KCl fertilization is generally done to increase the productivity of porang tubers, but the continuous use of KCl can degrade soil fertility. Based on this, KCl needs to be replaced with organic fertilizer. This research aimed to determine the effect and replacement of KCl with organic fertilizer which caused the highest porang yield. The research was held in the BKPH Pojok forest area, Grobogan, Central Java in March-July 2020. The research was using one-factor RCBD. This treatment was the replacement of KCl with organic fertilizer with percentage 100:0%, 75:25%, 50:50%, 25:75%, 0:100%, and control in 4 replications. Observation parameters included tuber fresh weight, tuber storage weight, tuber diameter, tuber thickness, and tuber chip weight. The data were processed by using ANOVA 5% and DMRT 5%. The results showed that KCl had a strong influence on the yield of porang which included tuber fresh weight, tuber storage weight, and tuber chip weight, and organic fertilizer was able to replace the role of KCl. The usage of KCl and organic fertilizer was selected based on the yield of the highest tuber diameter and thickness and appeared with the same percentage (50% KCl:50% organic fertilizer).