The effect of indigenous organic fertilizer on paddy field methane emissions

Paddy fields are known as one of the dominant sources of CH₄ emissions that plays an important role in greenhouse gas emissions that lead to global warming. The selection of fertilizer type may change these emissions, but whether or not using local resources such as indigenous organic fertilizer can reduce CH₄ emissions is still unknown. This paper studied the effect of indigenous organic fertilizer compared with various fertilizers on methane (CH₄) emissions at paddy fields and its relationship to the paddy growth by utilizing local resources. This research used a closed-chamber method and linear regression analysis. The planned experiment was conducted in a randomized block design pattern with five treatments and repeated four times, namely, (1) no fertilizer/control; (2) inorganic fertilizer; (3) cow manure compost; (4) indigenous organic fertilizer; and (5) commercial fertilizer. The CH₄ gas was collected at 31, 61, and 91 days after transplanting (dat) and observed for its concentration. The results showed that at 31 dat, inorganic fertilizer was the highest CH₄ flux and the lowest was no fertilizer; at 61 dat, commercial fertilizer was the highest CH₄ flux and the lowest was no fertilizer; and at 91 dat, no fertilizer was the highest CH₄ flux and the lowest was cow manure compost. Seasonal CH₄ emission rates among the fertilizers from inorganic fertilizer, cow manure compost, indigenous organic fertilizer, and commercial fertilizer were 1.952, 1.884, 1.001, and 0.954 times, respectively, of that from no fertilizer. The statistical analysis showed an inverse correlation between the result of CH₄ flux and the plant height whereas the lack of a positive correlation was found between the relationship of CH₄ flux and the number of tillers. As a result, CH₄ fluxes per grain yield were acquired in the following order: inorganic fertilizer > cow manure compost > indigenous organic fertilizer > commercial fertilizer > no fertilizer with 104.14, 91.79, 67.30, 63.38, and 34.22 kg Mg⁻¹, respectively. The application of the appropriate type of fertilizer is one of the best mitigation methods to reduce CH₄ emissions in paddy fields. The results showed that total CH₄ emission from indigenous organic fertilizer was lower than that from inorganic fertilizer, and there was not a large difference between indigenous organic fertilizer and commercial fertilizer. Therefore, the use of indigenous organic fertilizer from local resources can be used as an alternative mitigation strategy to reduce CH₄ emission from the paddy field.