At the Instituto Colombiano Agropecuario (lCA) in Palmira, an experiment was carried out during the second semester of 1992 and first one of 1993 to determine the soybean (Valluna-5 variety) actual evapotranspiration (En under three percentages of soil water depletion (30, 50 and 70%); besides, the 50% for the soil compaction called rake foot, at about 15 to 20 cm deep. In adition, several empirical formulas and direct methods to calculate the reference evapotranspiration (Eto) were evaluated. The experiment was established under a complete block design with three repetitions. The treatment including rake foot and 50 % of soil water depletion had an ET 12.5% greater water demand ocurried during preblooming (35-39 ys) and blooming (40-59 days) stages, in all studied treatments. In a economic analysis basis, it is suggested to use the 30% of soil water depletion. However, it is possible to use as an alternative the 70% treatment every time that ghe total amount of water applied (irrigation+rain) is over 340 mm, during the first 100 days of the crop cycle. under similar conditions at the present experiment, seems reasonable to use soil water depletions between 50% and 70% for soil with rake foot, The suggested equations to calculate Eto are Penman and Garcia - Lopez and the method of the pan evaporation type A.