Abstract
Sands were served as media for growth of soybeans and those previously germinated in plant- food- free sand. It was shown that calcium supply must first meet the requirement of early stage of the growth and that a certain amount of this element served efficiently to supply phosphoric acid present in small quantities. The important role of phosphoric acid was considered for the mechanism of nitrogen fixation, as has been seen little effect on soybean plants receiving combined nitrogen. Increasing calcium supply was the cause of high calcium- phosphoric acid relation in nodules, while increasing phorphoric acid was not a low relation. For securing normal development of nodules, it was suggestible to use phorphoric acid fertilizers not later than two weeks after sowing, since the infection of appropriate bacteria may take place under normal condition of soybeans as early as 14 days.
