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Title: Stability of soil organic matter under long-term biosolids application

Author
item TIAN, G - Water Reclamation District
item Franzluebbers, Alan
item GRANATO, T - Water Reclamation District
item COX, A - Water Reclamation District
item O'CONNOR, C - Water Reclamation District

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2012
Publication Date: 2/5/2013
Citation: Tian, G., Franzluebbers, A.J., Granato, T.C., Cox, A.E., O'Connor, C.O. 2013. Stability of soil organic matter under long-term biosolids application. Applied Soil Ecology. 64:223-227.

Interpretive Summary: Cleaning up used city water results in a large amount of solid material that is collected and in need of disposal. Municipal biosolids from waste-water treatment plants are often applied to land as a means of disposal. However, since the materials are relatively high in carbon and nutrients, and these materials are often repeatedly applied to the same land area, a big question has remained unknown as to how these materials might affect the biological quality of soils. A group of scientists from the Metropolitan Water Reclamation District of Greater Chicago and USDA Agricultural Research Service in Watkinsville Georgia evaluated the impact of duration (up to 33 years) and rate of municipal biosolids application on soil carbon sequestration and biological soil quality in a field study in Fulton County, Illinois. As expected, soil organic carbon sequestration was highly related to the quantity of biosolids applied. More interestingly though, biological soil quality (i.e. soil microbial biomass and its activity) was also greatly increased with increasing application rate of biosolids. These results demonstrate the strong link that occurs between soil organic carbon sequestration and the improvement in biological soil quality. The results also demonstrate the enormous potential of improving soil quality (and sequestering carbon in soil) with the long-term application of human-derived waste, which effectively recycles carbon and nutrients in a more ecologically compatible manner than simply land disposal or dumping. The results of this study can be used by municipalities and neighboring agricultural landowners as evidence that biosolids application on degraded farmland can recreate an ecologically robust soil system, capable of supporting a thriving soil microbial population. Biosolids application will improve the productive potential of degraded soils.

Technical Abstract: The long-term impact of biosolids application on soil C sequestration and nutrient availability through soil biological activity measurements remains unknown. We determined a diversity of stable and biologically active soil C and N fractions from strip-mined (Entisol) and un-mined fields (Alfisol and Mollisol) in Fulton County, Illinois. Soil was collected in 2006 at two depths (0-15 and 15-30 cm) from 45 fields that had received different quantities of liquid and dry municipal biosolids application from 1972 to 2004. Without biosolids application, particulate organic C (POC) of soil ranged from 3.0 to 6.9 g kg-1at 0-15 cm depth and 0.9 to 3.7 at 15-30 cm depth. With application of biosolids (200 to 500 Mg ha-1 dry weight), POC was 13.5 to 53.3 g kg-1at 0-15 cm depth and 7.9 to 35.5 g kg-1 at 15-30 cm depth. Application of biosolids increased the mineral-associated organic C to 15 to 43.1 g kg-1 (0-15 cm) and 11 to 30.9 g kg-1 (15-30 cm) from a baseline of 2.8 to 20.5 g kg-1 without biosolids. Similarly positive effects of biosolids application were observed for particulate organic N, mineral-associated organic N, and potential C and N mineralization. Biological soil quality and soil organic C sequestration were increased with the long-term application of municipal biosolids.