The soil fertility index (SFI) technologi is an assessment of soil properties and nutrient availability to support plant growth and development. The soil fertility index is very relevant in the engineering of planting media, especially on marginal land to support environmentally friendly sustainable agriculture by utilizing organic materials as soil improvers. This research contributes to crop cultivation by utilizing marginal land, by offering a method of analyzing soil fertility index and providing knowledge to oil palm farmers in utilizing marginal land as a planting medium. The purpose of this research is to analyze the fertility value of various marginal soils that will be used as planting media materials. This research was conducted in Musi Rawas Regency, South Sumatra Province, Indonesia, from November 2024 to January 2025.  This research method uses disturbed soil samples on marginal land. Composite soil samples consisting of five types of marginal soils include: ultisol subsoil with a depth of M1 = 0-50 cm, M2 = 50-100 cm, M3 = 100-150 cm, peat and entisol. The results of the comparative study of the fertility value of various types of marginal soils are almost on average low criteria, for improvement it is necessary to add organic matter as much as 1.5 - 2.5% to each planting medium and evaluate the fertility index of various types of marginal soils ranging from 80 - 100 which is categorized in the low to medium class.