A NEW KIND OF GRINDING AND POLISHING PLATE FOR THE PREPARATION OF THIN SECTIONS

The construction, by disc casting of epoxy resin/carborundum grinding and polishing plates is described. Such plates are slow wearing and can be produced in the labouratory to a wide range of specifications.     

THE IMPREGNATION OF WET PEAT FOR THE PRODUCTION OF THIN SECTIONS

A technique is described to replace the water in peat by acetone prior to impregnation with resin. The peat is exposed to the vapour of aqueous acetone of increasing concentration up to 100 per cent acetone. After impregnation with resin, high quality thin sections can be obtained.     

THE PREPARATION OF CLAY SOILS FOR DETERMINATION OF STRUCTURE

Most methods for the determination of structure require the soil to be freed of water and yet to retain its original character. The methods of freeze-drying and critical point-drying are examined and it is concluded that they are not generally satisfactory. It is possible to preserve the soil fabric whilst water is slowly exchanged with an organic solvent (e.g. methanol or dioxan). The fabric is hardened and the degree of hardening is increased by subsequent exchange with certain water-immiscible solvents (e.g. diethyl ether). Some shrinkage must be tolerated when it is desired to remove the liquid from the fabric. The best method was found to be infiltration by liquid carbon dioxide and its removal above its critical temperature. Despite some shrinkage the fabric seems unchanged.     

A TECHNIQUE FOR SELECTIVE SOLUTION OF IRON OXIDES IN THIN SECTIONS OF SOIL

A technique to study optically the effects of three different extraction procedures for removing iron from thin sections of soil is described. The distribution of iron in each section is recorded before treatment. Silicone grease is then applied to all parts of the sections except those to be treated. The areas selected for treatment are immersed for 24 hours in one of three beakers containing dithionite-citrate-bicarbonate, 02M ammonium oxalate at pH₃ and 01M K-pyrophosphate at pH10. After treatment, the sections are degreased and the effects of the various treatments examined optically.     

A METHOD FOR THE QUANTITATIVE MEASUREMENT OF ANISOTROPIC PLASMA IN SOIL THIN SECTIONS

A method is described to measure the total amount of anisotropic plasma visible in soil thin sections. The proportion occurring within 15μm of void and skeletal grain surfaces is also measured. The results can be presented as an orientation index.     

THE MEASUREMENT AND CHARACTERISATION OF VOIDS IN SOIL THIN SECTIONS BY IMAGE ANALYSIS. PART II. APPLICATIONS

Image analysis was used to measure and characterise the voids in two sets of soil samples; (i) a surface water gley soil of the Deighton series and (ii) soils from a compaction experiment. The results show that the Deighton soil contains two impervious horizons separated by a much more porous horizon. In all the horizons most of the pore space is due to pores >180μm diam. In the case of the soils from the compaction experiment compaction was shown to change the shape, orientation and size distribution of the pores considerably. The range of measurements demonstrates that image analysis is applicable to several areas of soil research.     

THE MEASUREMENT AND CHARACTERISATION OF VOIDS IN SOIL THIN SECTIONS BY IMAGE ANALYSIS. PART I. PRINCIPLES AND TECHNIQUES

The introduction of the image analysing computer (Quantimet 720) makes possible the rapid and accurate measurement of components in thin sections and extends the range of measurements possible. Two techniques for presenting material for analysis are outlined. Models are used to demonstrate the measurement of size, irregularity and orientation of components and their discrimination according to shape.     

不同类型菜田和农田土壤磷素状况研究

以西北地区有代表性的灌淤土为供试土壤,研究不同类型菜田(露地菜田和蔬菜保护地)及农田土壤的P素状况,以及蔬菜保护地土壤P素的空间分布特性。结果表明,露地菜田、蔬菜保护地土壤全P、无机P、有机P、Olsen-P的平均含量是一般农田土壤的1.43~8.30倍,土壤Olsen-P占全P的比率显著高于一般农田。蔬菜保护地土壤各形态P素主要积累在0~30cm土层,并随土层深度的增加各形态P素的含量逐渐降低,各土层Olsen-P、Ca2-P、Ca8-P、Al-P含量降低幅度明显高于Fe-P、O-P、Ca10-P。     

SOILS OF THE STATE OF BAHRAIN

The State of Bahrain lies in the arid zone on the southern side of the Arabian Gulf. The factors influencing soil formation on the Islands are examined and an account given of the soils. These can be placed in four groups: Solonchaks, Regosols, Yermosols and Fluvisols. The Solonchaks of the northern plain contain unprecedented amounts of gypsum which, in the absence of leaching, give rise to a variety of morphological features. The distribution of Regosols, Yermosols and Fluvisols can be related closely to physiographical location throughout the country.     

九华山之土壤

本文在阐明九华山土壤形成条件的基础上,着重阐明了各土类的特性和土壤的垂直分布规律。九华山的基带土壤为红壤,自下而上依次分布着红壤、山地黄棕壤、山地酸性棕壤和山地灌丛草甸土。     

THE ALKALINITY OF ALKALI SOILS

The theoretically derived equation: log Alk–pH = log Pco₂–7.82 describes the relation between three easily estimated parameters, viz. the composition (alkalinity), CO, partial pressure and the pH of the soil solution. This equation is also important for understanding the formation of alkaline soils. The concept of residual alkalinity, i.e. the difference between the alkalinity and the total concentration of the divalent cations in the soil solution (on an equivalent basis) is introduced. In a closed basin with excess evaporation over precipitation highly alkaline soils, i.e. soils with a pH above 8 to 8.5, develop if the inflowing water has a positive residual alkalinity. A number of processes, such as weathering, oxidation and reduction, cation exchange, precipitation, addition of neutral salts, evaporation, which may influence the alkalinity and residual alkalinity of natural waters and soils are discussed briefly.     

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.     

ALPINE SOILS OF NORTH-EAST SCOTLAND

Many features of the alpine soils of NE. Scotland are related to altitude. The deep contemporary humose A horizon has formed in Post-Boreal to recent times. Its formation was preceded by a phase of profile development characterized by very scanty A horizon development. This phase was interrupted by a stage of frost disturbance, probably equated with the Highland Re-advance. The earliest part of the pedogenetic cycle is represented only by cryogenic redistribution of the fine fraction, within the parent material column, which occurred between 12,000 and 28,000 B.P.     

栗钙土的年龄

在阐明粟钙土发生特性的基础上,本文运用放射性碳方法断定了玄武岩熔岩台地上栗钙土有机质和腐殖质组成中胡敏酸、胡敏素的年龄.结果表明,我国栗钙土与其它国家的软土系同一时期的产物,它们形成于大约6000年以前.栗钙土有机质诸部分的年龄序列是:胡敏酸>胡敏素>土壤有机质.     

衡山土壤之研究

在阐述衡山土壤形成条件的基础上，重点阐明了衡山各类土壤的性质特征和土壤垂直分布规律、并根据诊断土层和诊断特性，对其进行系统分类。衡山土壤分布自下至上依次为湿润富铁土、黄色湿润富铁土、常湿富铁土和常湿淋溶土。在各山峰顶部和陡坡处，分布有酸性常湿雏形土。