A long-term soil fertility experiment in the rice-wheat system was initiated in 1980181 to evaluate the long-term effect of organic manure and inorganicfe rtilizers on grain yield and soil chemical properties. The experiment employed a randomized complete block design (RCBD) and was located on slightly acidic loam soil at Regional Agricultural Research Station (RARS), Parwanipur . The balanced application ofN-P20s-K20 (100-30-30) kglha in both rice and wheat along with 25 kg ZnSO/ha in rice produced the highest grain and straw yield sfor both crops. The combined effect of NPK verses minus PK, minus P and minus K treatments was more pronounced with the advancement of years in both rice and wheat. However, the effect of phosphorus was more pronounced in wheat than rice. The use of FYM alone was not sufficient to meet the nutrient requirement of either crops. However, the addition of 50 kg Niha enhanced the benefit of compost application. Furthermore, the use of 10 t FYM/ha plus 50 kg Niha in rice and residual FYM with NPK in wheat was superior to both FYM alone and imbalancedfertilizer application. A decreasing yield trend was observed for plots treated with imbalanced f ertilizers. The soil analysis results showed that the use of FYM alone or FYM/choppe d straw combined with inorganic fertilizer increased the organic carbon c.ontent of soil. The long-term use of N alone in theform_of urea decreased soil pH value. However, pH was maintained by long-term application of FYM. Similarly, continuous use of FYM alone or with 50 kg Nlha increased the total nitrogen and available phosphorus of the soil. The highest potassium content of wheat straw was obtained with the application of 10 I chopped strawlha plus 50-0-0 in rice season and 100-30-30 in wheat.

A long-term soil fertility experiment in the rice-wheat system was initiated in 1980181 to evaluate the long-term effect of organic manure and inorganicfe rtilizers on grain yield and soil chemical properties. The experiment employed a randomized complete block design (RCBD) and was located on slightly acidic loam soil at Regional Agricultural Research Station (RARS), Parwanipur . The balanced application ofN-P20s-K20 (100-30-30) kglha in both rice and wheat along with 25 kg ZnSO/ha in rice produced the highest grain and straw yield sfor both crops. The combined effect of NPK verses minus PK, minus P and minus K treatments was more pronounced with the advancement of years in both rice and wheat. However, the effect of phosphorus was more pronounced in wheat than rice. The use of FYM alone was not sufficient to meet the nutrient requirement of either crops. However, the addition of 50 kg Niha enhanced the benefit of compost application. Furthermore, the use of 10 t FYM/ha plus 50 kg Niha in rice and residual FYM with NPK in wheat was superior to both FYM alone and imbalancedfertilizer application. A decreasing yield trend was observed for plots treated with imbalanced f ertilizers. The soil analysis results showed that the use of FYM alone or FYM/choppe d straw combined with inorganic fertilizer increased the organic carbon c.ontent of soil. The long-term use of N alone in theform_of urea decreased soil pH value. However, pH was maintained by long-term application of FYM. Similarly, continuous use of FYM alone or with 50 kg Nlha increased the total nitrogen and available phosphorus of the soil. The highest potassium content of wheat straw was obtained with the application of 10 I chopped strawlha plus 50-0-0 in rice season and 100-30-30 in wheat.