水稻土中针铁矿的铝同晶替代作用及其在分类上的意义

在水耕条件下,针铁矿的铝同晶替代减弱和导致水稻土中针铁矿的铝同晶替代量的明显降低,且随水稻土发育度的提高而降低。水稻土发育过程中这一变化,不仅反映了水稻土特殊的成土条件;而且反映了水稻土成土过程的特点。因此,水稻土诊断层中针铁矿的铝同晶替代量可作为划分亚类的重要诊断指标之一。据本研究结果,暂拟本区渗育型水稻土渗育层中针铁矿的铝同晶替代量为9-18mol%;而潴育型水稻土潴育层中针铁矿的铝同晶替代量则小于9mol%。

THE ALUMINUM SUBSTITUTION OF GOETHITE IN PADDY SOILS AND ITS SIGNIFICANCE ON SOIL CLASSIFICATION

This paper deals with the Al-substitution of goethite in paddy soils and their original soils. The change of Al-substitution of goethire during the develoment of paddy soils was stutdied and its significance in soil classification is discttssnd. Cinder the artificial waterlogged condition, the Al-substitution of goethite in soils was weakened. the Al-substitution of goethite in paddy soils was much less than that of their original sails, and it decreased with soil developing. The change of Al-substitution of goethite in the diagnostic horizons not only reflected the special pedogenic condition of paddy soil, but also the characterized pedogenic process, So, it can be used as one of the major indices for dividing the subgroup of paddy soil. The Al-substitution of goethite was 9-18 mol% in the percogenic horizon of percogenic paddy soil,.but it was lower than 9 mol% in the periodically,waterlogged horizon of periiodically watterloged paddy soil.