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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。 相似文献
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三江平原白浆土发生学特性 总被引：1，自引：1，他引：1
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 相似文献
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Elementary pedogenetic processes forming gypsic pedofeatures in gypsiferous soils are discussed. Several groups of such processes are distinguished: (1) weathering of gypsum-bearing rocks; (2) gypsum formation associated with weathering of sulfuric (pyritic) rocks; (3) precipitation of gypsum owing to the inflow of soil solutions saturated with Ca and SO4 and their evaporative concentration; (4) gypsum formation owing to exchange reactions in soils between calcium in the exchange complex and sodium sulfate solutions; (5) gypsum formation upon interaction of calcium carbonates with sodium sulfate water resulting in the loss of CaCO3 and gypsum accumulation (decalcification process); (6) colluvial and alluvial redeposition of gypsum in the landscape with its accumulation in the subordinate positions, where gypsiferous soils are formed; and (7) eolian deposition of gypsum on the soil surface with the formation of gypsum-bearing horizons. The micromorphological specificity of the gypsic pedofeatures reflects the processes of their destruction and/or accumulation in the soil profiles. It is shown that gypsum accumulation in soils is a pedogeochemical process that manifests itself in different natural zones upon the presence of gypsum sources. 相似文献
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中国土壤分类法中铁铝土的分类 总被引：4，自引：1，他引：3
The development of the classification of ferrallitic soils in China is reviewed and the classification of Ferralisols and Ferrisols in Chinese Soil Taxonomy is introduced in order to discuss the correlation between the ferrallitic soil classification in the Chinese Soil Taxonomy and those of the other soil classification systems. In the former soil classification systems of China, the ferrallitic soils were classified into the soil groups of Latosols, Latosolic red soils, Red soils, Yellow soils and Dry red soils, according to the combination of soil-forming conditions, soil-forming processes, soil features and soil properties. In the Chinese Soil Taxonomy, most of ferrallitic soils are classified into the soil orders of Ferralisols and Ferrisols based on the diagnostic horizons and/or diagnostic characteristics with quantitatively defined properties. Ferralisols are the soils that have ferralic horizon, and they are merely subdivided into one suborder and two soil groups. Ferrisols are the soils that have LAC-ferric horizon but do not have ferralic horizon, and they are subdivided into three suborders and eleven soil groups. Ferralisols may correspond to part of Latosols and Latosolic red soils. Ferrisols may either correspond to part of Red soils, Yellow soils and Dry red soils, or correspond to part of Latosols and Latosolic red soils. 相似文献
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The development of the classification of ferrallitic soils in China is reviewed and the classification of Ferralisols and Ferrisols in Chinese Soil Taxonomy is introduced in order to discuss the correlation between the ferrallitic soil classification in the Chinese Soil Taxonomy and those of the other soil classification systems.In the former soil classification systems of China,the ferrallitic soils were classified into the soil groups of Latosols,Latosoilc red soils,Red soils,Yellow soils and Dry red soils,according to the combination of soilforming conditions,soil-forming processes,Soil features and soil properties.In the Chinese Soil Taxonomy,most of ferrallitic soils are classified into the soil orders of Ferralisols and Ferrisols based on the diagnostic horizons and /or diagnostic characteristics with quantitatively defined properties.Ferralisols are the soils that have ferralic horizon,and they are merely subdivided into one suborder and two soil groups.Ferrisols are the soils that have LAC-ferric horizon but do not have ferralic horizon.and they are subdivided into three suborders and eleven soil groups.Ferralisols may correspond to part of Latosols and Latosolic red soils.Ferrisols may either correspond to part of Red soils,Yellow soils and Dry red soils,or correspond to part of Latosols and Latosolic red soils. 相似文献
