bluuebunny/crossref_metadata_2025_split huggingface dataset:
WATER CONTENT AND SOIL STRENGTH
Authors: GREACEN E. L. 
Published: July 2006

SummaryThe strength of beds of soil aggregates, saturated and unsaturated, has been measured with a ring shear machine. For saturated loose soil with free drainage the cohesion and friction components and, therefore, total strength are proportional to the applied normal load. When sheared under load the soil compresses to an ultimate voids ratio after which there is negligible change. This ultimate state differs from the critical voids ratio for saturated clay in that it appears to depend on the strength of the individual aggregates as well as on the nature of the soil material.In unsaturated soil, as the aggregates are strained, suction in the pore water increases. This suction acts as an equivalent applied load on the water‐filled fraction of the soil, and increases its potential resistance to strain by an amount determined by the apparent coefficient of friction of the saturated soil. The ultimate voids ratio for the unsaturated soil at any load is higher than that for the saturated soil.
DETERMINATION OF ORGANIC CARBON IN SOIL
Authors: BREMNER J. M. , JENKINSON D. S. 
Published: July 2006

SummaryA variable, and often substantial, amount of the carbon in carbonized materials, such as coal, charcoal, and graphite, is oxidized when these materials are treated with acid dichromate under conditions used in determining soil organic carbon. It is concluded that these methods cannot be used to detect carbonized materials in soil or to discriminate between carbon in carbonized materials and carbon in soil humus.
TOTAL ELEMENTS IN TOPSOILS FROM IGNEOUS ROCKS: AN EXTENSION OF GEOCHEMISTRY1
Authors: WELLS N. 
Published: July 2006

SummaryThe amounts of eighteen elements Al, Fe, Mg, Ca, Na, K, Ti, Zr, Cr, Ni, Co, Mn, Mo, Ga, Cu, V, Sr, Ba, in topsoils from igneous rocks of the South‐West Pacific region have been related to the nature of the parent rock, the degree of soil weathering, and the organic‐matter content.When the mineral topsoils are only weakly weathered the total‐element contents are directly related to geochemistry. In strongly weathered topsoils the geochemistry of primary minerals has largely been replaced by the chemistry of secondary minerals. In combining analyses of topsoils having varying degrees of weathering within the parent‐rock groupings ultrabasic, basaltic, andesitic, and rhyolitic, the amounts of the elements are greatly modified by soil‐forming processes, but the distribution trends inherited from magmatic fractionations remain for Fe, Mg, Na, K, Ti, Cr, Ni, Co, Mn, Mo, Cu, V, Sr, Ba.The leaching or concentration of elements during soil weathering was traced from the build‐up of clay within parent‐rock groupings. Under the high rainfalls of the region soil weathering was accompanied by loss of Mg, Ca, Na, K, Sr, Ba, resulting in a concentration of Fe, Ti, Mo, Ga, V, and little, or irregular, change in Al, Zr, Cr, Ni, Co, Mn, Cu.The leaching of elements in soils derived from acidic rocks can be modified by litter from vegetation such as kauri (Agathis australis). In strongly podzolized, strongly weathered topsoils with a kauri cover the elements normally concentrated under climatic weathering have been removed by vegetative leaching, and silicon is the residual element.Organic topsoils had lower element contents (on oven‐dry weight) than the mineral‐organic soils.
COMPOSITION OF COLLOIDS IN THE SOILS OF ISRAEL
Authors: RAVIKOVITCH S. , PINES FANYA , BEN‐YAIR M. 
Published: July 2006

