EDAPHOIDS AND PALEOSOLS OF BASALTIC ORIGIN IN THE GALILEE, ISRAEL

Red soil-like layers intercalated amid basaltic flows from the Miocene-Pleistocene in the Galilee, Israel, were examined. Micromorphological features which can be related to (a) translocation of materials, and (b) biological activity, and are therefore of distinct pedological origin, identify two of the layers as paleosols. Absence of these features and preservation of the fabric of the parent basalt serve to identify the third layer as an edaphoid. A fourth layer consists of an edaphoid superimposed on a paleosol. The edaphoids are composed almost entirely of a dioctahedral smectite. In two of the paleosols dioctahedral smectites predominate. In the third kaolinite and haematite are present also in considerable amounts. The presence of quartz in the paleosols is attributed partly to precipitation from Si-rich solutions percolating the upper basalt layer and partly to aeolian contamination. In all the layers the free iron is predominantly in an anhydrous form. Similarity in the clay mineral composition of the Plio-Pleistocene paleosols with that of contemporaneous basaltic soils is taken to indicate similarity in climatic conditions of formation. Differentiation between paleosols and edaphoids cannot be made by the use of a single criterion but must be based on corroborative evidence derived from micromorphological and mineralogical examinations.     

CLAY AND SILT MINERALOGY OF SOME SOILS FROM QASIM, SAUDI ARABIA

Qasim, some 500 km north-west of Riyadh, is one of the agriculturally important areas of Saudi Arabia. Silt fractions of the soils of the Wadi ar Rimah and side wadis, classified as Torrifluvents, are characterized by high quartz contents and the universal occurrence of kaolinite and felspar, generally with plagioclase predominant; mica, chlorite and hornblende also generally occur. The clay fractions contain mainly palygorskite and a smectite-mica interstratification with smaller amounts of kaolinite, traces of quartz and occasionally chlorite. Palygorskite generally increases in content with depth. Variations in mineralogy probably reflect changes in depositional conditions rather than pedogenic processes; possible reasons for the high palygorskite content are discussed. Sedentary soils (Torriorthents) reflect the mineralogy of the rock from which they were derived. In clay fractions from salt-marsh soils (Salorthids) calcite reacts strongly with smectite-mica during DTA.     

小兴安岭山地暗棕色森林土粘土矿物学特性

本文研究了温凉湿润地区不同地形条件下花岗岩母质上的山地暗棕色森林土土壤链的矿物风化.结果表明,由阳坡岗顶、中部到阴坡下部,酸性淋溶由强变弱.原生铝硅酸盐矿物蚀变为次生的粘土矿物:黑云母酸-弱酸性→二八面体Al(层间)蛭石弱酸-中性→Al绿泥石;微斜长石→蒙皂石;斜长石弱酸性→高岭石或蒙皂石一高岭石类矿物的混层物.在针阔混交林作用下,A层腐殖酸与铝、铁络合,铝蛭石化过程弱.AB和B层黑云母和长石蚀变强,矿物晶层间羟基铝积累,阳坡岗顶Al(层间)蛭石和蒙皂石化,形成了较高的土壤潜在酸度;阴坡下部除Al蛭石外,并有成土Al绿泥石形成,潜在酸度低.含有蒙皂石的C层,层间铝有积累.矿物蚀变和晶层Al转移,是山地暗棕色森林土酸度的主要来源.红松林类型和林木生长情况与土壤粘土矿物学特性及其化学环境条件密切有关.     

CLAY MINERALOGY OF SOME SEASONALLY FLOODED SOILS OF EAST PAKISTAN

The clay fractions of four seasonally flooded soils from East Pakistan have been studied using X-ray, DTA, and infra-red methods, total chemical analysis, surface area determination, and electron microscopy. The soils represent young alluvium (Borda), a juvenile groundwater laterite (Nunni), a groundwater lateritelatosol intergrade (Noadda), and a surface-water glei (Chhiata). Mica and kaolinite were present in all the soils, and vermiculite in all except possibly Noadda. Vermiculite, total magnesium content, and SiO₂/Al₂O₃ ratio decreased and kaolinite increased in the sequence Borda–Nunni–Noadda. Electron micrographs indicated that in the Borda soil, which is the youngest and subjected to the longest period of annual flooding, iron hydroxides are present as gels coating the surfaces of the clay mineral particles. Such coatings are less apparent in the Nunni clay, and in the Noadda clay most of the ‘free iron oxides’ appear as small granules. The Chhiata soil has about 12.5 per cent of its clay fraction in the form of an amorphous gel rich in silica, and much of the mica and vermiculite in a randomly interstratified complex.     

