Wie kann man Ammoniak aus Gartenerde nachweisen?

If farmland is fertilized with liquid manure, part of the fertilizer can escape into the atmosphere as ammonia. To check this in the experiment, you use a tablespoon full of garden soil. Depending on the type of soil and its content of fertilizers, ammonia can already be detected in the first test due to the alkaline reaction of the indicator strip. In any case, ammonia should be detectable in the second experiment. If this does not work for a change, the soil will not contain bacteria containing urease. In this case, the addition of fresh bean extract or soybean meal could be tried; these two definitely contain urease.