Rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth., HV) green manures are popularly used in agricultural soils to supply nitrogen (N) and enhance soil microbial activity and diversity. Here, effects of rye, HV, and their mix (rye+HV) on inorganic-N and its relationship with microbes were tested through a pot experiment. Soils were sampled at days 25 and 38 after fresh green manures were incorporated. Inorganic-N (NH₄⁺-N, NO₃^–-N) and β-glucosidase enzyme (BG) was colorimetrically measured. Soil microbial biomass (SMB) was determined through chloroform fumigation methods. Soil DNA was extracted and targeted to the ammonia-oxidizing bacteria (AOB) and 16S to quantify the nitrifier and show bacterial diversity, respectively. In result, NH₄⁺-N concentration under HV was 52% improved compared with control at days 25, wherein SMB tended to positively correlate (P=0.059). Quantity of AOB was not altered, however, relative abundance of Bacteroidetes in HV and rye+HV was 1.5 times increased, suggesting the contribution on N mineralization. At days 38, inorganic-N concentration was not changed, but positively correlated to BG (P=0.003). It may be caused by carbon utilization by Gammaproteobacteria in rye. In conclusion, SMB, BG, and specific bacterial phylum can correlatedly become indicators of N supply, particularly in early timing.