Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/19/2012
Publication Date: 3/1/2013
Publication URL: http://handle.nal.usda.gov/10113/56867
Citation: Feng, G., Sharratt, B.S., Vaddella, V. 2013. Windblown soil crust formation under light rainfall in a semiarid region. Soil and Tillage Research. 128:91-96. Interpretive Summary: Atmospheric dust originating from agricultural lands impacts air quality in the Pacific Northwest. To protect the health of communities in the region, a regional air quality model has been developed for predicting the occurrence of dust storms. The model, however, requires spatial information on soil crusting because the extent and thickness of soil crusting greatly affects the emission of dust from agricultural lands. We developed an empirical equation to predict soil crust formation and thickness based upon amount of rainfall. This equation can be used by atmospheric and soil scientists in developing more reliable models that simulate wind erosion and atmospheric transport of dust.
Technical Abstract: Many soils in arid and semi-arid regions of the world are affected by crusting, the process of forming a compact layer or thin mantle of consolidated material at the soil surface. Our objective was to evaluate the effect of rainfall quantity on crust formation of five soil types prominent in the Columbia Plateau region of the US Pacific Northwest. The five soils were Athena silt loam, Palouse silt loam, Ritzville silt loam, Walla Walla silt loam, and Warden sandy loam. Soil crusts were formed in the laboratory by simulated rainfall at a rate of 2.5 mm/hr. Total rainfall applied to the soils was 0, 0.15, 0.30, 0.60 and 1.0 mm. Crust strength was measured by a penetrometer while crust thickness was measured by a ruler. Silt and clay content of the five soils ranged from 23 to 64% and from 9-17%, respectively. An increase in crust thickness and strength was observed with an increase in rainfall for all soils. Crust thickness was the same for all soils under each rainfall treatment. Rainfall did not show consistent effects on crust strength of the five soils. Under 0.15 and 0.3mm rainfall, crust strength of the five soils decreased in order: Walla Walla - Athena and Palouse - Ritzville and Warden. These results are consistent with the order of their clay and silt contents. The hardest crusts were formed on Palouse soil under the highest rainfalls. Least squares regression produced a logarithm relationship between crust thickness and total rainfall for the five soils in a laboratory (r=0.98); Applying this relationship to rainfall events in the field proved challenging as the relationship over-predicted crust thickness during low rainfall events. Thus, other factors than rainfall amount appear to be involved in crust formation.