南疆干旱土的成土条件与石膏的聚集

本文探讨了南疆干旱土石膏的聚集和成土条件之间的关系。结果表明:南疆干旱土区雨量小,对现代石膏聚集的影响不大;石膏含量和形态与母质类型有关,不受质地的影响;石膏层常发生在洪积扇的上部,稳定的高阶地,时间较长,是一种地质形成物。     

我国北亚热带白浆化土壤矿物学特性的研究

本文对北亚热带地区七个白浆化土壤的原生矿物和次生矿物的特性进行了研究。重，轻矿物含量表明土壤继承了母质的特性，粘淀层与漂白层的母质沉积是间断的，前者风化强度大于后者。石英颗粒表现特征显示漂白层物来来源于黄土物质再堆积，粘土矿物以水云母为主，其结晶度较差，氧化铁类型以针铁矿和赤铁矿为主，也有非晶质氧化铁和硅酸盐中的Ｆｅ＾２＋，其形成条件与现代化成土条件一致。     

干润变性土及其结核的发生学特征与形成环境探讨

干润变性土是发育于半干旱环境下的特殊土壤类型。本文以金沙江典型干旱河谷———元谋盆地发育的干润变性土及铁质结核和碳酸盐结核为例,探讨其发生学特征及其反映的土壤形成环境。土表的铁质结核和碳酸盐结核在矿物组成、微形态等特性与下伏的干润变性土有成因上联系,但两类结核与干润变性土、干润富铁土等在元素含量组成差异明显,并具有不同的形成过程和环境;微地貌陡峭、排水迅速的干润变性土地表环境残留铁质结核,而在地表平坦或低洼的干润变性土地表环境下,径流速度慢,多形成碳酸盐结核。     

海南砖红壤的微形态特征以及南方网纹红土与砖红壤环境意义的差异

主要运用土壤微形态学、粘土矿物学和土壤化学方法,对海南岛三个不同母质的砖红壤剖面的微形态特征和成壤过程进行研究,并将网纹红土和砖红壤进行比较.结果表明,砖红壤典型的微形态特征为易风化矿物颗粒和粘粒胶膜的缺失、均质状的b-垒结以及风化成因铁锰质结核的出现;典型的成壤过程为强烈的化学风化、红化、均质化、淋溶以及显著的脱硅富铝化过程.随着成土母质和土壤排水条件的变化,砖红壤的微形态特征亦有所差异.而我国南方的网纹红土的发育程度低于砖红壤,不宜被划分为砖红壤或氧化土,而更趋向归入老成土,在我国土壤发生学分类中大致相当于红壤.     

青藏高原石膏寒漠土的发生特点

寒漠土分布于我国青藏高原西北部的高寒荒漠带,它是在冰冻过程制约下形成的荒漠土壤,具有颗粒粗、粉粒和铁在表层(亚表层)聚积、有机质积累少等发生特征。石膏寒漠土除有上述特征外,还有石膏强烈聚积,因此,它通常有三个基本发生层:(1)孔状结皮层,厚度1-4厘米,多孔、呈片状或鳞片状;(2)铁质化紧实层,位于结皮层之下,厚度3-5厘米,游离铁,活性铁和粘粒含量高于上下土层,块状结构;(3)石膏层,厚度10-20厘米,石膏含量12-25%,最高达40%,结晶形态良好。根据寒漠土中具有典型的石膏层这一发生特征,拟划分出石膏寒漠土亚类。     

江淮流域白浆化土壤的矿物组成与化学特性的研究

对采自江淮流域的7个典型白浆化工土壤剖面不同粒级的矿物特性与化学组成进行了研究。结果表明：该区域白浆化土壤的质地为粉砂质壤土及粘壤土，粉粒含量为45%～76%。粘粒矿物以水云母为主，含量为60%～80%，继承了黄土母质的特性，土体硅铝率（Sa)与硅铁铝率（Saf）分别为7.70～14.05与6.43～10.24，而粘粒的分别为3.53～4.22和2.40～3.35。各剖面土体Sa与Saf以表层较高或最高，有明显富硅现象；而粘粒的Sa和Saf及矿物组成，颗粒组成的层次差异则表现出母质层次上的不连续性，白土层与粘化层的显著分异是由于全新世黄土性沉积物，经过冲积淤积交替更迭，加上后期淋溶淀积而成；脱硅、脱盐基和富铝化及氧化还原淋溶淀积是其重要成土过程，后一过程不同的利用方式，强度有所差别，以水稻土较强。     

