Abstract: A field experiment was conducted to study the effects of Sewage Sludge (SS), Municipal Waste Compost (MWC) and Vermicompost (VC) with and without chemical fertilizer (Urea, 50 kg ha-1 + Potassium sulfate, 100 kg ha-1 + Triple super phosphate, 127.5 kg ha-1) on Soil Microbial Respiration (SMR) and Total Organic Carbon (TOC) in a soil cropped to soybean. Experiment was arranged in a complete block design with three replications. Organic amendments were added to soil at rate of 0 (control treatment), 20 and 40 Mg ha-1. Furthermore each level of organic fertilizers with ½ normal of chemical fertilizer was also enriched. Soil samples were taken after one year of fertilization. Results illustrated that application of organic amendments increased TOC and SMR and soybean yield compared to control and chemical fertilizer treatments. Sewage sludge amended soils showed higher SMR, TOC and soybean yield than that of other organic amendment treatments. An increasing trend was observed in all studied parameters, as rates of application increased. All parameters were greater in treatments receiving a combination of chemical fertilizers and organic amendments (enriched treatments) compared to soils receiving organic amendments alone. Results obtained by discriminate analysis indicated that rates of application were more effective to create discriminating among treatments. This study showed that TOC was significantly correlated with SMR. Significant correlation was also observed between SMR and soybean yield.