Abstract
Nitrificatins in Yellow and Ando soils were studied this time. Nitrifications of ammonium sulphate in these soils were poor. The nitrifications were, not be iufluenced by the applications of phosphorus or potassium, but they were somewhat obviously affected by the use of calcium oxide to correct soil acidity and by the inoculation. Chemical oxidation of N0_2 to N0_3 was here proved to take place when NaN0_2 was added to these acid soils, but microbiological oxidation took place mainly in the nitrification when ammonium salt was applied. Poor nitrification of these soils was due to feeble nitrifing bacteria (nitrosomonas and nitrobacter) and also to the acid reaction.
