两种典型耕作土壤粘粒矿物XRD光谱特性分析

以东北粮食主产区典型耕作黑土和黑钙土为研究对象，在测定同一气候和地理位置下两种耕作土壤颗粒组成特征情况的基础上，采用X射线衍射(XRD)分析方法，对两种耕作土壤的粘粒矿物组成及相关差异进行分析，深入探讨其内在变化机理，是土壤矿物研究的新视角。结果表明：两种供试土壤颗粒组成均以砂粒为主，粘粒、粉粒次之;当颗粒累积率达到50%时，中央粒径分布在15～130 μm区间，除胜利乡黑土剖面外，各采样地两类土壤的剖面中粘粒含量的分布顺序呈现出与中央粒径大小相反的趋势。土壤粘粒在两种土壤剖面中呈现不同的分布规律，黑土剖面中粘粒在表层富集(18.82%)，而黑钙土剖面中在钙积层富集(17.41%)。除泉眼岭黑土剖面外，其余采样地的土壤剖面中粘粒含量均在母质层中最少。XRD图谱分析显示，不同土壤中粘粒矿物图谱的差异不仅表现在衍射峰的强度及部分衍射峰位的变化上，还表现在矿物组成上。黑土、黑钙土均以2∶1型粘粒矿物为主，黑土组成为蒙伊混层-伊利石-蛭石型，黑钙土为蒙伊混层-伊利石-蒙脱石型，且均含有少量的高岭石、绿泥石、石英等原生矿物。

Analysis of XRD Spectral Characteristics of Soil Clay Mineral in Two Typical Cultivated Soils

The present paper took black soil and chernozem, the typical cultivated soil in major grain producing area of Northeast, as the study object, and determinated the soil particle composition characteristics of two cultivated soils under the same climate and location. Then XRD was used to study the composition and difference of clay mineral in two kinds of soil and the evolutionary mechanism was explored. The results showed that the two kinds of soil particles were composed mainly of the sand, followed by clay and silt. When the particle accumulation rate reached 50%, the central particle size was in the 15～130 μm interval. Except for black soil profile of Shengli Xiang, the content of clay showed converse sequence to the central particle in two soils. Clay accumulated under upper layer(18.82%)in black soil profile while under caliche layer(17.41%)in chernozem profile. Clay content was the least in parent material horizon except in black profile of Quanyanling. Analysis of clay XRD atlas showed that the difference lied in not only the strength of diffraction peak, but also in the mineral composition. The main contents of black soil and chernozem were both 2∶1 clay, the composition of black soil was smectite/illite mixed layer-illite-vermiculite and that of chernozem was S/I mixture-illite-montmorillonite, and both of them contained little kaolinite, chlorite, quartz and other primary mineral. This paper used XRD to determine the characteristics of clay minerals comprehensively, and analyzed two kinds of typical cultivated soil comparatively, and it was a new perspective of soil minerals study.