SummaryBy their chemical composition, the colloids from various types of soils in Israel may be grouped into three classes. According to their mineralogical composition the colloids represent various associations, two of which are conspicuous.(a) Colloids with SiO2/R2O3 ratio of 2.0–2.6. They are devoid of calcium carbonate, relatively poor in potassium and phosphorus, and content of organic matter is generally moderate. In the combination of clay minerals found, kaolin is predominant; in addition there are present illite, hematite, quartz, and, in some instances, montmorillonite. These colloids are characteristic of soils belonging to the Mediterranean red earths including terra rossas, brown Mediterranean soils, and brown‐red sandy soils‐leached soils of the humid and sub‐humid regions, formed from hard limestone, dolomite, hard chalk, and kurkar.(b) Colloids with SiO2/R2O3 ratio of 3.6–5.2. Rich in calcium carbonate, potassium, and phosphorus, relatively poor in organic matter. In the association of clay minerals, montmorillonite is predominant; in addition there are also present illite, kaolin, and quartz. In some instances attapulgite was identified in appreciable quantities. The colloids also contain considerable quantities of calcite. The soils for which these colloids are characteristic were formed from soft chalk, marl, aeolian desert dust, and are found principally in the semi‐arid and arid regions of Israel. They include rendzinas of the mountains and valleys, loess, aeolian sandy soils, and hamadas.(c) Colloids with SiO2/R2O3 ratio of 3.4–3.8. Most of them contain calcium carbonate, their potassium content is moderate, and they are relatively poor in phosphorus and organic matter. By their mineralogical composition these colloids resemble the combination in which montmorillonite is the principal clay mineral. They are characteristic of alluvial soils formed from alluvium of the Mediterranean red earths and rendzinas. The soils were developed under subhumid and semi‐arid climatic conditions.
SALINE SOILS IN THE KIRKUK PLAIN, NORTHERN IRAQ
Authors: HARRIS S. A. 
Published: July 2006

SummaryThe Kirkuk Plain has undergone partial salinization, followed by weak leaching. The areas irrigated in the past are the worst affected. Quality and quantity of irrigation water are most important factors in controlling the degree of salinization, while minor factors include deep gullies and the presence of a gypsum bed near the surface. The salts originate from the Fars Beds and the gypseous alluvium. Saline soils were encountered in areas with water tables much deeper than 2 m.
THE EFFECT OF pH ON THE WET STRENGTH OF SOIL CRUMRS
Authors: EMERSON W. W. , DETTMANN M.G 
Published: July 2006

SummaryThe clay‐clay attractive forces were greater in crumbs from acid soils than crumbs from similar soils but Containing free CaCO3. This has two causes: (a) positive charges on the edge faces of the clay crystals; (b) exchangeable trivalent cations on the clay. Using the improved sodium‐saturation method these two causes were distinguished by measuring the reduction in the strength of the crumbs by (a) raising the pH of the percolating NaCl to 7.4 with para‐nitrophenol buffer, and (b) preliminary NaCl‐HCl leaching. The effect of trivalent cations was dominant in very acid soils where Al+++ can exist in the soil solution. The soil conditioner‘Flotal’strengthens soil crumbs, initially at least, by substituting Fe+++ ions on the exchange complex. No evidence was found for cementing by precipitated Al(OH)3, or Fe(OH)3.The same concentration of CaCl2 6 × 10−3 M was required to flocculate suspensions of moderately acid surface soils both at the natural pH of the soil and after buffering the suspensions to pH 7×4. However a Callite and an acid subsoil (no organic matter) flocculated at a CaCl2, concentration of 3 × 10−4 M at pH 5. Thus there appears to be sufficient organic matter present in normal cultivated acid soils to neutralize the positive charges on the edges of any clay particles dispersed from the crumbs.It is suggested that, although liming an acid soil decreases the attractive forces between clay particles within soil crumbs, the presence of free CaCO3, in the soil helps to maintain a sufficiently high concentration of electrolyte in the soil solution to reflocculate dispersed clay and so keep drainage waters clear.
MEASUREMENT OF SOIL ANISOTROPY WITH PIEZOMETERS
Authors: TALSMA T. 
Published: July 2006

SummaryA detailed investigation of soil anisotropy on a small test area is reported. Measurements were made with piezometers of various diameters. The method employed involves two measurements of hydraulic conductivity in a single piezometer. In addition, transmission rates were determined on horizontal and vertical undisturbed core samples.The results show the vertical hydraulic conductivity to be highly variable and dependent on the depth below the soil surface. The horizontal hydraulic conductivity is less variable. Results of anisotropy calculations from piezometer measurements show a dependence on the dimensions of the cavity below the piezometer, the large piezometers gave anistropy ratios < 1, the small piezometers generally > 1.The dependence of test results on cavity dimensions is explained by the dependence of the vertical hydraulic conductivity on depth below the soil surface. Taking account of the inhomogeneous nature‐of the soil in the conventional analysis of anisotropy yields a similar dependence on cavity dimensions as was found from the field data. It is concluded that anisotropy calculations may lead to erroneous conclusions when applied to conditions in which the assumptions implicit in the theory are not approximately fulfilled.The usefulness of the methods employed in this investigation is that valuable data regarding soil variability have been obtained. This variability was not apparent in a previous study with the augerhole method.
SOIL POLLEN ANALYSIS
Authors: DIMBLEBY G. W. 
Published: July 2006

