湖北省红壤与黄棕壤的粘粒矿物组成与磷,钾的固定

THE CLAY MINERAL COMPOSITION OF RED EARTH AND YELLOW-BROWN EARTH IN HUBEI PROVINCE AND ITS RELATION TO THE FIXATION OF P AND K

The clay minerals of red earth mainly consist of kaolinite and hydromicas, whilethose of the yellow-brown earth mainly consist of hydromicas, kaolinite and vermicu-lite. And all of the soils have few amount of 14(?) intergradient minerals. According to the experiment, the free iron oxides and hydroxyl aluminium of thesoils are the main carriersin fixing P, while the fixing power of kaolinites is smaller. As for the fixation of P in red earth, the fixing power of hydroxyl aluminium ishigher than that of free iron oxide. But in yellow-brown earth, the result turns outcontrary to the above-mentioned conclusion. To the fixation of k, the fixing powerof yellow-brown earth is higher than that of the red earth. The hydroxyl aluminium is favourable for the fixation of P, but is unfavourable forfixation of K. This effect is proportional so the content of 14(?) intergradient mille-rals as well as the heat-stable ability in soil clay fraction.