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Soils formed in loess are evidence of both relict and buried landscapes developed on Pliocene-to-latest Pleistocene basalt flows of the Cima volcanic field in the eastern Mojave Desert, California. The characteristics of these soils change systematically and as functions of the age and surface morphology of the lava flow. Four distinct phases of soil development are recognized: phase 1 - weakly developed soils on flows less than 0.18 M.y. old; phase 2 - strongly developed soils with thick argillic horizons on 0.18 – 0.7 M.y. old flows; phase 3 - strongly developed soils with truncated argillic horizons massively impregnated by carbonate on 0.7 to 1.1 M.y. old flows; and phase 4 - degraded soils with petrocalcic rubble on Pliocene flows. A critical aspect of the development of stage 1 soils is the evolution of a vesicular A horizon which profoundly affects the infiltration characteristics of the loess parent materials. Laboratory studies show that secondary gypsum and possibly other salt accumulation probably occurred during the period of phase 1 soil development. Slight reddening of the interiors of peds from vesicular-A horizons of phase 1 soils and presence of weakly developed B horizons indicates a slight degree of in situ chemical alteration. However, clay and Fe oxide contents of these soils show that these constituents, as well as carbonates and soluble salts, are incorporated as eolian dust. In contrast to phase 1 soils, chemical and mineralogical analysis of argillic horizons of phase 2 soils indicate proportionally greater degrees of in-situ chemical alteration. These data, the abundant clay films, and the strong reddening in the thick argillic horizons suggest that phase 2 and phase 3 soils formed during long periods of time and periodically were subjected to leaching regimes more intense than those that now exist. Flow-age data and soil-stratigraphic evidence also indicate that several major loess-deposition events occurred during the past 1.0 M.y. Loess events are attributed to past changes in climate, such as the Pleistocene-to-Holocene climatic change, that periodically caused regional desiccation of pluvial lakes, reduction of vegetational density, and exposure of loose, unconsolidated fine materials. During times of warmer interglacial climates, precipitation infiltrates to shallower depths than during glacial periods. Extensive, saline playas which developed in the Mojave Desert during the Holocene are a likely source of much of the carbonates and soluble salts that are accumulating at shallow depths both in phase 1 soils and in the formerly noncalcareous, nongypsiferous argillic horizons of phase 2 and 3 soils. 相似文献
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中国土壤系统分类中盐成土及其相关土壤诊断标准的修订建议 总被引：1，自引：1，他引：0
对土壤进行科学分类是土壤资源开发和利用的基础,也是土壤调查制图的基础,在农业生产、土地利用的决策和管理中发挥着重要作用,标志着土壤科学的发展水平.目前国际上土壤分类主要有《美国土壤系统分类》(以下简称《ST》)[1]和《世界土壤资源参比基础》(以下简称《WRB》)[2],我国从1984年开始的中国土壤系统分类研究,也已形成了具有中国特色的《中国土壤系统分类》(以下简称《CST》)[3]成果.这三个分类体系都是以定量化的诊断层和诊断特性为基础的多阶层土壤分类体系. 相似文献
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选取湖南省东部地区12个由第四纪红色黏土发育的典型土壤剖面,在对其成土环境、剖面形态特征及其理化性质进行研究的基础上,按照中国土壤系统分类方案,检索出了其诊断层和诊断特性,据此确定了其在中国土壤系统分类中的归属。结果表明,供试土壤剖面包含了淡薄表层、暗瘠表层、低活性富铁层、黏化层、聚铁网纹层等10个诊断层和诊断特性,其在中国系统分类体系中的位置分别为：淋溶土、富铁土和雏形土3个土纲;湿润淋溶土、湿润富铁土和湿润雏形土3个亚纲;简育湿润富铁土、铝质湿润淋溶土和铝质湿润雏形土3个土类;暗红简育湿润富铁土、表蚀简育湿润富铁土、网纹简育湿润富铁土等6个亚类;按照土族和土系划分标准,建立了黏质高岭石型酸性热性-普通铝质湿润淋溶土等9个土族和燕塘系(43-LY01)等12个土系。研究发现：受亚热带气候影响,许多土壤剖面发生了富铁铝化过程,且由于淋溶强烈,孔隙周围形成了聚铁网纹层,而现行的《中国土壤系统分类检索（第三版）》还不能给出一个合适的位置,因此建议在铝质湿润淋溶土亚类中增设一个可以反映相关特性的网纹铝质湿润淋溶土亚类。 相似文献
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《Geoderma》2001,99(1-2):1-25
