EVALUATION OF COMPACTED UREA FERTILIZERS PREPARED WITH ACID AND NONACID PRODUCING CHEMICAL ADDITIVES IN 3 SOILS VARYING IN PH AND CATION-EXCHANGE CAPACITY-I - NH3 VOLATILIZATION

Efficacy of different acid-producing chemical additives was evaluated in terms of pH, urea hydrolysis, NH4-N dynamics and NH3 volatilization in an Alfisol, a Vertisol and an Inceptisol. Compacting phosphogypsum (PG), diammonium phosphate (DAP), ZnSO4 and KCI separately with urea slowed down urea hydrolysis and reduced NH3 volatilization loss. Peak volatilization loss of NH3 occurred between 2 to 4 days of fertilizer application in Vertisol and Alfisol, but between 3 to 6 days in Incept isol. Cation exchange capacity (CEC) of soil influenced more in reduci ng NH3 loss than native soil pH, as lower amount of NH3 was lost from Vertisol (pH=8.0, CEC=43.92 cmol(c) kg(-1)) than from Alfisol (pH=5.8, CEC=13.82 cmol, kg(-1)). The loss from Inceptisol was in between the above two soils.