RESUMEN
Particle size is one-factor influencing zeolite's ion exchange properties. This study used natural zeolite with a particle size of ±0.147 mm and ±500 nm as a carrier for K-zeolite-based fertilizer. K in the zeolite-based fertilizer was expected to be released slowly and more effectively in supplying K for oil palm seedlings on peat soil media compared to conventional K fertilizer (Muriate of Potash, or MoP). The study was arranged using a completely randomized design (CRD) with eight treatments and three replications. The treatments tested were: (1) control/no fertilization; (2) MoP fertilizer; (3) fine-polite-fertilizer formula-1 (FPF-1); (4) fine-polite-fertilizer formula-2 (FPF-2); (5) fine-polite-fertilizer formula-3 (NPF-3); (6) micro-polite-fertilizer formula-1 (MPF-1); (7) micro-polite-fertilizer formula-2 (MPF-2); and (8) micro-polite-fertilizer formula-3 (MPF-3). K zeolite-based fertilizers generally had better effectiveness than MoP, where formula 2 (50â¯% zeolite: 50â¯% MoP fertilizer) was the best among the three K zeolite-based fertilizer formulas. There were no significantly different effects of zeolite with a particle size of ±500 nm and ±0.147 mm on the growth and K uptake of oil palm seedlings and the amount of leached K from the peat soil. This data set could be helpful for researchers who want to develop an environmentally friendly fertilizer to implement sustainable agriculture.