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Compost derived from mix manures, shopped Leucaena leucocephala de Wit, bran of rice, molace, fish fermented juice were studied their humification process by using humic acid quantity and its functional groups, which were phenolic and carboxylic groups. Samples were collected for all analysis at day 0, 7, 14, 21, 28, 35, 49, 63, 77, 91, 105, and 119. The results showed that the maturity of compost could be divided into 4 steps — the initial phase (day 0), thermophilic phase (day 1–34), end of active phase (day 35), and mature compost (36 days up). After 35 days of mixing, the highest amounts of humic acid, 280.1 mg/g occurred and was higher than the others 4.7–19.9 folds. The relationship of the amounts of phenolic acid during the period of mixing significantly correlated with the total acidity and showed the highest amounts at day 35 as well (r = 0.98; p 0.01). Pearson correlation coefficients among the four major elements of humic acid: carbon (C), nitrogen (N), oxygen (O) and hydrogen (H) showed that the amounts of O significantly negatively correlated with C and H while C and H were significantly positively correlated to each other (r |
