How to make ammonia from urea?
Short answer: use crushed watermelon seeds (urease)
Combine urea in solution with urease, get some ammonia with carbamate intermediary, which rapidly decomposes to ammonia and carbon dioxide.
$$\ce{(NH2)2CO + H2O -&gt;[urease] NH3 + H2NCOOH -&gt; 2NH3(gas) + CO2(gas)}$$
Of course the ammonia gas dissolves in the water and increases the pH.
Sources:

https://www.hemmaodlat.se/research/citrullus%20lanatus%20seeds%20as%20a%20urine%20catalyst%20for%20anthroponic%20use.pdf
https://en.wikipedia.org/wiki/Urease
https://en.wikipedia.org/wiki/Ammonia_volatilization_from_urea