Effect of Long-Term Application of Biosolids On Biological Soil Quality: C Mineralization, and Particulate and Non-Particulate Soil Organic C.

Assessment of C mineralization and fractions in biosolids-amended soil can increase our knowledge on the impact of biosolids application on soil nutrient availability and C sequestration. Soil samples were collected in 2006 from 20 strip-mined fields at Fulton County, Illinois, which received biosolids application during 1972-2004. Since the strip-mined soil was depleted in SOC at the start of the biosolids application, it provides an ideal condition to quantify the change in SOC fractions. The C mineralization was determined using laboratory incubation and particulate organic C (POC) using wet sieving. Application of biosolids considerably increased the potential C mineralization, POC, and non-POC, and such effects increased with the increase in biosolids application rate. As the C mineralization and POC are directly related to soil nutrient supply, and the non-POC is the C associated with clay and represents more stabilized and humified C, these results imply that long-term application of biosolids can increase soil capacity to both supply plant nutrients and sequester C.