A field experiment was conducted at Agricultural Research farm, BHU, on sandy clay loam soil with rice (var. HUR-105) to find out the influence of biochar, carpet waste, FYM and PGPR on biological properties of alluvial soils of Varanasi. The enzyme dehydrogenase activity ranged from 95.9 to 231.6 μg TPF produced g^-1soil day^-1 whereas the enzyme alkaline phosphatase activity ranged from 49.1 to 108.7 μg PNP produced g^-1 soil hr-1. The activity of both the enzyme was highest at 80 days after transplanting (DAT) of rice in treatment receiving biochar + carpet waste + FYM + PGPR. The microbial population of bacteria, actinomycetes and fungi were ranged 23-48 ×105, 26-12 ×104 and 10.3-20 ×103 cfu g^-1 of soil respectively. The microbial population was highest at 80 DAT of rice than 40 and 120 DAT of rice crop. The maximum microbial population was found in T₁₀ which receive biochar + carpet waste + FYM + PGPR at all the growth events. The biological properties of soil were positively and significantly correlated with organic carbon content of soil.