The effects of partial substitution of chemical fertilizers with different organic sources on rice-rapeseed blackgram cropping sequence were evaluated in coastal saline belts of West Bengal during 2005-06 and 2006-07. The growth parameters, yield components and productivity of all the crops in sequence were the maximum when organic manure was applied along with inorganic fertilizer at 75% of the recommended dose. The effect of well decomposed fishmeal on rice and its residual effect on succeeding crops of rapeseed and blackgram were as good as farm yard manure. The highest rice equivalent yield (9.62 t ha^-1), net returns (Rs. 43728 ha^-1) and net production value (1.86) were recorded when 75% recommended dose of NPK + 2 t well decomposed fishmeal ha^-1 was applied to rice.