Study of nitrogen release pattern in Vertisol as influenced by green manure and farmyard manure application in rice. A field experiment was conducted during kharif season of the year, 2013. The Research Farm, IGKV, Raipur is situated in mid-eastern part of Chhattisgarh. The experiment consisted of six treatments and was laid out in a randomized block design with four replications. The treatment details are (T1) - control, (T2) -50% Recommended dose of fertilizer (RDF), (T3) -100% RDF, (T4) -150% RDF, (T5) -100% RDF +FYM, (T6) -50% RDF + green manure (GM). The optimal amounts of N, P2O5 and K2O (100%RDF) are 100:60:40 kg ha-1 for rice respectively. The soil samples (0 to 15 cm depth) were collected at an initially 4 days interval and after panicle initiation it was taken at 7 days interval. The results indicated a significant increase in the rate of N mineralization in the 16–68 days after transplanting (DAT), whereas in initial stage it was not significantly from 0-12 DAT. The highest rate of ammonical N was observed in treatment 50% RDF +GM (50.96 kg ha-1) at 52 DAT and thereafter it slowed down, followed by 100% RDF + FYM treated plot (47.06 kg ha-1) at 48th DAT. Among the different treatment it was recorded that NO3--N status increases upto 56 DAT and thereafter it decreases. In case of available N was recorded highest in the treatment T6 i e. 50% RDF+GM treated plot at 52 DAT (208.05 kg ha-1), while it was recorded lowest in control plot at 0 DAT (133.59 kg ha-1).