Abstract

                                A laboratory experiment was conducted to monitor the changes in different forms of inorganic and organic N and P in an alluvial and an acidic soil fertilized with inorganic N and P either alone or in combination. Results revealed that in both the soils exchangeable NH4+ and soluble NO3- decreased with increase in the period of investigation. Irrespective of soils, addition of inorganic N alone causes faster rate of N loss from the soil than combined application of N and P fertilizers. Combined application of N and P fertilizers accentuates mineralization process of hydrolysable NH4+ and amino acid-N fractions particularly, in acidic Jhargram soil. Irrespective of soils, the highest amount of decrease in active P (saloid-P + Al-P + Fe-P + Ca-P) was recorded in the treatment fertilized with inorganic P alone. Higher amount of decrease in organic P was recorded in alluvial Mohanpur soil than that of acidic Jhargram soil treated with inorganic P alone.

Key words : Acid soil, Organic N, Organic P, Active P