bluuebunny/crossref_metadata_2025 huggingface dataset:
IDENTIFICATION OF CLAY MINERALS FROM ACID SOILS
Authors: TAMURA TSUNEO
Published: July 2006

A technique is described for the identification of clay minerals, the layers of which are difficult to expand or collapse by the usual treatment with glycerol and KCl. Samples are extracted for 3 to 6 hours in normal sodium citrate at pH 7–3 and 100° C. The citrate is renewed hourly. After the citrate extraction the inter‐ layer spaces of some minerals can be expanded with glycerol and CaCl2

Basal spacings of minerals previously identified as ‘dioctahedral vermiculite’ expand to 16–18 A. after this treatment; hence, their identity is questioned.

The widespread occurrence in the north‐eastem United States of clay minerals with 14‐A. spacing necessitates this extraction for correct identification.
THE GILGAIED AND BAD‐STRUCTURED SOILS OF CENTRAL IRAQ
Authors: HARRIS S. A.
Published: July 2006

The variable soils of the recent alluvium of parts of Iraq contain horizons falling into two groups, viz. bad‐structured horizons which are hard and dense with marked vertical cracking, and well‐structured horizons characterized by a friable consistency and higher porosity. Gilgai occurs as the extreme bad‐structured phase. The only constant difference in laboratory data between these groups is the low laboratory permeability in the bad‐structured horizons. These features cannot be explained using the causes so far put forward for gilgaied soils in Australia, but they suggest an explanation of the process of formation of bad structure (in the agricultural sense) in terms of compaction by weathering agents. It is suggested as being a process which is habitually taking part in the development of solonetz soils, since the latter always seem to be characterized by this bad structure.
A SEQUENCE OF BEECHWOOD SOILS ON THE CHILTERN HILLS, ENGLAND
Authors: AVERY B. W.
Published: July 2006

The chalk and associated superficial deposits of the Chiltern Hills give rise under beechwoods to a sequence of soils ranging from rendzina through brown earth (sol lessivé) to podzol, closely paralleled in developmental sequences established elsewhere on uniform calcareous materials. The salient features of the genetic soil types represented are described and their evolution discussed in relation to vegetation and site characteristics. On base‐deficient soils, mor formation under beech is conditioned by local climatic factors and management practices as well as by inherent fertility variations and is only associated with advanced podzolization on appreciably sandy materials. On silty plateau soils with imperfect drainage, ‘micro‐podzols’, which may be transitory, are formed.
THE GEOCHEMISTRY OF BASALTIC MATERIALS AND AUSTRALIA ASSOCIATED SOILS OF SOUTH‐EASTERN SOUTH AUSTRALIA
Authors: TILLER K. G.
Published: July 2006

Four profiles in the Mt. Burr forest area of south‐eastern South Australia have been examined in detail. Two profiles were podzolized deep aeolian sands overlying buried soils which had developed on basaltic tuff, a third profile was developed on olivine basalt while the fourth was a composite profile developed on basaltic tuff and containing a buried profile formed on an earlier ash shower.

The main factors operative in influencing the geochemical distribution of the elements in these profiles were the translocation of elements by plant growth and their relative mobility on weathering, association with the clay fraction, and restricted drainage. In the aeolian sands Ca, Mn, and V with lesser amounts of K, P, Mo, Cu, Mg, Zr, and Al, were the elements which generally accumulated in the surface horizon as the result of plant action. In the surface soils of volcanic origin Ca, Mn, P, and Mg with lesser amounts of Cu and K accumulated. The highest concentrations in the clay fraction were, in general, for the aeolian sands Al, Fe, Ga, V, and Ni, and in the basaltic soils Na, Al, Ga with, to a lesser extent, K, V, P, and Ni. In the soils developed on basaltic material the elements most readily lost from the weathering zones during soil formation were in decreasing order of magnitude, Ca, P > Na, Mg, Co, Zn > Cu, Mn > Ni. K, V, Ga, Mo, Fe, Al, Ti, and Zr were in general much less mobile and tended t remain incorporated in the weathering products and concentrated in the upper weathering zones. P, Zn, and Cu and to a lesser extent Mn, Fe, Ni, Co, and Ca were found to be more readily lost on weathering under conditions of restricted drainage.

The elements most concentrated in the hardpan of a ground‐water podzol were, in decreasing order of magnitude, Fe > Al ≫ V, Zn, Ni > P, K, Mo > Na, Mn, Cu, and Ti. When the more strongly cemented nodules were separated for analysis it was found that relative to the matrix Fe > Al, V, and P, in that order, were most concentrated. Zn alone was lower in the nodules than the sandy matrix. Mn and Mo were most concentrated in the upper part of the hardpan, and Zn, V, Ni, Cu, Ti, and P in the lower part.

