The aim of the present work was to assess the response of microbial functional diversity to organic soil amendment and the relationship between the microbial functional diversity and soil carbon availability. Household solid waste compost, horse and rabbit manure and chicken manure were applied at two doses. The same undisturbed soil type (Vertic Argiudoll) was used as reference. Soil suspensions were applied to Biolog EcoPlate and average color development (AWCD), richness (R) and Shannon-Weaver index (H) were calculated. The amendment incorporation resulted in significant increases (p < 0.05) in AWCD, R and H compared to the unamended plots. The regression functions showed linear relationships when R and H were related to soil organic carbon (R(2) = 0.77 and 0.72, respectively). Principal component analysis allowed the differentiation of treatments from the control and the undisturbed sites. The Biolog EcoPlate assay was sensitive to changes in the short term due to management practices.