1. In general, the urea content in formula should not exceed 0.7% of substrates, if the content of urea is too high, it will inhibit the growth of spawn or cause the poisoning and death of spawn.
2. Nitrogen Nutrition should be added entirely when building, it is forbidden to add at the moment of turning.
3. If other indexes show normal situation after fermentation, but still remain certain ammoniacal odour, inoculation should be delayed and then people could ted for two or three days until it totally dispersed.