Aggregate size distribution of organic soil eroded by wind

Wind erosion causes losses of organic soil in the province of Quebec's southwestern region, threatening these soils' sustainability. The aggregate size distribution of wind-eroded organic soil was determined. Wind erosion was measured during four different periods on a 1 ha plot with 32 modified Wilson and Cooke (MWAC) samplers systematically positioned in the field. The samplers captured eroded soil with aluminum cans placed at 0.10, 0.25, 0.50 and 0.85 m above the soil surface. The trapped material was collected and taken to the laboratory, where it was grouped by height and sampling period. The aggregate size distribution of the trapped material was determined by dry sieving for sizes 0.045, 0.08, 0.1, 0.1, 0.25, 0.5 and 0.84 mm. A repeated measures model was performed for the compositional data with aggregate size and bottle height as a fixed effect and measurement period as a random effect. The trapped material becomes finer as the height increases. The percentage of aggregates smaller than 0.1 mm increases with height, as opposed to the percentages of aggregates greater than or equal to 0.25 mm, which decrease with height. At 0.25, 0.5 and 0.85 m height, aggregates of size between 0.08 and 0.25 mm dominated the distribution. For material trapped at 0.1 m height, statistical tests found no evidence of differences between the means of 0.08-, 0.1-, 0.25-, and 0.84-mm aggregate sizes, although the highest percentages were 0.1- and 0.25-mm sizes. Aggregates greater than or equal to 0.84 mm were found even up to 0.85 m in height, suggesting that the wind-erodible fraction of organic soils is not equal to 0.84 mm as in mineral soils. These results demonstrate that wind erosion affects organic soils differently than mineral soils. Further research is needed to describe the effects of wind erosion on soils with high organic matter content.