Controlled release fertiliser as an alternative nutrient management strategy for immature oil palm establishment on steep terrain: growth and foliar nutrient responses.

Introduction: Controlled-release fertilisers (CRFs) are increasingly considered a viable alternative to conventional fertiliser management in oil palm plantations, particularly in topographically challenging environments. However, their efficacy during the early establishment phase under steep terrain conditions remains insufficiently documented. Methods: A field trial was conducted using a randomised complete block design (RCBD) to evaluate the effects of different CRF rates and fertiliser regimes on immature oil palms over the first 12 months after planting (MAP). CRF was applied as a single annual basal dressing at 500 g, 700 g, and 1,000 g palm Results: Vegetative growth parameters were generally not significantly different among treatments, except for rachis length, which varied significantly (p < 0.05). Foliar nutrient concentrations showed greater response, with significant treatment effects observed for N, P, K, and Mg at 6 MAP, and N, P, and K at 12 MAP, while foliar B and rachis K were not significantly affected. CRF at 500 g palm Discussion: These findings indicate that single-application CRF can sustain early oil palm establishment under hilly terrain conditions, providing comparable performance to conventional fertilisation during the first year after planting.