土壤碳酸盐间接测定方法研究及其应用

通过添加CaCO3内标法及与中和滴定法进行比较,提出了采用C/N分析仪测定的土壤总C量与重铬酸钾氧化法测定的有机C量差值估算土壤碳酸盐含量的方法。采用该方法对广西环江县喀斯特低山区石灰岩发育的土壤和湖南沅江平原湖区湖积物形成的土壤的碳酸盐含量进行了分析。结果表明,石灰岩发育的土壤,林地、旱地和稻田含碳酸盐的土样占总土样数的比例依次为50.0%、43.7%和2.1%,其土壤碳酸盐平均含量分别为134、15.7和37.1g/kg。湖积物形成的土壤,新垦旱地、熟化旱地和稻田土样100%含碳酸盐,其土壤碳酸盐平均含量分别为73.3、46.6和37.7g/kg。成土母质和土地利用方式对土壤碳酸盐含量有明显的影响。     

城市道路区土壤的磁学性质及其发生学意义

土壤磁学性质测定简便快捷,且具有特定的土壤发生学意义。本研究以南京市主城区11个道路土壤剖面共63个样品为研究对象,通过对低频磁化率和频率磁化率2个常用磁学性质以及土壤游离铁、活性铁、颗粒组成、有机碳、pH、碳酸钙相当物等土壤发生学特性的测定和相关性统计分析,结果表明:城市道路土壤磁性矿物来源和成土过程具有多样性;磁性矿物主要来源于燃煤飞灰、汽车尾气中的粗粒磁性矿物,其中可能伴生污染物质的输入;较高的pH和碳酸盐不利于细粒磁性矿物的形成。城市土壤磁学性质与其他发生学特性的系统研究,有利于阐明城市土壤的形成过程。     

黄土高原典型土壤矿物固定态铵变化的南北差异

采集从北向南依次分布的干润砂质新成土(神木)、黄土正常新成土(延安)和土垫旱耕人为土(杨陵)等典型土壤剖面0200.cm土层土样,通过测定土样全氮和矿物固定态铵,以阐明黄土高原典型区域土壤全氮和矿物固定态铵及二者比率随地理位置和土层的变异规律,为全面了解黄土高原土壤相对稳定氮库累积提供科学数据。结果表明,不同地理位置、不同土层全氮和矿物固定态铵含量存在显著差异。从南到北全氮和矿物固定态铵呈下降趋势,但各土壤全氮和矿物固定态铵的分布显著不同,全氮含量在060.cm随土层深度增加下降很明显,60120.cm有一定下降,120.cm以下低而稳定。矿物固定态铵在全剖面上的分布比较均匀,随土层深度的变化差异不显著,不同土层间的差异基本在误差范围内,土垫旱耕人为土、黄土正常新成土和干润砂质新成土表层(010.cm)矿物固定态铵平均含量分别为215.807.45、165.808.73和146.501.83.mg/kg,表层以下(10200.cm)平均含量分别为193.409.67、157.145.75和142.025.47.mg/kg。从地理位置分析,干润砂质新成土、黄土正常新成土和土垫旱耕人为土表层(010.cm)矿物固定态铵占全氮的百分比分别为(39.570.78)%、(32.916.82)%和(29.747.01)%;在表层以下所占比例更高,干润砂质新成土10200.cm土壤矿物固定态铵含量占全氮比例为(89.5213.42)%,黄土正常新成土为(59.5213.86)%,土垫旱耕人为土为(47.269.01)%。供试土壤中矿物固定态铵与0.01.mm物理性粘粒含量存在极显著正相关关系,说明物理性粘粒是矿物固定态铵的主要载体;矿物固定态铵与全氮含量也有极显著正向相关性。以上结果揭示,在黄土高原黄土母质上形成的土壤,全剖面矿物固定态铵相对均匀,而有机氮相差较大,两种氮库的这种地理位置和剖面分布特征,是黄土母质形成的必然结果,也进一步支持了黄土高原黄土母质的风成学说;同时也反映了需要对有机氮占全氮比例及矿物固定态铵在全氮中地位的传统观念予以重新评价。     

北京地区红黏土碱性特征及其成因分析

以北京地区非碳酸盐母质上发育的2个红黏土剖面为研究对象,其微形态结构特征、剖面理化性质结果显示:土壤形成于古时湿热气候条件下,已基本脱钙,母质本身也不含有碳酸盐,但却表现中性至微碱性、土体内残存有微量的Ca CO3、交换性盐基离子以Ca2+为主、盐基高度饱和的碱性特征。这种碱性特征是由于现代黄土降尘所带来的碳酸盐参与到成土过程中造成的。土壤是成土因素综合作用下的产物,随着成土因素与成土过程的不断变化,应从动态发展的角度去认识和理解土壤发生学理论,才能够正确的解释土壤成土过程与土壤特性的形成原因。     

