Co-benefits from applying co-digester's bio-slurry to farming activities in the Mekong Delta

Abstract

The Mekong Delta of Vietnam located in tropical monsoon area where produce such of agriculture plants and biomass sources. Due to temperatures are high all year round, water hyacinth is a highly biomass flora which was proof as a confidence source for biogas production. In the Mekong Delta, there were several studies on co-digestion water hyacinth and pig manure not only to produce more biogas but also to maintain the biogas plant in case no pig manure feeding. This investigation studied on applies the effluent from co-digester of pig manure and water hyacinth as organic fertilizer for Leaf mustard planting and as feeding for Tilapia fish growing. The results showed that the harvest yield of Leaf mustard fertilized by effluent from co-digester was 2.2 times higher in the treatment supplied with inorganic fertilizer. In addition to its contribution to higher yield of the plant, the effluent can remain more nutrients for soil layer, accelerate the flower formation that shortening cultivation time. For Tilapia fish culture, the experiments supplied with 50% bio-slurry + 50% commercial food produced the net production of fish of 43.81 and 51.92 kg.ha-1.day-1 in treatment of pig manure, of pig manure and water hyacinth, respectively. These growing rates were not significantly different to the treatment of fish culture with 100% commercial food. The results strongly confirm that the effluent from a co-digester of pig manure and water hyacinth is possible to use as organic fertilizers not only for vegetable planting but also for fish culture. By co-digestion, husbandry people could invest for a biogas system without any fearless on lack of pig manure feeding. This will bring a co-benefit on hygiene conditions to local communities due to less of husbandry waste freely discharge into open sources.