This research was carried out with the purpose to determine the relationship existing between the concentration of nitrogen, phosphorus and kalium in de soil and the foliar area of cucumis sativus. The plantation was made in a fersialitico rojo-parduzco ferromagnesial soil, without applying any fertilizer in a sample, and using the adecuate amount established by MINAGRI in another. At the beginning of the experiment, some analysis of the soil are carried out in order to determine the concentration of this macroelements, both in the flowering stage, during the harvest, as well as in the foliars analysis during the last two stages (flowering and harvest). As a result of the evaluation of such analysis it was evinced that cucumis sativus demands lots of kalium, macroelement taken from the soil and which is not preserved at a high proportion in the foliar area.