SummaryAcidic soils (pH below 5.5) may contain a great deal of pollen through the profile, and the floristic composition of this pollen may vary greatly in samples from successively greater depths.Various attempts have been made in the past to interpret pollen diagrams from soils, but they have usually broken down through the application of methods of interpretation which are only applicable to properly stratified materials such as peats or lake sediments. Once it is appreciated that downwash of pollen through the soil confers on each species a depth distribution pattern characteristic of its history on the site, broad conclusions about the vegetative history of a site can frequently be drawn.The preservation of pollen depends on the biological activity of the soil, which is closely correlated with pH. Soils which have only been decalcified recently will have a short pollen record, perhaps only a few centuries, but intrinsically base‐poor parent material may permit preservation for several millennia.
A PODZOL DEVELOPMENT SEQUENCE IN OAKWOODS AND HEATH IN CENTRAL ENGLAND
Authors: MACKNEY D. 
Published: July 2006

SummaryA sequence of soils is described from a slightly podzolized sandy brown earth to humus‐iron podzol. In this gradual degradation sequence morphological and chemical evidence is presented to suggest that the following succession of soil processes is involved:

translocation of clay;
chemical weathering of the A, horizon resulting in an association of iron with organic matter, and slight eluviation of iron: the stage of podzol intergrade;
strong iron eluviation: the stage of iron podzol;
eluviation of organic matter, which rests on or is incorporated in a previously developed iron B horizon: the stage of humus‐iron podzol. Pollen analysis has helped to establish that podzolization can occur under oak‐wood where edaphic environments favour the accumulation of thick, moist, strongly acid organic layers.
SOME SARAWAK SOILS
Authors: BECKETT P.H.T. , HOPKINSON D. 
Published: July 2006

SummaryMost of the landscape in central Borneo is sub‐mature and undergoing active degradation by creep and surface wash. The prevalent acid yellow soils, therefore, show only limited horizon differentiation. Limited areas of almost flat juvenile relief, arising from volcanic activity subsequent to the onset of the downcutting of the country rock, give rise to characteristic hydromorphic soils and vegetation.Under the extreme leaching processes operating in the moss forest zone at 4,330 ft. above sea‐level a tonalite porphyry gives rise to substantial amounts of gibbsite on weathering.
EVOLUTION OF THE TWO YOUNGEST (QUATERNARY) SOIL LAYERS IN THE SOUTH‐EASTERN PORTION OF THE AUSTRALIAN ARID ZONE
Authors: JESSUP R.W. 
Published: July 2006

SummaryThe Parakylia layer consists of a diversity of soils that formed during a former pluvial period. Representative profiles are given.The soils developed on deposits consisting of a mixture of water‐ and wind‐transported components. The period of erosion‐deposition, when the parent material layer formed, was initiated by the onset of arid climatic conditions. The climate eventually became desertic throughout practically the whole region. Calcareous wind‐borne materials, derived through deflation of soils farther to the west, were transported into the region where they were mixed with water‐transported materials of local origin. The effects of increasing aridity on erosion and deposition are discussed in relation to the evolution of certain characteristics of the parent material layer and hence of the soils. The surface gravel pavements on many of the soils developed before the soils were formed.
SOME MISCONCEPTIONS ABOUT WHAT SOIL SURVEYS CAN DO1
Authors: GIBBONS FRANK R. 
Published: July 2006

SummaryThe soil‐classification system used for a soil survey is fundamental to the success of the survey, and, if it is to be a valuable system, its nature must be determined by the purposes of the survey.The idea of a soil‐classification system which may be applied generally is valid only if the criteria required for different purposes are similar or correlate closely. Examples of surveys from Australia discredit the idea on the grounds that the soil criteria to be used in the classification differ according to the purposes of the surveys.Soil surveys based on a supposedly general‐purpose classification may thus be strictly limited in value, as they often do not make assessments of soil properties that are significant for different purposes. This is particularly so when one classification is used over a wide range of environment.Two approaches may help to make surveys more valuable. One is to devise an improved approximation to a general‐purpose classification by selecting better key criteria, and to ameliorate its deficiencies by incorporating it into an ecosystem survey. The other is to adopt a specialist classification for each different purpose of survey. Both approaches have their limitations.
RELATION BETWEEN TRACE‐ELEMENT CONCENTRATIONS IN SOIL AND PARENT MATERIAL
Authors: OERTEL A. C. 
Published: July 2006

