EVALUATION OF COMPACTED UREA FERTILIZERS PREPARED WITH ACID AND NONACID PRODUCING CHEMICAL ADDITIVES IN 3 SOILS VARYING IN PH AND CATION-EXCHANGE CAPACITY-II - YIELD AND N USE EFFICIENCY BY RICE

With a view to evaluate the effect of different chemical additives on the efficacy of urea, a green house study was conducted with wet seaso n rice (Oryza sativa L.) as test crop. The results showed that compact ion of phosphogypsum (PG), diammonium phosphate (DAP), ZnSO4, NH4Cl or KCI with urea increased the rice yield and N use efficiency as compar ed to that obtained with straight urea. A significant positive correla tion between potential N loss (measured by soluble N in floodwater) an d NH3 volatilization (measured by forced air draft system) was observe d. The results clearly indicate that N use efficiency can be increased through suitable modification of urea by compacting it with acid and non-acid producing fertilizers such as NH4Cl, KCI, ZnSO4 and DAP or in dustrial byproduct like phosphogypsum.