Introduction Agronomic research has a growing interest in collecting faster, cheaper and still efficient information about agricultural matrices in order to achieve a better monitoring of soil quality and fertility1. Laser-induced breakdown spectroscopy (LIBS) and X-Ray fluorescence spectrometry (XRF) have been identified as high potential techniques for on-site multi-elemental analysis of agronomic matrices such as plants2 and soils3. Materials and Methods The study of agricultural soils and plants, more precisely the multi-elemental quantification of several chemical elements of interest (P, Mg, Fe, Al, Ca, K…), was realized using portable LIBS (Z300 – SCIAPS) and portable XRF (S1 TITAN 800 – Bruker) systems. 62 soil samples and 40 plant samples have been prepared as pressed pellets. Multivariate calibrations have been achieved for quantitative analysis of the LIBS spectra. Both XRF and LIBS quantitative analysis were compared to the concentration values determinate by ICP OES. Results and Discussion Good practices related to sample preparation and experimental conditions to achieve relevant LIBS/XRF measurements in laboratory will be discussed. For both LIBS and XRF measurements, the influence of environmental parameters has been examined in order to assess the robustness of on-site analysis. Finally, a first campaign of on-site LIBS and XRF analyses on agricultural soils and plants has been performed. Conclusion The evaluation in the laboratory of two portable instruments, LIBS and XRF, on soils and plant samples, have revealed that these two techniques are very sensitive to moisture. The results of the field measurements on wheat leaves and soil will be presented and discussed.