Soil properties governing soil erosion affected by cropping systems in the U.S. Pacific Northwest

In the low-precipitation zone (<300 mm annual precipitation) of the inland US Pacific Northwest, no-tillage spring cereal rotations are being examined as alternatives to the traditional winter wheat–summer fallow rotation to control wind erosion. There is limited information, however, regarding the effects of no-tillage cropping systems on soil physical properties and surface characteristics that govern wind erosion in this semiarid region. The objective of this research was to characterize soil aggregates, wetness, strength, roughness, crusting, and crop residue cover and biomass of a silt loam that had been subject to various crop rotations for 11 years in east-central Washington. Crop rotations examined included no-tillage spring barley–spring wheat (NTSB/SW), no-tillage spring wheat–chemical fallow (NTSW/CF), and winter wheat–summer fallow (WW/SF). Soil physical properties were measured in spring 2006 after sowing wheat in the NTSB/SW rotation and in late summer 2006 after sowing winter wheat in the WW/SF and NTSW/CF rotations. In spring, the NTSB/SW and NTSW/CF rotations were characterized by a wetter soil as compared with the WW/SF rotation. In late summer, the NTSB/SW rotation was characterized by a soil surface with more standing stubble and greater crust cover and soil strength as compared with the WW/SF and NTSW/CF rotations. Our results suggest that spring-sown cereal and chemical fallow cropping systems result in wetter soils in spring and retain more surface residue in the late summer that will reduce the risk for wind erosion as compared with the traditional WW/SF rotation in the Pacific Northwest.