Give reason : Urea is better nitrogenous fertiliser than ammonium sulphate.

Explanation

Urea on hydrolysis gives `NH_3` and `CO_2`.
`H_2 NCONH_2 + H_2 O rarr CO_2 + 2 NH_3`.
`NH_3` is assimilated by plants whereas `CO_2` goes into the atmosphere, i.e., `NO` residue is left in the soil. On the other hand, ammonium sulphate on hydrolysis gives `NH_3` and `H_2SO_4`
`(NH_4)_2 SO_4 + H_2 O rarr 2 NH_3 + H_2 SO_4`
`NH_3` is assimilated by plants whereas `H_2 SO_4` is retained in the soil making it acidic.