Pedosphere 4(4): 363--375, 1994
ISSN 1002-0160/CN 32-1315/P
©1994 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Characteristics of oxides in argillic soils of warm temperate zone in China |
| AI Sui-Long and WEI Qing-Feng |
| Department of Soil Science, Northwestern Agricultural University, Shaanxi 712100 (China) |
| ABSTRACT |
| Studies of seven typical soil profiles showed that in the argillic soils derived from loess in the warm temperate zone of China all the oxides of Fe, Mn, Al and Si were enriched with the accumulation of clay fraction in the profiles. But owing to the influence of oxidation-reduction process, the migration velocity of Fe and Mn was faster than that of clay. The free degrees of those metals were in the sequence Mn>Fe>Al, which reflected their different chemical activities in soil. In soils at the same level of development, the free degree of iron and its activity, the free degree of Al, Alo/Alt× 100, SiO2/R2O3, Sio/Sit× 100, and the magnetic susceptibility were relatively close to each other respectively. It might be considered that both the free degrees of Fe and Al and Alo/Alt× 100 could serve as the distinctive indexes for argillic soils in warm temperate zone. The paleoclimate corresponding to the fifth layer of paleosol (s5) in Luochuan, Shaanxi was warmer and more humid than the present, and the paleoecological landscape approximated to today's bioclimatic belt between the temperate deciduous broadleaved forest and the semiarid forest types. The Mössbouer spectra of the colloidal fraction (<1μm) in the clayified horizon of argillic dark loessial soil, cinnamon soil, brown earth and (s5) paleosol indicated the superparamagnetic state at room temperature. The magnetic splitting six line spectra were observed clearly at 80 K. The results fitted with a computer showed that hematite and goethite were predominant in iron oxides and commonly existed as fine particles. The proportion of hematite and goethite in soil colloids varied considerably with different climates. The higher the temperature, the larger the proportion of hematite. |
| Key Words: free degree of Fe, Mn and Al, oxides, warm temperate zone |
| Citation: Ai, S. L. and Wei, Q. F. 1994. Characteristics of oxides in argillic soils of warm temperate zone in China. Pedosphere. 4(4): 363-375. |
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