Abstract
The object of the present studies were to find method of paddy fertilization in fields damaged by flood. The studies are classfied into the following, 1) The establishment of experiment plots on paddy field. 2) Growth survey of rice plants. 3) Research on the farm-management of farmers whose field were damaged by flood. 4) Soil survey and physico-chemical analysis of paddy soil just after rice-harvest. The results obtained were as follows, 1) In the early growth at ages, root initiation was belated in flood-damaged fields, and accordingly, leaves were light green in colour. But the lodging was very frequent due to excess of nitrogen liberated thereafter. 2) The muds accumlated by flood were mostly fertile heavy clay or clay loam. At the accumlated layers from 5 to 10 inches nitrogenous fertilizers must not be used. When NH_4-N by ammonification are more than 10 mg per 100 g of air dried soil. 3) Effect on rice yield of phosphorus and potassium fertilizers was little. 4) If the amounts of NH_4-N by ammonification were less than 7〜8 mg per 100 g of soil, from 1 to 1.5 kans of ammonium sulfate must be applied as base-fertilizers. 5) At the accumlated layers from 2 to 3 inches when the amounts of NH_4-N are more than 10 mgs per 100 g of soil, 50% of normal dressings of nitrogenous fertilizers may be applied.
