tillage practice, however, exposes the soil to high winds and results in emission of PM10 (particulate matter less than or equal to 10 microns in diameter regulated by the US EPA as an air pollutant) that contributes to poor air quality in the region. Less intensive tillage practices are sought that will reduce PM10 emissions from soil during high winds. Windblown sediment and PM10 were suppressed from soil as a result of reducing the number of tillage operations during the fallow phase of the rotation. Although no tillage (soil not cultivated) resulted in the lowest emission of sediment and PM10 during high winds, this is not yet an economically viable management option for growers. A viable option for wheat growers to reduce the emission of windblown sediment and PM10 from soils in the region is to use reduced or delayed-minimum tillage.
Technical Abstract: Winter wheat – summer fallow is the conventional crop rotation used on more than 1.5 million ha of agricultural land in the low precipitation zone of the Columbia Plateau in the Pacific Northwest United States. This land is very susceptible to wind erosion during summer fallow because multiple tillage operations during fallow degrade and expose the soil to high winds. Because wind erosion contributes to poor air quality as a result of elevated PM10 (particulate matter less than or equal to 10µm in diameter) concentration in the region, we examined possible alternatives to conventional tillage for reducing the emission of windblown PM10 during summer fallow. Soil was subject to seven (conventional), five (reduced), three (delayed-minimum), and zero (no) tillage operations between harvest in July 2004 and sowing in August 2005. Sediment catch and PM10 concentration and wind speed profiles were measured after each tillage operation and sowing under simulated high winds (using a portable wind tunnel) to estimate horizontal sediment and PM10 flux. Horizontal sediment and PM10 flux generally decreased with a decrease in number or intensity of tillage operations. No tillage resulted in the lowest sediment and PM10 flux after most tillage operations; no tillage, however, is not yet an economically viable management option for the region. Sediment and PM10 flux were typically lower for reduced and delayed-minimum tillage than for conventional tillage. Our study suggests that PM10 flux can be reduced from agricultural soils during the summer fallow phase of a wheat–fallow rotation by using reduced or delayed-minimum tillage practices. The reduction in PM10 flux from soils will improve air quality during high winds in the region.