CONTENTS AND DISTRIBUTION OF MINERAL-FORMING ELEMENTS IN PURPLE SOILS FROM THE SICHUAN BASIN
Tian Guanglong Tang Shijia(Institute of Soil Science, Chengdu Branch, Academia Sinica, Chengdu, 610015)
The contents of mineral-forming elements in purple soils from the Sichuan Basin and their distributions in various regions, different kinds of soil and soil profiles have been studied in detail. The mean values of SiO2,Al2O3,Fe2O3,TiO2,K2O,Na2O,CaO,MgO, MnO2 and P2O5are 58.74%, 14.36%,5.85% ,0.76% ,2.42% , 1.04%,5.50 % ,2.01%, 0.08% and 0.132%, respectively. Changes of Mg, K, Fe and Ti in the purple soils are less remarkable than those of Ca, Na, Al, P and Mn. The amount of Si is highly dependent on the type of purple rock. The formation conditions of soils have significant influence on the distribution of Ca, Na, Al, P and Mn. The distribution of K, Mn and Si in various parts of the Sichuan Basin is more uniform than that of the others. The purple soils are characterized as being rich in K and Ca.