Effect of matrix composition on carbonate nodule crystallization

The mechanism of carbonate nodule formation in three soil profiles of different texture was elucidated by the application of several methods: petrographic microscopy, electron microprobe, and scanning electron microscope analysis. The profiles chosen for detailed investigation included: a loessial Serozem overlying a buried soil developed on calcareous sand in the semiarid climate of the northern Negev, Israel (EH); a polygenetic Husmas soil with secondary carbonate enrichment in a leached red mediterranean sandy clay loam from the southern Pleshet, Israel (GA); a brown Grumusol with carbonate nodules in the lower horizon from the Zebulon valley, Israel (GR).Three kinds of carbonate nodules were distinguished according to their morphology and origin: (1) orthic nodules, which have skeleton grains similar to the surrounding soil and a gradual transition to the soil matrix — these are formed in situ; (2) disorthic nodules, which on the basis of their sharp boundaries can be judged as having been subjected to some pedoturbation but have a fabric resembling the surrounding matrix; and (3) allothic nodules, which have a fabric that differs in composition from the soil in which they are incorporated and are thus judged to have been transported into the soil.This study indicates that the orthic nodules in the loessial Serozem and in the buried soil have been formed by gradual precipitation of carbonate in the microvoids of the matrix resulting in greater density and a partial expulsion of the non-carbonate clay to the fringes. X-ray spectroscopy traverses and cathode-ray distributions of the Al, Mg and Fe by microprobe indicate the presence of clay in the nodule and its gradual increase towards the still active fringes. In disorthic nodules no such increase toward the fringes was observed.Observations with the scanning electron microscope (SEM) indicate a diameter of 1.5–4 μ for the microcalcite in the Serozem and 4–7 μ for that in the buried sandy soil. Both are layered and built up from oval subhedral crystals 0.2–0.6 μ in size, a morphological type which has not been reported previously.From a detailed study of these profiles and from comparisons with some other soils, the authors conclude that the size and growth of the calcite crystals in the nodule is determined by the matrix composition, in particular by the presence of clay minerals. In a coarse-grained sandy matrix, microsparite and sparite precipitate, thus filling the voids. Similarly the vughs between the carbonate-free stable and compact peds of the Grumusol serve as good sites for the crystallization of a sparite fabric. On the other hand, the presence of dispersed clay minerals in the calcareous Serozem soil offers a large number of nucleation points for the formation of a micritic fabric, which then occludes part of the clay minerals. The presence of the clay retards and possibly even prevents a subsequent growth and recrystallization of the calcite crystallites.     

黄土地区非代换性钾与土壤发育的关系

黄土地区土壤类型和发育程度与土壤非代换性钾有关。本文初步研究了黄土地区主要土壤类型非代换性钾的变化。影响土壤非代换性钾含量和释放累积量的主要因素是土壤质地和有机质。粉砂粒、粘粒和有机质与非代换性钾呈正相关,而砂粒与非代换性钾呈负相关。土壤非代换性钾含量由北向南从66.71-84.62增到117.09-129.95mg/100g土;释放累积量由北向南从147.03-173.00增到251.18-346.08mg/100g土。说明黄土地区土壤非代换性钾的含量和释放累积量均从北向南逐渐增加。砂绵土和黄绵土,砂黑垆土和轻黑垆土的非代换性钾含量和释放累积量其剖面分布较均一;而粘黑垆土和黑(土娄)土的粘化层的非代换性钾含量和释放累积量高于耕作层和母质层,但因地形部位不同又存有一定差异。     

The origin and early genesis of clay bands in youthful sandy soils along lake Michigan,U.S.A.

A beach ridge and dune complex with good radiocarbon control sampling the last 3500 radiocarbon years B.P. provides new insights on the early genesis of clay bands in sandy soils. Soil profiles were sampled by age groups, described in the field, and then subjected to laboratory analyses for particle-size distribution, pH, organic carbon, carbonate minerals, and extractable iron and manganese. This study suggests that small increases in pH, brought about by small increases in carbonate content within the soil profile, are responsible for flocculating small amounts of illuviated clay. This process, along with a transition to a greater hydraulic conductivity with soil depth due to coarser textures in any given profile, partly explains the existence and possible reason for the initiation of illuvial zones and eventually for clay-band horizons. A pronounced increase in the thickness of incipient clay-band horizons in soils older than 2300 years appears due to finer textures in the parent materials than are present in younger soils. Because of slightly reduced porosity and lower permeability, carbonates and a high pH are retained in both illuvial and eluvial horizons of some of these older soils. In addition, only in those profiles older than 2300 years do clay and iron oxide concentrations coincide and is there some suggestion of greater amounts of extractable manganese in horizons of minimum iron and clay. A pronounced segregation of clay-iron bands is not apparent at the study area but should occur in future years as additional amounts of iron and clay are deposited.     

