Ammonia is produced from excessive proteolysis, and deamination of amino acids. It's when too much protease can eat at the proteins. Instead of slowly breaking them up into progressively smaller chains, the enzyme breaks them down and strips out an amine, which is basically ammonia.
Causes? Too much geo (either too much activity before candidum took over, or greater than 1:4 geo to candidum), too much humidity (above 92), too high of a temp (above 55), or surface not dried out after the make.
Geo gone wild will cause ammonia. But so can other bacteria and molds. Candidum has similar proteases.