Development and evaluation of controlled release fertilizer using P (3HB-co-3HHx) on oil palm plants (nursery stage) and soil microbes

The scope of this study was to formulate polyhydroxyalkanoate (PHA)-based controlled release fertilizer (PHA-CRF) for oil palm (nursery stage) by using biologically recovered poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and oil palm trunk vascular bundles combined with commercial NPK fertilizer. The efficiency of PHA-CRF was measured based on plant growth parameters such as plant height, number of leaves, chlorophyll content, stem thickness and fresh biomass. The release of the fertilizer in soil was monitored by electrical conductivity measurement. As expected, the highest electrical conductivity was recorded for the soil amended with immediate release fertilizer (IRF) which was 847 mu S/cm compared to the soil amended with various combinations of CRF which were all less than 90 mu S/cm. In terms of plant growth, PHA-CRF resulted in plants with similar heights to those amended with commercial CRF and IRF. In addition, the total fresh plant biomass was higher when PHA-CRF was used to amend the oil palm planting soil. Moreover, the degradation of PHA observed for PGVFB, PRVBF and PRVB was 61%, 47% and 27% after three months of application. The PHA degradation results confirm the enrichment of bacterial and fungal communities in oil palm rhizosphere with the addition of fertilizer in the formulations.