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1.
D. McGARRY 《European Journal of Soil Science》1989,40(1):199-207
Changes in soil structure and fabric of a Vertisol in northern New South Wales, Australia following pre-sowing cultivation at two different soil water profiles (dry and wet) were investigated. Both the dry and wet cultivated plots had similar, intensive pre-sowing cultivation typical of commercial practice for irrigated cotton. For thin section analysis two profiles were sampled prior to this cultivation, and three from each of the dry and wet plots were sampled after cultivation. Samples were also available from soils in the area which had never been cultivated. All soils had porphyric fabric with vo-ma-skel-insepic plasmic fabrics and a wide range of pedological features. The cultivated soils had other pedological features not present in the 'never'-cultivated soils, i.e. zones within which the plasma exhibited a moderately- to strongly-striated orientation pattern. The more strongly-striated units included occasional, very fine to fine joint planes. These zones were domi-nantly equant to planar with sharp boundaries. Internally, they consisted of layer silicate plasma and mineral skeleton grains most commonly similar to the enclosing material. The proportion of these features differed between treatments especially in the 0.05-0.25 m layer. Soil cultivated dry, and land prior to cultivation had < 1 % of their area composed of zones of striated clay, compared to up to 17% in the wet cultivated soil. This may be related to a greater incidence of shearing of soil in a plastic state by tillage implements and tractor wheels. In the dry cultivated soil shear appears to be of minimal significance. 相似文献
2.
A. BRUAND 《European Journal of Soil Science》1990,41(3):491-497
The water-retention properties of clayey soils have been studied at ?0.3 × 105 and ?15 × 105 Pa matric potentials using three sets of clayey horizons differing in their pedological origin. Measurements were made on small clods collected in winter when swelling is at a maximum. The results are discussed in relation to variations in the clay content and clay fabric. The bulk volume, which appears to be closely related to both clay content and clay fabric, allows the variations in water retained to be explained better than with clay content alone. With clayey horizons originating from a single soil family, differences in water retained can be explained by variations in clay content alone because clay fabric does not change greatly. These results demonstrate the significance of pedological stratification in estimating the water-retention properties when a single soil characteristic, such as clay content, is used. 相似文献
3.
Micromorphological data were collected from a known layered situation in south western Australia in an effort to determine whether pedological features and soil fabrics could provide a basis for identifying the presence of rock- and soil-stratigraphic units in whole soil profiles. The use of depth functions as a basic micromorphological research technique is evaluated with regard to the recognition of sedimentary characteristics in soils and the identification of strarigraphic discontinuities. Results of this study suggest that multiple peaks in frequency-distribution patterns of pedological features are indicative of polygenesis because each peak correlates with a surface (contemporary) or buried (relic) soil profile. The analysis of soil fabric assemblages appears to provide an additional basis for differentiating soil materials. The recognition of inherited soil features facilitates tracing the provenance of soil parent materials. 相似文献
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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. 相似文献
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7.
半干旱平原地区土壤详测研究Ⅱ.土壤的发生、特性与土壤基层分类 总被引：1，自引：0，他引：1
土壤基层分类是土壤发生分类系统中的基本单元,它是构成整个土壤发生分类系统的重要组成部分,不可强予机械割裂。不过由于工作范围的大小,工作精度的差别,研究时可分别有所侧重。如在人民公社(或生产大队)土壤详测中,与小比例尺土壤调查研究中即有所不同。大地区土壤研究,着重于了解土壤的地带性演化规律,对比土壤性态上重大的差异,主要研究土类、亚类特性。但人民公社的土壤差异,是在小地区内发生的,应着重了解土壤性态上的微小差异,更多研究土类、亚类以下,土壤基层分类单元的划分。而这些土壤性态变异情况,经常可以具体作为因地制宜安排生产的指标。我国土壤变化比较繁复,各不同地带中,土壤基层单元的划分指标并不尽同,如果能把不同土区的基层分类单元有明确的划分指标,将可细致地研究土壤发生分类;而且也可使土壤研究成果,更好地与农业生产情况结合起来。为此,我们在河北怀来西八里人民公社经堂房生产大队进行土壤群测时,也着重研究了土壤发生、特性与土壤基层分类周题,用以反映半干早平原地区土壤的变化情况。 相似文献
8.
