Soil Property Effects on Wind Erosion of Organic Soils

Abstract

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 (NRCS) 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 ranging from 12% to 67% organic matter. The wind erodible fraction ( 106 microns) varied with organic matter (OM) content and ranged from 2.41 g cm-3 for the soil with the lowest OM content to 1.61 g cm-3 for the soil with highest OM content. The lowest OM soils produced the highest dust concentrations both during initial blow-offs and when abraded. The soil with the lowest non-erodible fraction (26%) had distinctly higher dust emissions compared with the other soils (non-erodible fraction >49%). The dust emissions from the four high OM soils (>25%) were not significantly increased by the introduction of abrader. Microbiological analysis shows enzyme activity (EA) in the sediment lost from plots as saltation and suspension was greater than the bulk soil. For example, s-Glucosidase activity (EA) in the sediment removed by saltation was enriched by a ratio of 2.4 for the soil with the lowest OM content and by 1.4 for highest OM content soil, compared to the parent soil. For the suspended dust load EA analysis, enrichment ratios were 2.4 and 1.5 for the dust and parent soil, respectively. These results demonstrate the following: 1) Variations in dust emissions can be linked to soil properties; 2) Surface soil organic matter content affected wind erodibility and dust emissions; 3) Abrasion did not significantly increase dust emission rates from high OM soils due to their high mechanical stability; 4) The relative enrichment of EA in eroded sediment compared with the parent soil demonstrates soil degradation due to wind erosion with negative implications for soil sustainability.