The HSN code for urea is 3102. This heading covers mineral or chemical fertilizers, containing nitrogen.
Here is a description:
31: Fertilizers
02: Mineral or chemical fertilizers, containing nitrogen
Specifically, urea is classified under:
3102.10: Urea, whether or not in aqueous solution
For GST purposes in India, the GST rate for goods classified under HSN code 3102.10 (urea) is generally 5%.