Four loess-derived soil profiles (southwest of Hannover, Federal Republic of Germany) with increasing influence of impeded water (Hapludalf to Humaquept) have been investigated micromorphologically. The nature of the different micromorphological features, as well as their distribution within the horizons of the profiles are described and quantitatively represented. Observations on the soil fabric in B-horizons show that tubular macropores have been filled either by clay skins, pure silt grains and/or clay-rich silty material. The breakdown of macropores and/or iron/manganese-enrichment may cause the occurrence of involved systems of “generations” of macropores, whose development cannot be reconstructed exactly. Semi-quantitative investigations indicate that numbers of these latter features decrease in going from well-drained soils to wetter soils. 相似文献
9.
Investigations on porosity and pedological features were carried out on thin sections of samples of a clay soil treated with a ferric conditioner. The effect of wetting-drying cycles was considered and also surface shrinkage was determined. Micromorphometric determinations of porosity, pore size distribution and number of pores per mm2 were carried out by a Leitz-Classimat apparatus. Pore shape and pedological features of ferric compounds were analysed by the point-count method. Surface shrinkage data show great differences between treated and control samples at the first wetting-drying cycle but similar values at the end of the experiment. The statistical processing of micromorphometric data shows significant differences between the control and treated soil material. Wetting-drying cycles influence the number of pores and porosity mainly in the treated soil samples. The pore size distribution is more homogeneously represented in all size classes within treated samples. Also the statistical processing of data of pore shapes and pedological features shows significant differences between control and treated soil samples. Only planar pores are not influenced by the treatment. The wetting-drying cycles affect neither the pore shape, except for planar pores, nor the different pedological features. 相似文献
10.
湖南省几种稻田土壤微生物区系的研究 总被引：2，自引：1，他引：2
对湖南省3个国家水稻工程基地的7种水稻土微生物区系的分析结果表明,7种水稻土中3类微生物总数依次为黄沙泥>紫沙泥>河沙泥>紫泥田>红黄泥>潮沙泥>黄泥田,特殊生理群的微生物数量也以河沙泥和紫沙泥等通气性好、质地好的土壤中最多,而黄泥田和红黄泥等紧实土壤中微生物数量较少。农业生产中要因土壤类型采取相应的农业技术措施。 相似文献
11.
DCD 在不同质地土壤上的硝化抑制效果和剂量效应研究 总被引：5，自引：0，他引：5
通过硝化抑制剂抑制土壤硝化作用是实现作物铵硝混合营养和提高氮肥利用率的重要途径之一。本试验采用室内模拟的方法, 在人工气候室(25 ℃)黑暗培养条件下, 应用新疆石灰性土壤研究了不同剂量的双氰胺(dicyandiamide, DCD)在砂土、壤土、黏土3 种不同质地土壤中对土壤硝态氮、铵态氮转化的影响及DCD 的剂量效应和硝化抑制效果。处理30 d 内, 各剂量DCD 处理对砂土的硝化抑制率为96.5%~99.4%(平均值为98.3%), 在黏土上为66.9%~85.6%(平均值为77.6%), 在壤土上为49.3%~79.4%(平均值为67.7%), 总体硝化抑制率表现为砂土>黏土>壤土。在砂土上DCD 的剂量效应不明显, DCD 用量从纯氮的1.0%增加到7.0%时, 土壤中硝态氮含量仅增加1.9~10.7 mg·kg-1(培养30 d 时); 而在壤土和黏土中, 土壤硝态氮含量随DCD 浓度的增加而显著下降, 存在明显剂量效应。这说明施用DCD 可显著抑制新疆石灰性土壤的硝化作用过程, 在砂土、壤土、黏土中DCD 的最佳浓度分别为纯氮用量的6.0%、7.0%和7.0%, 并在培养30 d 内发挥显著作用。 相似文献
12.
The relation between iron oxide properties and soil morphology was tested in a catena comprised by a sequence of Anionic Acrudox, Plinthic Acrudox, Plinthic Acraquox and Typic Acraquox soils, for prediction of drainage classes and moisture regimes, in the savanna region of Central Brazil. Morphological features, as mottles, nodules and low chromas of soil matrix, with iron content increasing in the sequence matrix → mottles → nodules, are evidence of iron segregation. The polygenetic nature of these soils is interpreted from the gibbsitic-kaolinitic mineralogical composition associated to high Al goethites attributed to a former dessilication weathering stage, and low Al goethites related to a presently wetter moisture regime. The soil morphological features, the iron distribution, and iron oxide properties are products of the selective dissolution of hematite inducing a xanthization process at the upper sites, followed by dissolution of “primary” high Al-goethite and formation of “secondary” low Al-goethite in mottles and nodules at the lower sites. Iron oxide properties are useful to distinguish preteric from present features in pedoenvironments, supporting the use of morphological soil properties to predict drainage classes and estimate soil moisture regimes in low intensity pedological surveys of these regions. 相似文献
13.
