Wind Erosion of Organic Soils: A Field Wind Tunnel Study.

Histosols (also known as organic soils, mucks, or peats) are soils that are dominated by organic matter (>20% ) in half or more of the upper 80 cm.  Forty-four states have a total of 21 million ha of Histosols in the United States. These soils, when intensively cropped, are subject to wind erosion resulting in loss in crop productivity and degradation of soil, air, and water quality. Estimating wind erosion on Histosols has been determined by USDA-Natural Resources Conservation Service as a critical need for the Wind Erosion Prediction System (WEPS) model. WEPS has been developed to simulate wind erosion on agricultural land in the US, including soils with organic soil material surfaces. However, additional field measurements are needed to calibrate and validate estimates of wind erosion of organic soils using WEPS. A field portable wind tunnel was used to generate suspended sediment and dust from agricultural surfaces for soils with 80% (H), 49% (M), and 36% (L) organic matter contents. The soils were tilled and rolled to provide a consolidated, friable surface. Dust emissions and saltation were measured using an isokinetic vertical slot sampler aspirated by a regulated suction source. Suspended dust was collected on filters of the dust slot sampler and sampled at a frequency of once every six seconds in the suction duct using a Grimm optical particle concentration and size analyzer. We also collected samples using a passive Wilson and Cooke sampling cluster as a backup data source. In addition, bulk samples of airborne dust were collected using a sampler specifically designed to collect larger dust samples. The larger dust samples were analyzed for physical, chemical, and microbiological properties. There were no differences between the H and L soils in terms of their steady state dust emission rate under an added abrader flux, but the M soil had less dust emissions by one-third. Analysis of microbiological indicators reveals that the sediment removed by suspension was enriched in β-glucosidase enzyme activity by a ratio of 2.4 and 1.4 for L and H, respectively, compared to the parent soil.