Some of the mineralogical changes which have taken place during the weathering of the basaltic material have been studied by examination of sand and clay fractions of the soil and thin rock sections. In the olivine basalt, the plagioclase and, to a lesser extent, olivine have weathered most readily. The main weathering products of the soil developed on the olivine basalt were kaolin and haematite. In the tuff the first important weathering product was montmorillonite, formed by the breakdown of the volcanic glass. This montmorillonite was found to break down in the upper weathering zones of the soils formed on tuff to give kaolin and goethite.
CHANGES IN THE SOIL OF A LONG‐CONTINZIED FIELD EXPERIMENT AT SAXMUNDHAM, SUFFOLK
Authors: COOKE G. W. , MATTINGLY G. E. G. , WILLIAMS R. J. B.
Published: July 2006

A four‐course rotation experiment was carried out on wheat, mangolds, barley, and legumes. Yields of all crops were much increased by phosphate fertilizers, nitrogen fertilizers increased yields of non‐legumes, extra yields from potash fertilizers were smaller. Fifty‐six years of continuous manuring caused the following changes in the calcareous boulder clay soil: Plots receiving farmyard manure contained half as much again organic carbon as plots receiving fertilizers, plots receiving N and P fertilizers contained slightly more organic matter than plots without these fertilizers. Total soil nitrogen was considerably increased by farmyard manure and was slightly higher on plots receiving sodium nitrate than on plots without nitrogen fertilizer. Total soil phosphorus was built up by farmyard manure and by bone meal, and to a smaller extent by light annual dressings of superphosphate. ‘Soluble phosphorus’ determined by three methods differentiated clearly between plots which had received phosphate fertilirs and those which had received none. An accumulation of bone meal residues was demonstrated by dilute hydrochloric‐acid extraction, but not by methods involving extraction with 0.5 M sodium bicarbonate or equilibrium with 0.01 M calcium chloride. Soluble‐phosphorus values by all three methods indicated the presence of fertilizer residues more clearly than did values for total soil phosphorus. The soil contained a large quantity of total potassium and the values were not materially affected by manuring. Dilute‐HCl‐soluble‐K and exchangeable‐K values differentiated between plots which had received potash fertilizers and those which had received none. They also reflected changes in soluble potassium caused by the different amounts of potassium removed in the crops grown.
THE BUTANA GRASS PATTERNS
Authors: WORRALL G. A.
Published: July 2006

A study has been made of the features associated with repeating bands of vegetation in the Butana region of the Sudan. Aerial observations show that they have similar features to those described by MacFadyen in British Somaliland except that the curved bands lie on the interfluves and are convex downslope.

The patterns consist entirely of grasses and herbs, and lie on very gentle slopes of about I in zoo; there is no measurable difference in elevation between the grasses and bare areas. Slopes of less than I in 500 have no patterns. The width of the bands is variable, but commonly between 8 and 12 m., and the bare ground about twice the width of the grass.

The profile consists of a grey‐brown clay loam, with an A horizon slightly lighter in colour and texture. No difference in profile, composition, or properties between the soil under grass and under bare ground has been detected, except in pH, nitrate, and moisture. There are differences in soil surface, the bare areas being smooth and the grassed areas broken by cracks and potholes which form at the beginning of the rains and concentrate just upslope of the previous season's grass. Experiments to simulate on the bare ground the moisture and growth conditions obtaining under the grass bands were partially successful.

The current season's grass concentrates at, and in advance of, the previous season's front, and there is an annual migration of the grass bands upslope. The vegetation consists dominantly of the grasses Aristida spp., Schoenfeldtia gracilis, Cymbopogon nervatus, and Sehima ischaemoides. Species of grass may have a restricted position in the grass band, the most striking being Schoenfeldtia. Herbs are more ephemeral, but are prominent during the rains in the old grass areas.