A general method for the non-destructive separation of discrete pedogenic features that is suitable for use with a wide range of soil types is presented. Controlled slaking of soil peds is used to achieve separation between structurally coherent features and less organized matrix material. A slaking, stabilization and sieving sequence is repeated a number of times until the matrix material has been removed. The advantages and limitations of the method are outlined and a number of applications illustrated. 相似文献
14.
The distribution of red and black soil (Xeralfs–Xerolls) associations in the Monarto area (South Australia) is complex and their genesis either being derived from a uniform parent material or a lithologic discontinuity is not known. The objectives of this study were (i) to assess Zr- and Ti-bearing grains as minerals resistant to chemical weathering prior to employing Zr and Ti in determining parent material uniformity, and (ii) to confirm whether pedological processes or a lithologic discontinuity may be responsible for the textural contrast within the red and black soil profiles. Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) were used to study chemical weathering and elemental composition of surfaces of Zr- and Ti-bearing grains. X-ray fluorescence (XRF) analysis was used to determine elemental concentrations in various soil fractions. Results showed that Zr-bearing grains consisted of only zircon having smooth clean surfaces, which are characteristic of a mineral resistant to chemical weathering. EDAX spectra confirmed that Zr was a specific element to represent zircon, suggesting its reliability to be used in assessing parent material uniformity. On the other hand, Ti derived not only from minerals (rutile/anatase) resistant but also from minerals (ilmenite/pseudorutile, biotite) susceptible to chemical weathering. This limited the usefulness of Ti as an index mineral for soil development studies. Except for Zr:Ti ratio, all other indicators of parent material uniformity, i.e., depth distribution curves of Zr and Y in various fractions and Y:Zr ratio showed no considerable inflection and variation with depth in a Xeralf (red soil). This indicated the Xeralf derived from a uniform parent material (mica schists), thereby texture contrast within a profile is due to pedological processes. On the other hand, depth distribution curves showed clear inflection and variation in Xerolls (black soils), indicating soils developed from lithologic discontinuities, so different trends in particle size fractions between 0–48 cm for MA5 and 0–59 cm for MA3 profiles compared to the underlying layers are due to parent material differences and not pedogenesis. The presence of complex red and black soil association in the landscape is attributed to the difference in parent materials, where the red soil developed from mica schist and the black soils from calcareous deposits. 相似文献
15.
The analysis of the microfabric of soils developing from calcareous argillites (with sandstone interlayers) and their derivatives
revealed the mechanisms of the transformation of the initial lithogenic features into pedogenic features. They include the
release of primary carbonates and their segregation in secondary forms, the redistribution of iron oxides, and changes in
the shape of the rock fragments and in the optical properties of the fine material in the lithomarge zone. The subsoil—the
metamorphic BM horizon—is characterized by a high content of clay composed of chlorite-vermiculite and mica-smectite minerals
along with kaolinite. The BM horizon is compact and has a massive microstructure with clay pseudomorphs over skeleton grains
and with nonsegregational forms of iron oxide pedofeatures. The diagnostic properties of this horizon are clearly revealed
in the soils on both hard rocks and loose colluvium deposits; in the latter case, they are supplemented with a stagnic marble-like
pattern. The integrity of these features corresponds to the elementary pedogenic process of the metamorphism of the mineral
mass in humid subtropics. In terms of micromorphology, this is a good example of pedoplasmation. The features testifying to
the contribution of biota in the topsoils are few; dark compact nodules are common there. Zheltozems developed from hard rocks
may be correlated with Cambisols in the WRB system; zheltozems developed from clayey colluvium display the features of clay
illuviation; together with some physicochemical characteristics of these soils, they allow us to qualify such soils as Acrisols.
There are also eluvial-gley variants of zheltozems with stagnic features. 相似文献
16.
