Vegetative growth enhancement of organic fertilizer from anaerobically-treated palm oil mill effluent (POME) supplemented with chicken manure in food-energy-water nexus challenge

Abstract

Generally, chemical fertilizers are given priority when maintaining soil fertility. Due to the price hike of chemical fertilizers and the growing environmental concerns, more and more industries have considered developing a more economical and environmental-friendly substitutes. The oil palm industry is no exception. Efforts are put forth to recover fully the various potential palm oil milling by-products, which are abundantly generated, particularly the palm oil mill effluent (POME) for integration with food-energy-water nexus. This study attempted applying the raw (untreated) and anaerobically-treated POME supplemented with chicken manure as an organic fertilizer for Ipomoea aquatica (kangkung) growth via pot assay. Four treatments — raw POME:chicken manure at ratio (A) 1:1 w/w and (B) 2:1 w/w, and treated POME:chicken manure at ratio (C) 1:1 w/w and (D) 2:1 w/w were used. Chicken manure was added to fulfill the plant’s nutrients requirement (N:P2O5:K2O=136:141:674, kg/ha) for optimum growth. Results showed significantly greater fresh biomass (>50% increment), plant height and leaves number in treatment (C) than control and other treatments (p<0.05). Contrarily, treatments (A) and (B) caused retarded growth due to high residual oil (12.6g/L) in raw POME. Although the treated POME could enhance soil fertility, an overdose loaded with>0.58g/L volatile fatty acid, though with negligible oil residue, may affect plant growth too. As the treated POME exhibits substantial NPK nutrients, it can be conditionally used as a low-cost alternative to complement the widely used chemical fertilizers. The findings of this study offers a potential integrated approach using a local agricultural by-product (POME), producing biogas, recycled water and organic fertilizer, in meeting nexus resources demand and conserving the environment for a circular economy.