Abstract
In the previous report, writers proposed a method by which they determined the most adequate amount of nitrogen to be given to rice plant in a paddy field condition.Our intention of this study is to determine the amount of phosphorus to be given to rice plants by the same method. The weather of the year (1948) when this experiment was carried out, was extraordinary favorable for the growth of rice plant.And the manurial effect of phosporic acid was not manifested well as compared with the ordinary year.So, there would remain many points to be discussed, but we may conclude the following results. 1)If we make a graph (as shown in Fig.3) which sows the relation between the amount of the grain produced and the percentage content of phosphorus in the grain at a given amount of phosphorus application, only one stage is recognized from the graph, this stage is the excess stage.So, it seems there is no lack of phosphorus in this field. 2)However, in the case of no phosphorus plot, about 13 kg P_2O_5 per acre was absorbed from the soil by rice plant. 3)The main variation of rice constituents according to the increment of phosphorus application are the decrease of starch content and the increase of crude protein and crude fat content.