Av horizons found in desert pavement environments are known to evolve pedogenically over geologic time. This study was conducted to determine whether increased pedogenic development of the Av (vesicular) horizon over relative time impacts the hydraulic properties of individual soil peds and the mechanism of infiltration as inferred by dye patterns. We examined peds from the Av horizons associated with desert pavements that mantled three different alluvial deposits with different relative surface ages (Qf5 (∼ 10 ka), Qf3 (∼ 50–100 ka), and Qf2 (∼ 10–50 ka)) and included an additional surface (Qf6 (∼ 4 ka)) for the dye studies. We hypothesized that increases in the development of the Av over time would lead to a more structured soil surface with greater potential flow between soil peds and lower hydraulic conductivity of the soil peds themselves. Results showed that average Ks and α of the Qf5 peds were significantly greater than estimated for the Qf2 and Qf3 peds. Although Ks was greater for the Qf5 peds, the steady-state infiltration rate was equal for the Qf3, Qf2, and Qf5 surfaces, perhaps indicating a reduction in matrix flow through soil peds and an increase in interped flow between soil peds. 相似文献
17.
Soddy-podzolic soils developed on different loamy parent materials possess several common fabric features which can be regarded as characteristic of this soil type. These features are: poor aggregation, considerable amounts of coarse plant residues in different (mainly weak and medium) stages of decomposition, predominance of brown-coloured peptized humus mainly bound up with sesquioxides, abundant clayey and silty illuviation cutans appearing in the A2 or A2 horizons where they show the strongest disruption and incorporation into the s-matrix, and different forms of biological segregations of iron and manganese hydroxides. Some differences in fabric of these soils are connected with mineralogical and physical properties of parent material. 相似文献
18.
江苏省的地质地貌与林业土壤的关系 总被引：1，自引：0，他引：1
在大范围内地质地貌对生物、气候、土壤的影响,例如高山地区的垂直分布规律,已有许多文献论述过.在小范围內地质地貌对山区林业土壤的直接影响,也在一些著作中有所反映(佐伯秀章,1959;Wilde,1958).本文只是试图就江苏省的一些具体事例,来讨论地质地貌对低山丘陵地区土壤类型、性状、分布规律及林木生长的影响.江苏省的低山丘陵,主要分布在东北部和西南部,占全省面积不到15%. 相似文献
19.
A detailed macro- and micro-morphological study of seven closely-adjacent soil profiles on calcareous clay tills in a long-established beech wood in central Denmark, shows that depth of decalcification, thickness of textural B horizon, development of umbric epipedons and development of albic sub-horizons are all related to slope inclination, slope form and to relative situation in the slope complex.The soils may be classified within four subgroups of Alfisols, while one is a Mollisol. The MAST of 8°C poses problems of typification at suborder level between frigid and mesic classes.Development of clay skins and of glaebules and concretions as indicators of the redeposition of mobilised components, are present to greater extent in stable slope situations; with least lateral subsoil water movement. Development of albic horizons is related to greater lateral water movement.Development of cutanic features by argilluviation - argillans - do not exclude features formed by redeposition of carbonates - calcitans. Soil plasmic fabrics with both features are termed calcisepic fabrics and prove deposition of clay and carbonates in the same soil horizons, usually the lower B and C(g) horizons.Morphologically the dark epipedons show intense humification and many fecal pellets because of the undisturbed and high plant productivity and intense biotic activity. The micromorphology is one of isotic argillasepic plasmic fabrics. The argillic horizons are dominantly insepic or vosepic, while the calcareous C horizons are either argillasepic, or calci-vosepic or calcisepic. It is possible that some of the carbonate reprecipitation post-dates the argilluviation, the carbonates derived during secondary dissolution in the suprajacent horizons. 相似文献
20.
A continuum approach to soil classification by modified fuzzy k-means with extragrades 总被引：6，自引：0，他引：6
The need for a more continuous approach to soil classification is discussed, and methods based on the mathematical constructs known as fuzzy sets are considered most appropriate for this. A centroidal grouping method, fuzzy k-means with extragrades, which quantifies the intragrading and extragrading of soil individuals is described. An example of the application of this technique to an area of 4800 ha at Wesepe in The Netherlands is presented. The results show that the technique could create a classification that reflects the main pedological features of the area in a continuous way. Although there may be problems in selecting the optimal number of groups and degree of fuzziness, we conclude that the method is most promising and worthy of consideration when any type of quantitative soil classification is required. 相似文献