Interest in site-specific agronomic management in intensively cropped regions necessitates characterization of subsurface water movement for efficient water management (irrigation timing) and control of off-site agrichemical movement. Soils formed in fluvial sediments in portions of the Upper Coastal Plain of Georgia (USA) are extensively used for peanut, cotton, and corn production. Certain proximate soils in this region possess contrasting subsoil properties, and it was hypothesized that these differences would have major effects on water redistribution across the landscape. This could be important in irrigation management, where soils possessing increased impedance to vertical flow could require decreased irrigation as opposed to soils without vertical flow restrictions. At a site near Plains, GA. (USA), hydraulic properties of soils with differences in overlying sand thickness and contrasting argillic horizon textures (sandy vs. loamy) were evaluated. The soils were predominantly in loamy and sandy families of Typic, Arenic, and Grossarenic Kandiudults. Laboratory measurements, field monitoring of matric potentials under simulated and natural rainfall, and modeling (VS2DT) were utilized to evaluate soil hydraulic properties. Reduction in vertical Ks occurred in horizons containing higher clay (argillic horizon). Changes in tension and build ups in hydraulic gradients associated with infiltration and redistribution events existed above and within horizons with low Ks. Evidence suggested there was less groundwater recharge occurring in the loamy than in the sandy pedons, suggesting more pronounced lateral flow occurred in the loamier soils. Model simulations of water movement across a slightly sloping (1%) simulated landscape indicated lateral gradients of flow existed within the solum of these soils. Analyses of tracer (Br) movement suggested a very slight lateral redistribution occurred within a relatively short monitoring period within the sandy pedon's Bt1 horizon, and the Bt2 and Bt3 horizons of the loamy pedon. Evidence suggested both loamy and sandy argillic horizons slightly, but not overwhelmingly, induced lateral flow on these landscapes. 相似文献
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Strongly weathered red and yellow soils with thick (490–900 mm) humic Al horizons (Haplohumox and Palchumults) derived from sandstones and basic igneous rocks, and occurring near the east coast of Southern Africa, are described and discussed in terms of their distribution, morphology, texture, mineralogy, chemistry, genesis and classification. The high organic matter content (2–5%C) of the Al contributes significantly to a high pH-dependent negative charge, probably to poorer crystallinity of goethite and kaolinite and to the transformation of haematite to goethite. Varying proportions of kaolinite and gibbsite reflect different soil ages within these old landscapes. The yellow colour of aluminous goethite, the main pedogenic iron oxide, is masked in the Al by organic matter and in red B2 horizons by haematite. Temperature may have influenced the broad pattern of occurrence of red and yellow B2 horizons. These soils need not, as previously suggested, have developed from the weathering products of an ancient laterite. Neither Soil Taxonomy nor the South African soil classification system accommodates the soils entirely satisfactorily and possible improvements to the latter are discussed. 相似文献
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Oxisols cover ≈ 23% of the land surface in the tropics and are utilized extensively for agricultural purposes in the tropical countries. Under the variable input types of agricultural systems practiced locally, some of these soils still appear to have problems in terms of proper soil classification and subsequently hinder attempts to implement sustainable agro‐management protocols. The definition for Oxisols in Soil Survey Staff (1999) indicates that additional input is still required to refine the definition in order to resolve some of the outstanding classification problems. Therefore, the objective of this study is to examine the properties of some Oxisols and closely related soils in order to evaluate the classification of these soils. Soils from Brazil, several countries in Africa, and Malaysia were used in this study. Field observations provided the first indication that some of the presently classified kandi‐Alfisols and kandi‐Ultisols were closer to Oxisols in terms of their properties. Water‐retention differences and apparent CEC of the subsurface horizons also supported this idea. The types of extractable Fe oxides and external specific surface areas of the clay fractions showed that many kandic horizons have