WIND ERODIBILITY OF BIOSOLIDS AMENDED SOILS: A STATUS REPORT

The Metro Wastewater Reclamation District has been applying municipal biosolids to agricultural land known as the METROGRO Farm since 1993. The METROGRO Farm is located approximately 65 miles east of Denver, Colorado near Deer Trail, Colorado. The agricultural land in this area has historically been susceptible to wind erosion. Since biosolids can potentially influence soil wind erodibility and become suspended, the objectives of this study are to: 1) determine the wind erodibility of cultivated soils as influenced by applied biosolids and 2) determine the fraction of municipal biosolids contained in the material eroded by wind from biosolids amended cultivated lands. Five sampling sites on or adjacent to the METROGRO Farm were selected in December, 2005 on wheat-fallow rotations which have had 0, 1, 2, 3, and 5 biosolids applications. Soil wind erodibility measurements were taken in 3 replicates at each site, including aggregate size distribution, aggregate stability, and soil surface roughness and will be re-sampled every three months to capture seasonal differences in wind erodibility throughout the entire two year rotation. In addition, passive wind erosion sediment (dust) samplers are located on two sites from December through May, which have had three or more applications of biosolids. The adjacent wind erosion source soils in the field as well as the sediment samples (collected after each wind erosion event) are analyzed to determine organic matter and available heavy metal content. The analysis of sediment and source samples will be compared to determine the biosolids enrichment of soils eroding from amended lands. Results will indicate the effect of biosolids on potential soil erosion by wind as well as the fraction of biosolids that can erode from amended surfaces.