The origin of the patterns appears to be related to water supply, topography, and soil, but not to wind. Comparison with gilgai is made, but reasons are given for considering that the patterns have a different mode of origin, and an initiation due to a type of soil slip or to a rhythmic deposition of vegetation is considered possible.
WATER‐TABLE HEIGHTS IN A DRAINED HOMOGENEOUS SOIL OVERLYING AN INFINITELY PERMEABLE LAYER
Authors: YOUNGS E. G.
Published: July 2006

Drainage investigations in the past have been mostly Concerned with soils which are infinitely deep or which overlie impermeable beds, and little attention has been paid to soils which overlie a more permeable layer. Electric‐analogue experiments are described which give solutions to the particular case of a homogeneous soil, drained by a uniform system of ideal drain tubes and overlying an infinitely permeable layer, for different ratios of rainfall intensity to hydraulic conductivity and for various depths of the permeable layer below the drain level. The results are presented in terms of a correction factor which, when multiplied by the height of the water table above the drain level midway between the drain lines which would be observed if the topsoil extended to infinite depth with the same ratio of rainfall to hydraulic conductivity, gives the maximum water‐table height for a given depth of boundary between the soil and permeable layer below the drain level, expressed as a fraction of the half‐spacing of the drains. The correction factor varies with the ratio of rainfall intensity to hydraulic conductivity and the depth of the permeable layer below the drain, approaching unity as this depth increases beyond one‐third of the half‐spacing of the drains. The correction factor obtained here is compared with that obtained for the case of the soil overlying an impermeable bed for the values of the ratio of rainfall intensity to hydraulic conductivity of 0.1, 0.02, 0.05, and 0.10. The two sets of results represent the extreme cases of water‐table heights which can be observed in a two‐layered soil with the drain laid in the top layer.
THE USE OF CHELATING REAGENTS AND ALKALINE SOLUTIONS IN SOIL ORGANIC‐MATTER EXTRACTION
Authors: EVANS L. T.
Published: July 2006

The extent of organic‐matter extraction tended to rise with the pH of the extractant solution, as did the proportion of the humic‐acid fraction in the extracts. Chelating reagents extracted more organic matter than other extractants of comparable pH, but extraction by all reagents rose with increasing time and temperature of extraction. The equivalent weights of both the humic and fulvic fractions of alkaline extracts rose with the temperature of extraction, as did the extent of conversion of the humic‐acid fraction to acid‐soluble compounds. The humic‐acid fraction was flocculated by various salts to a much greater extent than the fulvic fraction. The nature of soil organic‐matter extraction is considered in the light of these results.
THE ORIGIN AND DEVELOPMENT OF BROWN EARTHS ON CLAY‐WITH‐FLINTS AND COOMBE DEPOSITS
Authors: AVERY B. W. , STEPHEN I. , BROWN G. , YAALON D. H.
Published: July 2006

Field investigation of the origin and development of three brown‐earth (sol Zessiwk) profiles has been supplemented by mechanical and mineralogical analyses and micromorphological studies. Two profiles, representative of the Batcombe and Winchester series, were on Clay‐with‐flints and the third, of the Charity series, on a Coombe deposit.

Particle‐size distribution and petrographic data strongly suggest that all three soils are derived in part from loess. The Charity is interpreted as an autoch‐ thonous profile formed in a Head deposit composed of chalky and flinty detritus mixed with loess by soliflwion, whereas the Batcombe and Winchester are two‐ stage profiles, formed in composite (non‐uniform) parent materials resulting from the superficial incorporation of loess with the truncated or redeposited remains of previously weathered horizons with rotlehm and/or braunlehm fabrics. These Clay‐with‐flint substrata contain materials derived from Chalk and Eocene beds in varying proportions, weathered in Tertiary or interglacial periods and rearranged by periglacial agencies. Clay‐with‐flints sensu stricto, as represented in the Win‐ chester subsoil, has distinctive physical, mineralogical, and micromorphological characteristics, and appears to have originated by sub‐surface solution of the Chalk and illuvial accumulation of clay derived for the most part from overlying deposits.

The land surfaces concerned have probably been subjected to at least one alternation of periglacial and temperate conditions after the addition of loess. Hence the extent to which either profile reflects the influence of the contemporary environment is not readily assessed, but evidence is adduced that the upper horizons of each profile bear the impress of similar pedogenic processes, including eluviation of clay‐size material and acidic weathering leading to the accumulation of vermiculite, modified in the Winchester by the effects of erosion and soil creep.
A MODIFIED PERMEABILITY TEST FOR MEASURING THE COHESION OF SOIL CRUMBS
Authors: DETTMANN MARGARET G. , EMERSON W. W.
Published: July 2006

The technique previously described (Emerson, J. Soil Sci., 6, 160, 1955) has been improved. A I‐cm. thickness of soil crumbs of standard size (1–2 mm. diameter) is supported on a 1‐cm, layer of glass spheres (0·5–1 mm. diameter), and the permeability measured by percolation of 0·05 N NaCl‐the so‐called ‘initial’ test. Then 3 litres of the same solution are percolated in 24 hours, after which the permeability measurement is repeated—the ‘final’ test. The ratio, K2/K1, of final and initial permeabilities of the crumbs is regarded as a measure of soil cohesion.

