GB/T 3595-2000 stipulates that the content of ammonia nitrogen in fertilizers is determined by the Titrimetric method after distillation. This method is suitable for all kinds of fertilizer products. First, the fertilizer sample is heated with a strong alkali to convert the ammonia nitrogen into ammonia distillation, which is absorbed by an excess sulfuric acid solution. Then the remaining sulfuric acid is titrated with a standard alkali solution, and the ammonia nitrogen content is calculated by the amount of alkali consumed. The standard specifies the required instruments, such as distillingapparatus, Burette, etc., and specifies the preparation of reagents. Detailed description of Sample Handling, distillation operation and titration steps. According to this standard, the ammonia nitrogen content of fertilizers can be accurately determined, providing a key basis for mass control of fertilizers and rational fertilization.