The present authors continued the experiment in respect to the trouble of paddy rice plant after the manuring of am-sulphate and sulphatemanures which has been lately observed in various districts, Nippon, especially in Kagawa and Okayama prefectures, and affirmed the conclusion of previous papers [J.soc.sci.soil and manure Nippon 12. 452 (1938)and 13.I(1939).] The results of the experiment will be reported summarily as follows : I. The reduction of sulphate was lessoned. a) By controlling soil pH as to be as 5-5.5 at which the growth of rice plant will not be affected. b) By application of calcium cyanamide and controlling the reducing activity of soil. c) By renewing water of the field.II By withdrawing water as possible from the field and exposing soil-surface to air when the trouble has taken place.III. In subsoil of the troubled field, there was.no reduction observed and it was so no relatiou with the trouble.
抄録全体を表示