The technique has been applied to a wide range of soils, on some of which other structural tests had already been made. The results, in four tables, show: (a) a continuous arable system produces very bad structure; (b) a short‐term ley produces an improvement‐as does wheat‐and some of the improvement is detectable after a subsequent year in arable cultivation; (c) attainment of maximum stability is very slow, for 100 years in grass may not be enough; (d) farmyard‐manure residues increased crumb stability on a clay soil, but not on a sand;(e) a ley, and lucerne too, produces a greater increase than root crops.

Limitations of the test are: (a) It should not be used unless the soil acidity is approximately the same for all samples. Very acid clay (pH 4 to 5), known to possess a very poor structure, gives a value of K2/K1 close to unity. (b) It may not be safe to compare soils of differing clay content. A poorly structured sandy loam (12 per cent. clay) gives a much higher value of K2/Kl than a clay loam (31 per cent. clay) that field experience would assess as having the better structure.
STUDIES ON THE ORGANIC MATERIAL EXTRACTED FROM SOILS AND COMPOSTS
Authors: GOULDEN J. D. S. , JENKINSON DAVID S.
Published: July 2006

The infra‐red absorption spectra of the ligno‐proteins described in Part I of this series of papers were examined and absorption bands characteristic of the peptide link identified.

A reference sample of lignin was prepared from wheat straw and was found to be relatively unchanged by boiling with 2 N sodium hydroxide for 4 hours in the absence of air.

The infra‐red spectra of the residues from acid and alkaline hydrolysis of the ligno‐proteins were found to be very similar to that of straw lignin.
THE SOILS OF MAZANDERAN IN NORTHERN IRAN AND THEIR SUITABILITY FOR PADDY‐RICE IRRIGATION
Authors: ANDRIESSE J. P.
Published: July 2006

The soils which occur along the southern shore of the Caspian Sea, in the Mazanderan Province, which is one of the main rice‐producing regions in Iran, are formed mainly from young alluvial deposits in which pedo‐climate is considered to be the major soil‐forming factor.

According to differences in pedo‐climate, the soils have been differentiated into soil associations which are related to the topographical situation in which they occur, namely the several landscapes characteristic of the morphology of a we11‐developed riverine plain.

The occurrence of salty soils can be explained by the influence of the Caspian in the past, and their reclamation, although theoretically possible by drainage improvement, the application of soil amendments, and adequate leaching, has been found to be very difficult in practice. Soil analyses have shown interrelationships between natural vegetation or crop yield and salty conditions.

The soils have been further classified according to their suitability for paddy‐rice cultivation, particularly with regard to the economy of irrigation water.

As none of the irrigability classifications yet devised appears to be suitable for the purpose of classifying rice soils, a special system has been developed to meet the circumstances prevailing in Mazanderan.
WATER CONTENT AND SOIL STRENGTH
Authors: GREACEN E. L.
Published: July 2006

The 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

A 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

The 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

By 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

The 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

The 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

A 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

Acidic 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

A 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

Most 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

The 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

The 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

An 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

The 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

This 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

A 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

The 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

Techniques 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

Non‐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

Median 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.
EVIDENCE OF THE UPWARD MOVEMENT OF NITRATE DURING THE DRY SEASON IN THE KIKUYU RED LOAM COFFEE SOIL
Authors: ROBINSON J. B. D. , GACOKA P.
Published: July 2006

Evidence is presented to show that an upward movement of nitrate takes place in the Kikuyu red loam coffee topsoil during the hot, dry season following the main rain periods. This upward movement contributes towards the build‐up of nitrate which is observed to take place in the topsoil as it dries out.
THE ORIGIN OF THE INDURATED B3, HORIZON OF PODZOLIC SOILS IN NORTH‐EAST SCOTLAND
Authors: ROMANS J. C. C.
Published: July 2006

Morphological examination of podzol profiles in the Eastern Grampians and lowland Strathmore, together with pollen analyses of hill peat and podzol A horizons, suggest that the podzols of Strathmore have been developed since the post‐glacial climatic optimum, whilst those of the Grampians are much older.

On morphological grounds it seems improbable that the indurated B3 horizon now found in these podzolic soils could have been present in the high base status brown forest soil profiles which appear to have existed in Strathmore prior to the development of the present‐day podzolic soils.

