Fecha de publicación: 16/07/2021 Fuente: Wipo Tobacco Agriculture The invention discloses a preparation method and a detection method of a fertilizer liquid synergist, belonging to the technical field of agricultural fertilizers. The method comprises the following steps: 1, adding potassium fulvate into tobacco waste liquid, conducting stirring for 10-30 minutes at 20-40 DEG C, then adding polyglutamic acid, and conducting stirring for 10-30 minutes at 20-40 DEG C to obtain a liquid mixture A; and 2, uniformly mixing glutamic acid, chitosan and ethylenediamine tetraacetic acid to obtain a solid powder mixture B, adding the solid powder mixture B into the liquid mixture A, and conducting stirring at 20-40 DEG C for 10-30 minutes to obtain the fertilizer liquid synergist. The liquid synergist with an interpenetrating network structure is prepared from natural polymers such as tobacco waste liquid, potassium fulvate, polyglutamic acid, glutamic acid and chitosan. The synergist can effectively delay the release of the fertilizer and improve the utilization rate of the fertilizer, so the pollution of the fertilizer to the environment is reduced, the sustainable development of agriculture is promoted, and the synergist has a great application prospect.