WIND ERODIBILITY OF BIOSOLIDS AMENDED SOILS: A STATUS REPORT

1. WIND ERODIBILITY OF BIOSOLIDS AMENDED SOILS: A STATUS REPORT John Tatarko USDA-ARS Wind Erosion Research Unit Manhattan, Kansas & Nikki Stefonick Metro Wastewater Reclamation District Denver, Colorado

2. A consortium of 57 local governments in the Denver metro area. • Treat more than 165 million gallons of wastewater a day. • ~ 52,000 acres of agricultural land 65 miles east of Denver, Colorado.

3. 1 to 3 dry tons/acre depending on background nutrients, crop, and yield goal

7. Objectives: • Determine fraction of biosolids in wind eroded material compared to that of the adjacent biosolids amended land. • Determine wind erodibility of cultivated soils as influenced by applied biosolids.

8. Objective 1 • Wind erosion catchers are located on two sites from December through May. • Biosolid applications: • 3 and 5 (2005-2006) • 4 and 5 (2006-2007) • Catcher and adjacent source soils are collected to determine organic matter and available heavy metal content.

10. Figure 1. Layout of field BSNE sediment sampler clusters in relation to source soil sample locations.

11. Figure 2. Sediment flux (kg m-2) by height for measured data and fitted equation for 4 January, 2006 storm at site DC343.

12. Objective 2 • Five sites at Metrogrow Farms established in December, 2005 on wheat-fallow rotations. • Biosolids applications: • 0, 1, 2, 3, and 5 • Wind erodibility measurements • (3 replicates, sampled quarterly): • aggregate stability • soil surface roughness • aggregate size distribution

13. Table 2. Physical and chemical characteristics of wind erodibility study sites.

14. Table 3. Biosolids applications and organic matter at wind erodibility study sites.

17. Figure 3. Oriented roughness (mm) on sample date at each site with varying number of biosolids applications.

18. Figure 4. Random roughness (mm) on sample date at each site with varying number of biosolids applications.

20. Figure 5. Erodible fraction (%<0.84 mm) of aggregates on sample date at each site with varying number of biosolids applications.

21. Figure 6. Geometric mean diameter (mm) of aggregates on sample date at each site with varying number of biosolids applications.

22. Conclusions Disclaimer: This study is ongoing and statistical analysis is not complete. Only general trends can be observed from the data collected thus far.

23. Conclusions • Oriented Roughness • tends to decrease with time (i.e., precipitation) • higher and more recent applications had highest roughness and retained it longer • no applications had the lowest roughness

24. Conclusions • Random Roughness • low roughness compared to oriented • higher and more recent applications had highest and retained it longer • no applications tended to degrade the fastest

25. Conclusions • Aggregate Size Distribution • tend towards smaller size over time • higher and more recent applications had larger aggregates • no applications tended to smaller sized aggregates

26. Summary • erodibility tends to increase with time after planting (i.e., with precipitation) • biosolids effects are temporary • less erodibility for most recent applications • no applications tended to highest erodibility

27. Thank You