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 showed normal after fermentation, but still remains certain ammoniacal odour, inoculation should be delayed and then ted for two or three days until it totally dispersed.