SummaryAn examination of nineteen soil profiles from Queensland and eighteen from Central Australia, both lots formed from a variety of parent materials, and of seventeen profiles formed from dolerite in Tasmania, has shown that the relation between the concentration of a trace element in a soil and its concentration in the parent material is often not close enough for satisfactory estimation of the former from the latter. This is because pedogenic factors other than parent material also play important parts in determining the concentration in the solum. During the weathering processes the range of concentration of a trace element may be greatly increased, and at a later stage the range may be reduced almost to its original value. Although the increase may be quite general, the reduction in range appears t o occur mainly within taxonomic groups. Thus no more than a rough indication of the average concentration of a trace element in a solum can usually be obtained from its concentration in the original parent rock. There may, however, be a fairly close relation between the concentrations in the solum and the C horizon (weathered parent material) of a profile, particularly when effects produced by disturbing factors within taxonomic groups are excluded.
THE MICROSCOPY OF THE SILT FRACTION
Authors: SMITHSON F. 
Published: July 2006

SummaryThe microscopy of silt and very fine sand yields valuable information if the relevant petrological techniques are appropriately modified. The applicability of wire‐and nylon‐sieving, sedimentation, panning, heavy‐liquid separation, and staining to fine materials is considered. A method of passing through tin foil perforated with slits a few microns wide classifies material by thickness and not y real or nominal diameters, thus giving micro‐preparations with all the material near the same level of focus. The importance of dispersion when mounting and choice of correct cover‐glass thickness is discussed. A method of assessing densities of the particles in heavy liquids under the microscope is described and precautions necessary for obtaining the maximum amount of information from the examination with polarized light and phase contrast are outlined.
AN INTERPRETATION OF THE MICRO‐MINERALOGY OF CERTAIN GLAMORGAN SOILS: THE INFLUENCE OF ICE AND WIND
Authors: CRAMPTON C.U. 
Published: July 2006

SummaryThis investigation shows the complexity of soil materials which will arise in many similar areas due to the combined influence of underlying rock, local ice movement, far‐travelled ice, and wind transportation, and its elucidation has been attempted on the basis of a comprehensive knowledge of the mineralogy of the regional soils, geological strata, and superficial deposits. The criteria for recognizing the presence of wind‐blown materials (by sorting according to specific gravity) are discussed.The DyfFryn series is essentially formed on a local drift produced by ice that moved off the Coalfield and traversed the Vale of Glamorgan, this ice also influencing otherwise sedentary soils of the Sand Hall, Cogan, and Worcester series; the Ston Easton series includes soils deriving much of their content from the underlying rock, but some from the Irish Sea Drift and some blown by winds off the coastal sands; and the Gower soils and Sully phase arc influenced chiefly by the underlying rock but also by wind‐blown material. In some places the Gower series is influenced by the Irish Sea Drift which attains its maximum effect in the Gower Peninsula.
A PARTIAL FRACTIONATION OF ALKALI‐solUBLE SOIL ORGANIC PHOSPHATE
Authors: ANDERSON GEORGE 
Published: July 2006

SummaryA study has been made of the precipitation of soil organic phosphates from alkaline extracts. Acidification to a pH of about 0.4 or below precipitated a small and constant proportion of the extracted organic phosphate. Above pH 0.4 there was an increase in the precipitation up to a pH of about z to 3. The proportion of the phosphate brought down at pH 2.9 could in some cases be increased by prior addition of aluminium sulphate, but in no case did this affect the proportion precipitated at pH 0.2. There was marked precipitation of orthophosphate above pH 3, in the presence of excess aluminium, but below pH 3 it was negligible.Inositol hexaphosphate and DNA were precipitated virtually quantitatively at pH 2.9 in the presence of added aluminium even if the extract was incubated before precipitation. Precipitation of RNA was not complete and could be prevented entirely by prior incubation of the extract. At pH 0.2 DNA was precipitated, but not inositol hexaphosphate. Less than half of a freshly purified sample of RNA was brought down, and no precipitation occurred if the RNA was allowed to stand overnight in alkaline solution before acidification.The soil phosphate esters have been divided into three main classes: an acid‐insoluble fraction precipitated at pH 0.2, and two acid‐soluble fractions, one of which is precipitated at pH 2.9 in the presence of excess aluminium, while the other remains in solution. Part of the acid‐insoluble fraction was readily mineralized during incubation in dilute sodium hydroxide, and some hydrolysis is likely during extraction of the soil with this solvent.
THE AVAILABLE‐WATER CAPACITY OF A SANDY LOAM SOIL
Authors: SALTER P. J. , HAWORTH F. 
Published: July 2006

