Establishing a method to evaluate the maturity of liquid fertilizer by liquid fertilizer germination index (LFGI)

With the ongoing growth of liquid manure production, it was necessary to build a proper certification system to check the fertilizer and pollutant qualities of manure fertilizer. The certification criteria of fertilizer and pollutant properties have been developed, but no certification method has been developed for testing the maturity of liquid manure fertilizer until now. Meanwhile, the germination index is a well-known parameter when measuring the maturity of fertilizer. Several methods are advised for measuring the germination of compost-based fertilizer. Until now, there was no specific method for certifying or performing a germination index test for liquid fertilizers. In this study, the ordinary germination index (GI) or Solid fertilizer germination Index (SFGI) is performed for 23 solid-composted fertilizers to evaluate the method's applicability when the average SFGI count is 137. However, when this method is applied to 26 liquid anaerobic manures, the average SFGI count was 22, with germination only happening for eight samples. When the LFGI method was applied for the same samples, the average LFGI count was 30 with 10 germinated samples. LFGI was applied to 66 liquid aerobic manure fertilizers that had mechanical maturity tests and were classified as 22 matured, 25 semi-matured, and 19 immature samples. The average LFGI results were 90 for matured samples, 25 for semi-matured, and 5 for immature. This study focused on finding a proper and acceptable germination index testing method to examine the maturity of liquid manure fertilizer.