三江平原白浆土发生学特性

PEDOGENETIC CHARACTERISTICS OF ALBIC SOILS INTHE THREE RIVER PLAIN, HEILONGJIANG PROVINCE

本文对三江平原三个典型白浆土剖面的理化性质、土壤微形态和矿物学性质的研究，探讨了白浆土的发生学特性。土体中Ｚｒ／Ｓｒ和Ｔｉ／Ｚｒ比率的变异系数表明，所研究的土壤剖面其成土母质岩性是连续的。典型白浆土是具有一个松软的表土层、一个漂白层和一个相当厚的粘化淀积层。研究还表明，粘粒的悬浮迁移是白浆土的主要成土过程。表层和白浆层在成土过程中有Ｆｅ－Ｍｎ结核形成，且是原地形成的，其Ｆｅ、Ｍｎ明显源于原生矿物的风化。淀积层中部土壤的焦磷酸盐提取的Ｆｅ、Ａｌ及草酸铰和连二亚硝酸钠提取的Ａｌ出现最大值。焦磷酸盐提取的Ｆｅ、Ａｌ与粘位量之比为０．０１，有机碳与焦磷酸盐提取的Ｆｅ之比为２．７—３．３，均小于灰化淀积层的指标。土壤ｐＨ值在剖面上下变化不大为４．５—５．０。土壤粘粒组分中粘土矿物是以蛭石为主，这和以前研究的以水云母为主有所不同。土壤剖面上下粘工矿物类型基本相似，仅在数量上有所不同。所研究的土壤按ＦＡＯ—ＵＮＥＳＣＯ分类应命名为松软粘盘土，按美国土壤系统分类为典型粘淀漂白软土。

ith the study of physical, chemical, morphological and mineralogical Propertiesof three pedons of typical albic soils from the Three River plain of HeilongjiangProvince, we discussed the pedogenetic characteristics. The profiles were found to belithologicaliy countinuous by the comparsion of Zr/Sr and Ti/Zr ratio within thepedons. The albic soils study was characterized by a mollic epipedon, an ablic Ehorizon and a thick argillic horizon. Through this study, it was indicated that lessi-vage was a dominant pedogenetic process. Pedosmenic Fe-Mn nodules were foundabundant in Ah and E horizons and were apparently formed by weathering of Fe-Mn primary minerals, and the nodules may have deveioped in situ. The maximumamounts of pyrophosphate extractable Fe and Al appeared it Bt2 horizons were sma-ller than the values required for podzols. Vermiculite, which had not previouslybeen recognized, dominated the clay fraction of albic soils. The clay mineral asse-mblage was qualitatively similar but quantitively differentiated throughout the pro-file. Finally, we suggested that the albic soils could be classified as mollicplanosols in the FAO-UNESCO system and Typical Argialbolls in Soil Taxonomy.