SummaryThe effects of annual application of farmyard manure and of different cultivation treatments for a 6‐year period on the available‐water capacity of a sandy loam soil have been measured. It has been shown that the farmyard manure applications have led to a significant increase in the available‐water capacity of the soil. The cultivation treatments influenced the available‐water capacity to a lesser extent.It is suggested that the reason why many previous workers have failed to detect an increase in available‐water capacity in comparable experiments is that they did not use sufficiently accurate methods for the determination of field capacity and the permanent wilting percentage, i.e. the upper and lower limits of the available water in the soil.
THE PREPARATION AND PRESERVATION OF SOIL MONOLITHS OF THIN SECTION
Authors: CLARKE G. R. 
Published: July 2006

SummaryTechniques are described for the preparation and mounting of soil monoliths with a depth of 1‐1·5 in. The material is fixed with cellulose acetate and mounted in a way suitable for permanent exhibition. The preparation and preservation of hand specimens of special fragments are also described.
PORE VOLUME‐SIZE DISTRIBUTION AND SWELLING OF NATURAL SOIL AGGREGATES
Authors: QUIRK J. P. , PANABOKKE C. R. 
Published: July 2006

SummaryNon‐polar liquid (benzene and 1,1,2,2‐tetrachloroethane) content‐energy curves for soil aggregates have been obtained by using suction plate and pressure membrane apparatus (equivalent pF 0·5‐4·3). For low relative vapour pressure measurements a temperature differential was maintained between two connected chambers, one of which contained the soil aggregates and the other liquid benzene. The results are expressed as the volume of liquid retained in relation to the logarithm of the equivalent suction in centimetres of water (equivalent pF). This procedure enables a direct comparison to be made between the pF‐water content curves and the equivalent pF‐non‐polar liquid curve. When such comparisons are made for a number of clay soils it is apparent that 70 per cent. or more of the swelling takes place before pF 3 is attained on the wetting cycle. By differentiating the non‐polar liquid‐equivalent pF curves for a number of soil materials it has been possible to obtain the pore volume‐size distribution curves. All the clay materials gave broad peaks which extend between pF 2 and 4 and a small peak near pF 5. The peak which occurs just near pF 5 in clay soils is very pronounced for a loam soil. The peak in the coarse pore range occurs irrespective of origin and therefore appears characteristic of clay materials which have been through a number of wetting and drying cycles. The presence of this broad peak indicates that normal shrinkage cannot be expected for natural clay aggregates. The coarse pores which give rise to the broad peak can be regarded as structural pores which are eliminated by compression of the clay.
EXCHANGEABLE CATIONS AND MECHANICAL COMPOSITION OF SOLODIC SOILS OF SASKATCHEWAN1
Authors: JANZEN W. K. 
Published: July 2006

SummaryMedian values for pH, conductivity, organic and inorganic carbon, exchangeable cations, and mechanical analyses are given for seven solod profiles and eight solodic profiles. They show the A and A‐B horizons of the solod to be moderately acid, the B1 horizon to be very slightly acid to neutral, and the lower B and C horizons to be alkaline in reaction. Exchangeable Ca to Mg ratios vary from relatively high in the A to very low in the A‐B and B horizons. Exchangeable Na varies from low in the upper horizons to high in the lower. Mechanical analysis data show clay accumulation in the lower B horizons.The data for the solodic profiles are similar to the above as to pH, but the corresponding horizons are less acid. Exchangeable Ca to Mg ratios are very high throughout the profile, ranging from just over 4 in the upper A to less than 2 in the lower B. Exchangeable Na is very low throughout. Mechanical analysis data are similar to those for the solod profiles.