From the point of view that studies on the roots of crop plants should be made in relation to soil conditions, the authors have made several experiments, one of which is presented here. In this experiment the effects of the distribution of nutrient salts among different layers of the soil on the growth of upland rice plants were studied, when conditions of air and water supply were maintained uniformly good in all layers of all plats. Containers of galvanized iron sheeting, 25 cm. in diameter and 1 m. in depth, were filled with soil. The soil columns in the containers were divided into four layers, 20, 20, 30 and 30 cm. thick from the surface to the bottom, inserting thin sheets of paraffin wax, which allowed the passage of roots but not of water and salt solution. The surface of the soil was also sealed with paraffin wax to check the evaporation from the soil surface. Each layer was auto-irrigated after the LIVINGSTON method under a suitable hydrostatic pull. Thus the moisture content in each layer was maintained in a moderate degree and practically constant, and the amount of water transpired and absorbed from each layer by the plant could be determined by the loss in the water reservoir of the irrigator. Fertilizers were applied at the following rates, mixing with the soil of each layer before filling: (snip) Placing the containers in a glasshouse, an upland rice plant was grown in each.