Abstract
1. Clayey soil at Higashikawasoe in Saga prefecture, sandy soil at Fukuma in Fukuoka prefecture and zeolite at Yokote in Akita prefecture are found having the property of fixing large quantities of ammonium when they are dried after an ammonium choride solution is added to them. The Higashikawasoe soil is the one which is derived from marine alluvial deposits, and the Fukuma soil is the one which is originated in the granite. The ammonium fixing-power of all soils studied with exception of above-mentioned samples is observed to be very weak or none. 2. Ammonium fixing-power of soil increases with depth in the most cases. 3. Correlation coefficient between the amounts of ammonium fixed and that absorbed is calculated to be 0.69,0.05 in fifty samples studied, but it seems that the fixation of ammonium is not a phenmenon which attends always to an absorption of that ions. 4. Very small amounts of ammonium volatilize at the drying process on the water bath. 5. Higashikawasoe soil, Fukuma soil or zeolite fixes an appreciable amounts of ammonium ions under moist conditions. 6. Drying a soil after an ammonium chloride solution is added to the soil results in greater fixation than when it is kept under moist conditions.
