Abstract
Nitorogen fixations of Yellow and Ando soils at Iwatahara, Shizuoka prefecture, were studied, and the results obtained were as follows : A. symbiotic nitrogen fixation of Vigna sesquipedalis 1) Nodules are increased, plant growth is favored, and nitrogen in the plant is increased, by the applications of phosphorus and potassium to these soils. 2) Small application of ammonium sulphate resulted in decrease in nodules and nitrogen, but increase in the yield and the total nitrogen content of the plant. 3) Soil inoculations have remarkable effect on the fixation of nitrogen, but no effect on the nitrogen of the plant. B. Non-Symbiotic nitrogen fixation 1) the nitrogen fixing powers of these soils examined by ASHBY'S medium are poor, especially those of Ando soils are so poor as negligible. 2) The nitrogen fixing powers are increased by the application of CaO to correct soil acidity and the inoculation with germ-carrier soil.