surface properties that are similar to the oxic horizons. Micromorphology indicated that the genetic transition from the argillic to the oxic involves a diminishing expression of the argillic. Properties, such as CEC, become dominant. The kandic horizon is therefore inferred as a transition to the oxic horizon. It is proposed that the Oxisols be keyed out based only on the presence of an oxic horizon and an iso–soil temperature regime. The presence of a kandic horizon will be reflected at lower levels in Oxisols. The Oxisols will now be exclusive to the intertropical belt with an iso–soil temperature regime. The geographic extend of the Oxisols would increase and that of kandi‐Alfisols and Ultisols would decrease. A few kandi‐Alfisols and Ultisols in the intertropical area will have low CEC which would fail the weatherable mineral contents. The kandic subgroups of some Alfisols and Ultisols will be transitional between the low (< 16 cmolc [kg clay]–1)‐ and high (> 24 cmolc [kg clay]–1)‐activity clay soils. The proposed changes to classification will contribute to a better differentiation of the landscape units in the field. Testing of the proposed classification on some Malaysian soils showed that the new definition for Oxisols provides a better basis for the classification of the local soils and the development of meaningful soil‐management groups for plantations. 相似文献
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中国人为土的多样性 总被引：3，自引：0，他引：3
Human activities make strong effects on soil formation. Anthropogenic soils are much more intensive and extensive in China for their history of agricultural production can be dated back to more than 7 000 years ago. Owing to different physical conditions and land uses, the anthropogenic soil-forming processes are various. Anthrosols are proposed, and the corresponding soil order is set up in Chinese Soil Taxonomy (CST). Mainly based on 6 Anthropogenic diagnostic horizons, which are anthraquic epipedon, hydragric horizon, irragric epipedon, cumulic epipedon, fimic epipedon and agric horizon, the Anthrosols Order is subdivided into 2 soil suborders and 4 soil groups. Meanwhile the classification of Anthrosols in CST has been basically accepted as the classification of Anthrosols in World Reference Base for Soil Resources (WRB). 相似文献
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《CATENA》2004,57(2):157-174
Parent materials greatly influence soil development and the distribution of soils on the southeastern US Coastal Plain. We examined the physical, chemical, and mineralogical properties of 11 pedons in a 1-ha plot on the Upper Coastal Plain of Georgia, USA. Uniformity of parent materials was assessed by sand grain size characteristics. The soils have sandy epipedons of variable thickness and argillic horizons of variable texture. Six of the pedons also have kandic horizons. They are classified (US Soil Taxonomy) in Psammentic, Grossarenic, Arenic, and Typic subgroups of Paleudults and Kandiudults. Loamy pedons possess argillic horizons with two distinct increases in clay and greater differences between eluvial and illuvial horizons than sandy pedons. The upper boundary of the argillic horizon is approximately parallel to the present geomorphic surface, suggesting that it is associated with the contemporary surface. Discontinuities, identified by changes in sand grain size ratios and plots of the third (skewness) and fourth (kurtosis) moments of sand grain distribution, roughly correspond to the bottom of the solum. Our data suggest that there are both eolian and fluvial components in the solum, whereas subjacent horizons are completely derived from fluvial deposits. Sandier pedons have greater gibbsite/kaolinite ratios, possibly because greater permeability has enhanced leaching and Si loss. Our data suggest parent materials largely control soil distribution over this plot. 相似文献
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土系划分方法研究——以江苏省新沂样区为例 总被引：1，自引：0，他引：1
作为土壤系统分类的基层分类单元,土系的划分必须经过实地调查,重视控制层段和特征土层的设立,并选择合适的分异特性作为分类指标。本文选择样区内不同景观单元中的10个土壤剖面,根据中国土壤系统分类的要求,探讨了样区内土壤诊断层、诊断特性及其在中国土壤系统分类中的归属;并在有关土系认识的基础上,探讨了土系划分的原则、依据和具体划分方法,确立了研究区土壤所具有的特征土层,依据①特征土层的种类、排列、厚度,②土壤质地和③土壤有机质含量这三类指标,把样区土壤划分为10个土系。 相似文献
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