bluuebunny/crossref_metadata_2025 huggingface dataset:
THE ALKALINE NITROBENZENE OXIDATION OF SOIL ORGANIC MATTER
Authors: MORRISON R. I.
Published: July 2006

The yields of syringaldehyde, vanillin, and p‐hydroxybenzaldehyde obtained by alkaline‐nitrobenzene oxidation of soil organic matter indicate the extent to which lignin‐derived material is present. A number of soils, peats, and peat fractions have been oxidized by this method and the phenolic aldehydes formed have been separated and determined by a‐ micro‐technique. The results indicate the presence in soil organic matter of significant amounts of syringyl, guaiacyl, and p‐hydroxyphenyl residues which are almost certainly derived from lignin. The yields of aldehydes from mineral soils accounted for about 0.5–1.0 per cent. of the total organic carbon; from peats for about 1.0–4.0 per cent. There was evidence of a correspondence between the relative amounts of the three aldehydes obtained from the soil organic matter and from the parent plant material. The results for a peat profile indicated a tendency for the yield of aldehydes to increase with depth of the horizon; the reverse was found with a pine‐forest soil profile. Peat fractions all gave some aldehydes on oxidation, but there were marked differences in the levels; the highest yield, almost 7 per cent., was obtained from a humic‐acid fraction soluble in ethanol‐benzene. Hydrolysis of the humic‐acid fractions with dilute hydrochloric acid markedly depressed the yields of aldehydes obtainable on oxidation.
CARBON STUDIES ON THE IRRIGATED SOILS OF THE SUDAN GEZIRA
Authors: JONES T. A.
Published: July 2006

The seasonal variation in the organic‐carbon content of Gezira soil under irrigated rotational cropping has been studied over three successive years. Emphasis has been placed on the cotton phases of the rotations. Significant differences in organic carbon occuring between rotations did not produce differences in degrees of nitrogen fixtion. It is suggested that fixation and mineralization of nitrogen occur so rapidly in this soil that it is not possible by chemical analysis to determine the amount of nitrogen fixed.

Seasonal changes in organic‐carbon content display a phase of slow fluctuation when the soil is wet and carries a crop, and a phase of rapid fluctuation when the soil is bare, dried by insolation, and cracked. Attention is drawn to this phase and to the need for better understanding of the associated phenomena which contribute to the maintenance of high fertility in these arid soils.
SOME FACTORS DETERMINING WATER‐TABLE HEIGHTS IN DRAINED HOMOGENEOUS SOILS
Authors: COLLIS‐GEORGE N. , YOUNGS E. G.
Published: July 2006

The effect of the depth of impermeable floor below the drain level on water table heights in homogeneous soils, drained by a uniform system of ideal drains, for steady state conditions with various rainfall intensities, was investigated by means of hydraulic model and electric analogue experiments. Agreement was obtained between the two series of experiments which indicated that, for a given ratio of rainfall intensity to hydraulic conductivity, the water‐table height midway between the drains decreased as the depth of the impermeable floor below the drain was increased from zero, tending towards a constant height when the ratio of the depth of the impermeable floor below the axis of the drain tube to the half spacing of the drains approached 0.3. In addition, in the experiments with a deep impermeable floor, agreement was found with the analytically obtainable solution of the problem with an infinitely deep floor. Water‐table heights observed in the non‐steady state hydraulic experiments approximated to those of the steady state with uniform distributions of flux cutting the water table for corresponding equal mean distributions, calculated from the drain discharge.
THE RUSSIAN APPROACH TO SOIL CLASSIFICATION AND ITS RECENT DEVELOPMENT
Authors: BASINSKI J. J.
Published: July 2006

Due largely to the conditions in which they were working, Russian pedologists were the first to establish pedology as an independent science. From the beginning they regarded soil as an independent body with a definite morphological organization, expressed mainly in the structure of the profile, and resulting from pedogenetic processes determined and directed by environmental factors. This concept of soil led them to adopt a genetic approach to problems of soil classification. Russian soil classifications differed according to the basis accepted, whether bioclimatic, geographical conditions, factors of pedogenesis, pedogenetic processes, or soil evolutionary history. In recent years attempts have been made to construct classification systems based on all these aspects of pedogenesis. The current Soviet trends in soil taxonomy must be regarded mainly as a further development of the traditional approach. Measures are taken to standardize soil nomenclature and improve methods of recognizing (diagnosing) and describing soil types, which are regarded as basic taxonomic units. The evolutionary‐genetic approach is considered the only proper approach to soil‐classification problems. The importance of organic aspects of soil evolution and formation processes is emphasized. More attention is given to the genetic subdivision of soil types into smaller and better defined soil groups. Interest in the systematics of cultivated soils is also growing.
STIMULATION OF BACTERIAL PROTEOLYSIS BY ADSORBENTS
Authors: ESTERMAN EVA F. , McLAREN A. D.
Published: July 2006

