Escalation of wind erosion from oilseed crops grown in the USA Pacific Northwest

摘要

The United States has a goal to produce 136 billion liters of biofuel by 2022 with 79 billion liters being derived from advanced biofuels.The Pacific Northwest is expected to produce about 5％of these advanced biofuels.Although progress is being made in growing oilseeds for advanced biofuels,little is known concerning the impact of growing oilseed crops on natural resources.The objective of this study was to examine the impact of growing oilseeds in conventional wheat-fallow rotations on wind erosion and PM10(particles ≤10μm in diameter)emissions in Washington state where atmospheric PM10 is an acute environmental concern.Wind erosion and PM10 emissions were measured after sowing winter wheat into summer fallow of a winter wheat-summer fallow(WW-SF)rotation and a winter wheat-camelina-summer fallow(WW-C-SF)rotation or winter wheat-safflower-summer fallow(WW-S-SF)rotation.During the 13-month fallow phase of the rotation,the soil was cultivated once in spring and rodweeded prior to sowing winter wheat.A wind tunnel was used to assess horizontal sediment and PM10 flux after sowing wheat(period of the rotation most susceptible to erosion).Sediment and PM10 flux were as much as a 250％higher after sowing winter wheat in the WW-C-SF and WW-S-SF rotations compared with the WWSF rotation.Less surface biomass following the oilseed crop likely contributed to the higher sediment and PM10 flux from the WW-C-SF and WW-S-SF rotations.Our results suggest that wind erosion and PM10 emissions are accentuated after sowing winter wheat in WW-C-SF and WW-S-SF rotations as compared with the traditional WW-SF rotation.Further research is required to assess life cycle analysis of emissions during the fallow phase of the rotations because less frequent use of summer fallow in the WW-C-SF and WW-S-SF rotations may compensate for higher emissions after sowing wheat in these rotations than the WW-SF rotation.