Optimization of compound NPK fertilizer dosage to enhance the productivity of 11-year-old oil palm (Elaeis guineensis Jacq.) trees (Mature planting year 8)

Abstract

Proper fertilization is a key factor in increasing the productivity of oil palm plants. However, excessive use of inorganic fertilizers is often used by farmers. This study aims to determine the optimum dose of NPK fertilizer and its effectiveness in increasing oil palm productivity. This research was conducted from November 2023 to October 2024. The study used one-factor Randomized Complete Group Design, P0 = control, P1 = standard fertilizer Urea 2.8 + SP-27 2.4 + KCl 3.4 + Kiserit 1.5 (kg plant-1 year-1), compound NPK fertilizer treatment (P2 = 3.1 kg, P3 = 6.2 kg, P4 = 9.3 kg, P5 = 12.4 kg (plant-1 year-1)). Observations were made on the number of midribs, sex ratio, leaf tissue nutrient content, fresh fruit bunch weight, number of fresh fruit bunches harvested, average basket weight, productivity, and nutrient balance calculation (N, P, K) of plants. Furthermore, fertilizer effectiveness is calculated using Relative Agronomic Effectiveness. The use of compound NPK fertilizer dose (13-8-27+4MgO+0.65B) of 9.3 kg plant-1 year-1 (P4 treatment) increases the weight of fresh fruit bunches, average basket weight and productivity of 11-year-old producing oil palm plants (TM 8), so that the optimum dose obtained quadratically is 8.42 kg plant-1 year-1. The highest compound NPK fertilizer effectiveness value was 120.65%, meaning that it was able to increase yield 1.2 times greater when compared to the standard treatments.