Dry matter accumulation and its distribution in various parts of corn plants at different levels of phosphorus fertilizer application were traced at the interval of 15 days throughout growing season. The results are as follows. 1. The process of dry matter accumulation of corn plant can be divided into four reasonable distinct periods by the different rates of dry matter accumulation. These are the periods of : (1) slow dry matter accumulation, (2) gradual dry matter accumulation, (3) rapid dry matter accumulation, and (4) dry matter accumulation in grain. 2. A heavy application of phosphorus fertilizer increased not only the total dry matter yields but also grain/stover ratio.