CONCENTRATIONS AND ACTIVITIES OF IONS IN SOLUTIONS DISPLACED FROM BASALTIC SOILS

Soil solutions displaced from Antrim basaltic soils were analysed for major inorganic constituents. The solutions were nearly saturated with aluminium and phosphate but not sulphate. Iron concentrations were greatly in excess of ferric hydroxide solubility. The solutions were less concentrated than those described for soils of Britain and the U.S.A., representing a leaching environment.     

THE GENESIS OF SOME BASALTIC SOILS IN NEW SOUTH WALES

Field and laboratory investigations of 182 soil samples and their underlying basalts in the Inverell area indicated that not all of the red soils in the area are relicts of Tertiary laterization as was previously thought. The soils on basalt were divided morphologically and mineralogically into shallow (black, brown/ chocolate, and red) and deep (krasnozems and lateritic soils) profiles. The mineralogy of the sand fractions of the shallow soils, which were similar in all respects except colour and location, suggests that they are young soils as the heavy minerals in the sand fractions are dominantly pyroxene, olivine, and the black opaque minerals which weather quite rapidly. The shallow black and brown/chocolate soils occupy whole slopes under grassland vegetation or grassland with trees, while the shallow red soils are restricted to steeper well-drained slopes and crests where trees tended to dominate grass. In similar areas throughout the New England region red soils are found on basalt in areas receiving 75 cm or less average annual rainfall, although previous workers have assumed that red soils develop from basalt at present only in areas receiving more than 140 cm average annual rainfall. The deeper soils, which were characterized by a lower pH, occupied upper or upper and middle slopes. The dominance of the resistant altered opaque minerals in these soils suggests that they are relict soils. The krasnozems showed little horizon differentiation apart from a slight darkening of the upper 8–10 cm. The lateritic soils had marked horizons, with laterite overlying mottled and pallid zones, the whole sequence being deeper than the krasnozems. The lateritic soils contained a high percentage of heavy minerals in the sand fractions in contrast to all the shallow profiles. Only one period of laterization is indicated in the area, although the laterite levels were not always accordant.     

NON-EXCHANGEABLE AMMONIUM IN SOILS OF ISRAEL AND ITS RELATION TO CLAY AND PARENT MATERIALS

The occurrence of non-exchangeable ammonium in the main soil groups of Israel and its relation to various factors were determined in 129 samples from thirty-one profiles. In arid and semiarid soils the level ranged from 0·18-0·53 me/100 g, with most values falling between 0·25 and 0·40 me/100 g. In the sub-humid Mediterranean region the values ranged between 0·04 and 1·0 me/100 g, with most of them falling between 0·14 and 0·65 me/100 g. In most cases the percentage of non-exchangeable ammonium-N in the total soil nitrogen was in the range of 2–25 per cent. The clay fraction is a significant factor influencing the amount of non-exchangeable ammonium in the soils tested. The relatively low amounts of non-exchangeable ammonium found are consistent with the predominant clay mineral in most of the soils being montmorillonite. A good correlation was obtained with the content of illite, which is the main carrier of the non-exchangeable ammonium. The mean non-exchangeable K/non-exchangeable NH, ratio in the Israeli soil clays was 17. In soils derived from or affected by aeolian dust, the level of non-exchangeable ammonium calculated for the clay fraction spans that of aeolian dust and is, in general, higher than in soils developed from limestone, dolomite, marl, tuff, or basalt.     

用电导热散法研究可变电荷土壤粘粒与离子的相互作用

本工作选用二种可变电荷土壤粘粒(<2μ),分别含有0.35×10^-4-1.3×10^-4mol/L的不同电解质,在不同含水量下,在5—50℃范围内测量其直流电导率的变化。试验结果表明,电导热散法是研究土壤粘粒与离子相互作用的有用手段;电导率-温度曲线上的折点温度是随含水量、电解质种类和土壤类型而不同。在相同含水量下,含有不同电解质的红壤体系的折点温度具有如下的变化顺序:CaCl₂>Na₂SO₄>KCl>Ca(NO₃)₂>NaNO₃;砖红壤体系的折点温度明显高于红壤体系。折点温度的高低是土壤粘粒与离子相互作用强度的反映。     

