Undercutter Tillage to Mitigate Erosion and Improve Air Quality in the Columbia Plateau.

Wind erosion of agricultural lands primarily managed in a wheat-fallow rotation within the Columbia Plateau of the Pacific Northwest US contributes to exceedances of the US Environmental Protection Agency national ambient air quality standard for PM10 (particulate matter ≤10µm in aerodynamic diameter) across the region. Alternative management practices are sought that will reduce erosion and PM10 emissions. Soil flux and PM10 concentrations were measured above adjacent field plots that were subject to conventional or undercutter tillage during the summer fallow phase of a wheat-fallow rotation. After wheat harvest in mid-summer, plots were either disked (conventional) or undercut with wide sweeps (undercutter) the following spring and then periodically rodweeded prior to sowing wheat in late summer. During periods of sustained high winds that caused erosion, total surface soil loss ranged from 3 to 40 g m^-2 for conventional tillage and from 1 to 27 g m^-2 for undercutter tillage. The corresponding loss of PM10 ranged from 0.2 to 5.0 g m^-2 for conventional tillage and from 0.1 to 3.3 g m^-2 for undercutter tillage. Undercutter tillage resulted in a 15 to 65% reduction in soil loss and 30 to 70% reduction in PM10 loss as compared with conventional tillage. Our investigation suggests that undercutter tillage is an effective management practice to reduce erosion and PM10 emissions from summer fallow and improve air quality within the Columbia Plateau.