|PI, HUAWEI - Washington State University
Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2018
Publication Date: N/A
Interpretive Summary: Soil crusts created by rainfall or snowmelt can influence the erodibility of soils. The USDA-ARS Wind Erosion Prediction System accounts for the influence of crusting on wind erosion, but the relationship was intuitively developed based upon ancillary data from limited soil types. No studies have been undertaken to scientifically define the relationship between soil crust formation and wind erosion. Progressive development of a soil crust resulted in an exponential decrease in soil erodibility, although crusting did not influence erodibility until attaining 30 to 60% cover. Comparison of measurements with simulations suggested the Wind Erosion Prediction System correctly estimated the erodibility of crusted soils. The USDA-NRCS, land managers, and wind erosion scientists can use Wind Erosion Prediction System with confidence in simulating wind erosion from crusted agricultural soils.
Technical Abstract: Soil crusts provide stability and protection against wind erosion from semi-arid and arid lands. Although erosion is initiated when the friction velocity (U*) exceeds the threshold friction velocity (U*t) of soils, there is little information available on the effect of soil crust cover on U*t. The objective of this study was therefore to evaluate the effect of soil crust cover on the U*t of five loessial soils of the Columbia Plateau, USA. Soil samples were collected from fields managed in dryland crop production. The samples were sieved and the erodible fraction was placed in 1x0.2x0.015 m trays. Water drops (4.5-mm diameter) were applied to the soil surface at a known density which, after drying, created various percentages of crust cover. The trays were placed inside a wind tunnel to assess U*t which was determined by systematically increasing wind speed until an increase was observed in TSP (total suspended particulates) concentration inside the tunnel. No significant differences in U*t were found among 0, 15, and 30% cover, but significant differences in U*t were found between 60 and 100% crust cover. The U*t of 100% crust cover was about twice that of 0% cover. Crust crushing energy, which influences abrasion, did not vary across crust cover treatments. The Single-event Wind Erosion Evaluation Program (SWEEP) revealed a similar influence of crust cover on U*t. The SWEEP adequately simulated U*t for 0, 15, and 30% crust cover, but overestimated U*t for 60 and 100% cover. The results of this study suggest that crusts effectively protect the soil from wind erosion by increasing U*t.