urea to ammonia

SMD1990

(NH₂)₂CO + H₂O = CO₂ + 2 NH₃

According to Wikipedia, human feces contain several bacteria which possess the enzyme urease, which is supposed to catalyze the above reaction.

A couple of days ago, I filled a 60 mL bottle with urine and a little bit of poop, then covered it with a small balloon, hoping to collect the resulting gases.

Well, thus far, I have observed no apparent change. How long should it take?

Also, could it be that the ammonia and carbon dioxide are dissolving into the water?