奄美燐砿に関する研究(第1報) : 与論島燐礦とその水稲に対する肥効について

概要

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The Amami-phosphates are mined mostly in Yoron-jima. Yoron-jima is situated at the southern extremity of the Amami Islands, and 535 km. S. SW from City Kagoshima. Being measured about 23 km. round and 21 square km. in area, the island is flat enclosed by coral reefs. At the western point near the central hills this island is divided into two blocks of east and west by the NlO°W fault line fallen in west. In the eastern block, several intermittent, raised coral reefs (Ryukyu limestone) are arranged eccentrically from the central hills to the north-eastern beach. Guanophosphates are found in those raised coral reefs, but not in their reef flats. As guanos had been flowed down into cracks of limestones or closed stalactile grottos, the deposits of phosphates had been produced, and there are a few phosphates which contain 25-30% P_2O_5,but many ones contain 15-20% P_2O_5,and have special charactaristic which flourine content is extremely small ; that is 0.491-0.23% F. Judging from growth and yield of rice plants, there is no statistical difference between the nutrient value of the Amami-phosphates and that of the superphosphate.
鹿児島大学の論文