The probable distr. of roots of fruit trees when grown on a reasonably uniform soil is shown. The permanent wilting percentage wTas reached in a certain depth of soil close to the trees as soon as it was midway between adjacent trees. A few cases were found in which, however, because of the kind of rootstock or the kind of soil, root distribution was uneven. Under conditions of soil and root distribution similar to those in this series of expts. reliance can be placed on a system of soil sampling during the growing season for the planning of an irrigation schedule. If the soil is variable or if there is unequal distribution of roots, irregularities in soil moisture of considerable magnitude occur. Relative wetness will not aid in interpreting results when root distr. is not uniform. The fact that soil samples taken at any place within the exptl. plots in mature peach, prune, and walnut orchards, which have had an even application of water, agree at comparable depths, shows that these trees under the conditions existing at Davis, have a uniform distribution of roots. Samples taken at any position between the trees may be used to interpret the soil-moisture conditions.