Long term field trails are conducted to study the change in soil fertility, crop productivity in different agro climatic zone of India. The present field trail is being conducted at Regional Agril. Research Station (AAU), Titabar, Assam, India, falling in Alfisols, characterized as Endo aqualf, clay loam in nature. This paper discusses rice yields, nutrient response, nutrient uptake, soil fertility status and few soil quality parameters in 2004 on the 15^th year of completion of long-term field experiments in rice-rice sequence. Results showed that nutrient combination of 40 kg N, 20 kg P₂O₅ and 20 kg K₂O with 5 t farm yard manure + ZnSO₄ application in soil produced the highest grain yield in both summer and winter rice (87 q ha^-1),  which was significantly higher than conventionally recommended fertilizer dose (40 kg N; 20 kg P₂O₅, 20 kg K₂O + Soil Zn ha^-1 in each season). Grain yield response of rice to applied N, P, K, S, Zn, and FYM were 1.52, 0.44, 0.32, 0.28, 0.51 and 0.75 t ha^-1 during the 15thy year (2003-2004) as compared to1.58, 0.24, 0.40, 0.30, 0.34, 0.53 t ha^-1 over the years (1990-2004) respectively revealing an improvement in P, Zn and FYM response with passage of time. Average nutrient uptake in rice-rice sequence for N, P and K was 37.13 kg, 23.84 kg and 47.51 kg ha^-1 respectively. In addition to high productivity, the treatments receiving 100% NPK +ZnSO₄ + 5t FYM ha^-1, also maintained good level of soil fertility build up (1.23% organic C,   26.7 kg P₂O₅, 185.20 kg K₂O ha^-1. Integrated nutrient management plots also maintained stable soil fertility level over the years as compared to inorganic fertilized plots in this sequence. Further a few soil quality parameters viz. soil physical properties and biological properties were studied. Results indicated that the bulk density in soil varied from 1.29 to 1.38 g cc^-1 in different treatments, water holding capacity ranged between 38.35 to 43.08 %  at the end of final harvesting of crop. Soil biological parameters viz. microbial biomass – C showed a variation of 56.75 to 77.85 mg kg^-1 while dehydrogenase activity in soil varied from 27.06 to 195.32 mg TPF g^-1soil 24^-1 hr in some selective treatments. Besides, linear regression equation (q ha^-1) showing trends of grain yield over years were worked out to see the effect of different treatments over long range of fertilizer application and organic source of nutrient use.