A technique incorporating several improvements over previous approaches was used to measure responses of plants to several patterns of phosphorus (P) distribution throughout the root zone. Nutrient solutions were moved in and out of three discrete root zones separated by Permagum barriers. Movement was accomplished by an automatic elevating platform which periodically raised solution reservoirs from a resting position to a height sufficient for flushing each compartment with nutrient solution.Root weight increases were observed in those regions where P was present in the root zone. The lower the zone of P supply, the more diminished was the response. These findings were interpreted in terms of sugar translocation and immobilization within the roots. The P and potassium contents of the roots were unaffected by P distribution patterns but calcium and magnesium contents were markedly increased in older tissues where P was present in the ambient solution. These data supported the concept that internally translocated P and externally absorbed P have apparently differing effects at a given root site because the former does not reach the site in the same quantity as the latter. P uptake data suggested that ions absorbed at one point on a root may depress the absorption at a lower point. No significant treatment effects on shoot growth or cation and N contents of shoots were observed. The P content of the shoots, however, was in proportion to the amount of root surface in contact with ambient P.