A comparison of the stage of development of the podzol profile with indurated B3, horizon found buried beneath the earth bank around the Roman marching camp at Kirkbuddo in Angus, with the present‐day soil profile, confirms that the development of the indurated B3, horizon is related to the development of the podzol profile. Its origin must be ascribed, therefore, to pedological rather than to periglacial processes.
PHOSPHATE EQUILIBRIA IN AN ACID SOIL
Authors: TAYLOR A. WORMALD , GURNEY E. L.
Published: July 2006

A detailed study of the aluminium phosphate ion products in solutions equilibrated with an acid, phosphate‐deficient soil showed that the phosphate status of the undisturbed soil is compatible with the existence of variscite (AIPO4·2H2O) in the soil but produced no evidence that this phase has any effect in controlling the composition of dilute solutions equilibrated with the soil for periods of less than 32 days.

When the soil is acidified, subsequent changes in the composition of the solution reflect the dissolution of aluminium hydroxide and decay of the clay minerals. Phosphate additions to the acidified soil are rapidly precipitated, and the final phosphate concentration is less than would be supported by variscite under these more acid conditions.
A PUNCHED‐CARD SYSTEM FOR SOIL PROFILES
Authors: MUIR J. W. , HARDIE H. G. M.
Published: July 2006

A punched‐card system, designed to make data on a large number of profiles readily available, is described. The problems of converting the data to a form suitable for punching on the card are fully discussed. A numerical code is used to group the profiles according to soil series, major soil group, or geographical location. Analytical results of various kinds are also coded for each major horizon. A feature of the system is that information on a complete profile is coded on one card so that the profile remains the basic unit.
A NOTE ON THE CHEMICAL ANALYSIS OF A SOIL BURIED SINCE ROMAN TIMES
Authors: MATTINGLY G. E. G. , WILLIAMS R. J. B.
Published: July 2006

The chemical composition of a soil buried beneath a Roman amphitheatre was compared with soil from the surrounding field and with the materials from which the amphitheatre was constructed. The calcium carbonate and total potassium contents of the buried soil and the cultivated surface soil were similar. The buried soil contained 0·78 per cent. carbon, 0·126 per cent. nitrogen, and 0·044 per cent. organic phosphorus and the surface soil 2·42 per cent. carbon, 0·318 per cent. nitrogen, and 0·097 per cent. organic phosphorus. Much more phosphorus, soluble in 0·5 M sodium bicarbonate, was present in the buried soil (12·8 mg. P/100 g.) than in the surface soil (1·3 mg. P/100 g.). Losses of nitrogen since the soil was buried in Roman times were estimated to be about 70 per cent.
SOME EFFECTS OF RAINFALL, RADIANT DRYING, AND SOIL FACTORS ON INFILTRATION UNDER RAINFALL INTO SOILS
Authors: ROSE C. W.
Published: July 2006

The effect of the structural condition of a soil on infiltration under laboratory simulated rainfall was investigated. Infiltration was greater with better structural condition for both undisturbed and disturbed samples. The infiltration rate of a soil surface damaged by intense rainfall decreases as rainfall continues. After equal periods of exposure there was little difference, for any of three soils examined, between total infiltration of rainfall at a rate of 6 in. per hour and at 4 in. per hour. The application of a pressure less than atmospheric to the underside of 2‐in.‐deep samples, simulating the moisture tension observed in the transmission zone on infiltration into deep soil columns, did not increase infiltration under rainfall as would be expected. For a clay soil previously exposed to rainfall, infiltration rate after radiant drying for 24 hr. and rewetting was only half that of replicates which were dried in shade.

The nature of the cation with which a soil may be saturated markedly affects the permeability of the soil to water; and this effect persisted when water was applied with the added mechanical action of falling drops. Artificial crumbs of pure clays and a clay mixture were brought to moisture equilibrium with saturated water vapour, and their stability under rainfall examined. Calcium‐saturated kaolin crumbs were rapidly broken down and dispersed under rainfall, in marked contrast to their stability on immersion in water without the mechanical effect of falling drops. Calcium‐saturated illite and montmorillonite experienced no visible breakdown of the crumbs and no dispersion for the same rainfall exposure.
AN ESTIMATION OF MICROFAUNAL POPULATIONS IN SOILS AND FOREST LITTER
Authors: STOUT J.D.
Published: July 2006

In mineral soils the microfaunal population consists principally of nematodes and protozoa. The ciliate protozoa tend to be more numerous than the rhizopods. In beech‐litter rotifers and copepods are also very numerous. There is a significant difference between the litter populations of summer and winter.