Recycling of biogas wastewater to organic fertilizers and influence of organic fertilizers on maize, mung bean growth and yield under the field conditions

The objective of the study was to utilize the biogas effluents to produce solid and liquid organic fertilizers, as well as evaluate their effect on the growth and yield of corn and mung beans under field conditions. For liquid organic fertilizer, biogas effluents were mixed with fish emulsion and beneficial bacteria while biogas effluents-absorbing coal slag was mixed with sugarcane filter, fishmeal and beneficial bacteria to create solid organic fertilizer. Liquid organic fertilizer was irrigated with a dose of 5 L/1000 m2 while solid organic fertilizer was applied with a dose of 1 ton/ha with 75% recommended NPK formula for maize and mung bean. The results showed that applying solid or liquid organic fertilizer formulated from biogas effluents with other amendments helped to reduce the amount of recommended NPK fertilizer by 25%, but still maintained growth and yield of maize and mungbean equivalent to the control treatment fertilized with 100% recommended NPK. In conclusion, the amount of organic matter and N, P, K in biogas effluents from biogas digesters can be utilized to produce organic fertilizers which not only help to reduce chemical fertilizers, but also solve the environmental problems and create new friendly value-added products for practicing sustainable agricultural production.