Podzolization and clay migration in spodosols of eastern France

Field observations and laboratory analyses of podzols developed on sandy Triassic parent material in the Vosges have demonstrated clay accumulation in the upper parts of spodic horizons, especially in the B_h horizons. To see whether clay accumulation corresponds to real clay illuviation, two types of podzol profiles have been studied. The first is an iron podzol, called “podzol forestier”, because it has been entirely developed under climax forest environment. The second, an iron-humus podzol, called “podzol de dégradation”, was first developed under forest and more recently (the last 1000 to 2000 years) under heath vegetation. Methods used in the study of the two profiles were the “isoquartz” alteration balance, clay mineral identification by X-ray analyses and micromorphholigical examination.For the podzol forestier, the data strongly support a hypothesis of illuviation of very fine micaceous clays (vermiculite), especially the ferriargillans in the B_h horizon. Consequently, it is believed that illuviation of the greatest part of clays promoted differentiation of podzol horizons. Podzolization is strongly redistributive.In the podzol de dégradation, the identified clay minerals are the same as in the podzol forestier but the pedological features in the B_h horizon correspond to those of classic spodic horizons (mixed concentration and grain coatings). Moreover, podzolization is geochemically strongly subtractive in this second type of podzol.Inasmuch as the podzols de dégradation are developed from the podzols forestiers, the authors define an evolutionary time-sequence: the first phase of forest soil genesis is regulated by the double process of clay illuviation and redistributive podzolization. The following degradation phase connected to the particular nature of heath vegetation and to abundant chelating organic compounds induces the disruption of the ferriargillans previously formed in the B_h horizon, the formation of an agglomeroplasmic fabric microstructure and above all, the elimination of hydrolyzed products of minerals from the profile. During this last phase, a strongly subtractive podzolization prevails over clay illuviation.     

Palevye (pale) soils of Central Yakutia: Genetic specificity,properties, and classification

Permafrost-affected palevye (pale) soils of Central Yakutia are developed from mantle calcareous deposits of different textures and are characterized by the common mica-chloritic association of clay minerals with a higher content of chlorite in comparison with the soils developed from mantle loams and loess-like loams in the European part of Russia. In the pale soils, the distribution of clay minerals in the profile has an even pattern in the loamy variants and a differentiated pattern typical of podzols in the loamy sandy variants. Data on the chemical extracts and Mössbauer spectroscopy indicate that the iron in the pale soils is mainly fixed in silicate minerals. The content of nonsilicate iron represented by the amorphous and weakly crystallized compounds in the pale soils is relatively low. The humus-accumulative horizon in these soils is close to the gray-humus (soddy) AY horizon according to its acid-base characteristics (the soil pH and the degree of base saturation) despite the presence of exchangeable sodium and the shallow occurrence of the calcareous horizon.     

CHARACTERISTICS OF NUBIAN SANDSTONE-DERIVED SOILS

Nubian sandstone exposures in sub-humid, semi-arid, and arid environments have given rise to red, sandy but in other respects very different soils. Soils have a fairly well developed profile only in the sub-humid zone, including a textural B horizon and are free of soluble salts and carbonates. In the semi-arid and arid zones, profile differentiation is weak or non-existent. Soils are shallow and contain carbonates, and in the arid zone also soluble salts, including gypsum. Kaolinite is the only clay mineral which is common to all the nubian sandstone parent materials. It is the major clay mineral in the sub-humid zone soil. In the semi-arid soils smectite is a second major clay component. In the arid zone both smectite and palygorskite, in minor amounts, accompany kaolinite. Both smectite and palygorskite are probably pedogenic neoformation products. Material of aeolian origin has probably been introduced into the silt and fine sand fractions of both the semi-arid and arid soils. Some contamination of the clay fractions may have also occurred.     

四川盆地紫色土肥力与母质特性的关系

紫色土在四川盆地分布最广,占全省总面积的28%,占耕地总面积的68.7%,是该省粮食生产基地,粮食产量约占全省总量的70%.这种土壤除种植粮食作物外,还适宜种植蔗、棉、油、桑和水果.紫色土生产潜力极大,但也存在不少问题.从三十年代以来,许多土壤学者对紫色土进行过一系列研究,一致认为紫色土肥力与母质特性关系密切.本文以底土或岩石风化碎屑(即母质,C)为基本材料,同时用表土(A)和岩石(R)作辅助样品,研究了紫色土肥力与母质特性的关系.