CLAY MINERAL DISTRIBUTION AND ORIGIN IN THE SOIL TYPES OF ISRAEL

The mineralogical composition of clays (< 2μm) in representative profiles of all soil types of Israel was investigated. The soils were classified according to their clay mineral assemblages into three groups. I. Montmorillonitic soils. Montmorillonite is the dominant mineral and exceeds 65 per cent of the total minerals found; each of the other minerals comprises less than 15 per cent. 2. Montmorillonitic-kaolinitic soils. The soil clay fractions contain 50-60 per cent montmorillonite and 15-25 per cent kaolinite, generally adding up to more than 75 per cent of the clay fraction. 3. Montmorillonitic-calcitic soils. The clays contain more than 10 per cent calcite. Montmorillonite is the dominant clay mineral (except for one soil type, mountain rendzina, where calcite is dominant). The first and second assemblages are typical of the soils of the Mediterranean zone, whereas the soils of the desert zone are characterized by the third assemblage. The origin of montmorillonite, kaolinite, and illite, the three main clay minerals, was found to be detritic, as was the origin of palygorskite which was mainly found in the calcite rich soils of the desert zone. The cation exchange capacity of montmorillonite seems to be higher under higher precipitation. Montmorillonite content and cation exchange capacity of the clays were found to be highly correlated. The carbonate content of the clay fraction and the amount of carbonate in the soil were also highly correlated.     

中国土壤中粘粒矿物的分布规律

土壤粘粒部分的组成和性质在土壤发生学及土壤肥力特性的研究中都占很重要的位置。过去认为土壤粘粒中的无机物都是非晶形的,自从伦琴射线衍射应用到土壤学研究中后,大家都公认土壤粘粒部分含有晶形结构的矿物。     

A COMPARATIVE STUDY OF NITRIFICATION IN SOILS FROM ARID AND SEMI-ARID AREAS OF ISRAEL

The influence of different factors on the nitrification of an added ammonium salt and inherent soil-N in soils from arid and semi-arid areas of Israel was investigated. Nitrification of ammonium-N proceeded rapidly at 28°C but was inhibited partially or completely in soils incubated at 37·40°C. In contrast, nitrate formation from inherent soil-N proceeded better at 37·40 °C than at 28 °C. Bacteriological examination showed that a temperature of 37·40 °C had an injurious effect on the population of nitrifiers, especially the nitrate-forming bacteria. Nitrification by the Nitrosomonas-Nitrobacter group in culture media was also markedly inhibited at 37 °C as compared with that at 28 °C. Chloromycetin at a concentration of 25 mg per 100 g soil, and potassium chlorate at a concentration of 10^-3m suppressed the formation of nitrate from ammonium, but did not exert any appreciable effect upon nitrate formation from inherent soil nitrogen. Sodium sulphacetamide inhibited the production of nitrate from ammonium-N more strongly than that from inherent soil-N. Marked differences in the two nitrification processes in the soils investigated provided good evidence that the greater part of nitrate originating from soil-N is produced by some process other than that which is responsible for nitrification of ammonium-N.     

SEPARATION OF THE LIGHT FRACTION FROM SOILS BY ULTRASONIC DISPERSION IN HALOGENATED HYDROCARBONS CONTAINING A SURFACTANT

Partially humified material can be separated from other soil material by flotation on a bromoform-petroleum spirit mixture of density 2·0 g cm^-3. Maximum recovery of partially humified material requires ultrasonic dispersion and the addition of a surfactant to the suspension. For large-scale work‘Nemagon’ may be used in place of the bromoform-petroleum spirit mixture.     

浙江省三种红、紫色砂页岩发育土壤的矿物学研究

本文用Ｘ射线衍射分析,红外光谱分析、透射电镜及Ｘ射线荧光分析对浙江省三种红、紫色砂页岩发育的红砂土、紫砂土和红紫砂土的矿物进行了分析。     

广东北江第四纪沉积物发育土壤的矿物特性

本文分析了粤北武水、北江、横石水和连江各级阶地及河漫滩上各时代沉积物发育土壤的粘粒矿物和原生矿物。结果表明,不同河流流经地区不同,物质来源不同,其矿物组成有别;同一河段,形成于早更新世的三级阶地(T₃)上的土壤矿物组成与形成较晚的各级阶地差异甚大,这是母质来源和风化成土条件不同所致;二级阶地(T₂)、一级阶地(T₁)及河漫滩(T₀)上的土壤矿物相似,只是风化程度有异,随着阶地升高,形成年代愈老,富铝化程度愈强烈;但各级阶地之间差异程度不均等,T₂至T₁之间变幅大,T₁至T₀之间差异较少,这是时间因素和古气候波动性叠加所致。