Lack of control over fertilization is one of the major factors in the yield gap between smallholders and large oil palm plantations (Monzon et al., 2023). The diagnostic tool known as leaf analysis method is used by a large number of plantations to manage their fertilization and relies on annual leaf analysis and specific long-term experiments (Dubos et al., 2022). However, this method is not accessible to smallholders, mainly due to the cost of annual leaf analysis. As a consequence, major imbalances in fertilization are generally observed. The most important nutrients to monitor in this crop are N, P, K and Mg (Woittiez et al., 2017). However, current methods to measure leaf nutrient status are long, costly and require hazardous chemical reagents. Recent developments in near-infrared spectrometry (NIRS) have made it possible to create increasingly low-cost measurement equipment, without the need to transform the leaflets (Prananto et al., 2020). We tested the possibility to use a small portable infrared spectrometer (Nirone S2.2 Evaluation Kit from Spectral Engines) in order to make fertilization management more accessible for smallholders. This spectrometer has a reduced spectral range of 1750-2150nm which has been selected in a prior study testing the correlation between leaflet contents with various spectral ranges. A total of 92 leaflets composite samples were taken from several plots of smallholders and large plantations in West Africa. The plots were located in marginal hydric conditions of Benin and in more favorable conditions of Nigeria, in plantations with different nutritional status, age and plant materials, allowing a large range of variability. Spectral Measurements were taken directly on fresh leaflets on the frond 17, using in classical leaf analysis. Laboratory measurements were got according to the standard methodology of Leaf Analysis. PLS regressions after preprocessing the spectra were used to set up predictive models for the concentration of