A comparison of the initial rate of NH, production from protein adsorbed on kaolinite and non‐adsorbed protein by bacteria showed that adsorption enhanced the rate. This effect occurs with both adsorbed and non‐adsorbed organisms, and disappears when a non‐adsorbed substrate (denatured lysozyme predigested by chymotrypsin) is used. With Flavobacterium sp. the effect occurred with a dilute inoculum and disappeared with a concentrated one. Shaking cultures of Flavobacterium sp., which ordinarily is c. 98 per cent. adsorbed to kaolinite, and of Pseudomonas sp., which is only c. 30 per cent. adsorbed to kaolinite statically, which might dislodge organisms from the clay, did not decrease rates of NHs liberation. It is concluded that the kaolinite acts as a concentrating surface for adsorbed substrate and exoenzymes, and thereby brings about a more rapid break‐down of substrate. Flavobacterium sp. readily attacks protein adsorbed on bentonite with a resulting decrease in (001) X‐ray diffraction spacing.
MOLYBDENUM IN THE LOWER LIAS OF ENGLAND AND WALES IN RELATION TO THE INCIDENCE OF TEART
Authors: LE RICHE H. H.
Published: July 2006

An explanation is offered for the fact that the toxic levels of molybdenum occurring in the Lower Lias soils of Somerset have not been found in soils of Glamorgan, apparently derived from the same zones of the Lower Lias. This is attributable to the parent rock being free of the abnormally high levels of molybdenum found in Somerset, which in turn probably results from the Glamorgan Lias having been laid down close to the contemporary coastline.

Soils high in molybdenum are to be expected in the Vale of Marshwood (Dorset), but owing to the topography of this district they probably occur in such small pockets as to cause no serious trouble.
SOIL CLASSIFICATION—A DESTRUCTIVE CRITICISM
Authors: JONES T. A.
Published: July 2006

Attention is drawn to the theoretical and practical errors associated with the use of the profile as the working tool of soil classification. It is claimed that the planar characteristics of the profile are fundamentally inappropriate for depicting the four‐dimensional qualities of soil. The concept of the modal profile is discussed, in particular its role in encouraging a ‘calculus’ approach to a soil classification constructed from an infinite number of finite units. It is suggested that a workable system of soil classification will be possible only by adopting some new approach completely free of the basic defects of the ‘soil‐profile’ approach.
THE EFFECT OF ORGANIC MATTER ON CRUMB STRUCTURE
Authors: EMERSON W. W. , DETTMANN MARGARET G.
Published: July 2006

Tests made on soil crumbs from nearby long‐term arable and grassland fields have shown that (a) the rate of water uptake of dry crumbs at 98 per cent. relative humidity was the same for arable and grassland crumbs and also grassland crumbs pretreated with H2 O2; (b) the degree of swelling of dry arable and grassland crumbs in water is the same. It is concluded that the crystalline swelling of the clay in soil crumbs is unaffected by the soil having been under grass. No difference could be observed in the general arrangement of the quartz and orientated clay in thin sections of arable and the corresponding grassland crumbs.

From slaking and dispersion tests made on the natural crumbs and on remoulded crumbs formed by drying from a paste of the natural crumbs it is inferred that remoulding does not disperse the clay in either the grassland or arable crumbs, but does break‐up many of the aggregates between 50 μ and 2 μ diameter in the grassland crumbs. The natural arable crumbs were so weak that immersion wetting of the dry crumbs was sufficient in itself to cause this break‐up.
HUMIC‐ACID INVESTIGATIONS
Authors: COULSON C. B. , DAVIES R. I. , KHAN E. J. A.
Published: July 2006

Paper and column chromatography using partition and ion‐exchange conditions, high‐ and low‐voltage paper electrophoresis, and gelatine‐gel diffusion have all been used in an attempt to fractionate humic acids, but only limited success is recorded.
AMORPHOUS IRON OXIDES IN SOILS
Authors: TAYLOR R. M.
Published: July 2006

The identification of amorphous iron oxides in soils has often been based on a sharp exothermic peak at about 320°C. on D.T.A. records. This peak was given by several samples in the present study; in each case it was due to the organic matter present. This was only removed by prolonged treatment with concentrated H2O2, though the exothermic reaction was suppressed by using a nitrogen atmosphere in the furnace. The free iron oxides in these same soils are fully accounted for by the crystalline iron minerals present. It is suggested that previous analyses reporting amorphous iron oxide be viewed with caution.
STUDIES ON A NIGERIAN FOREST SOIL
Authors: BATES J. A. R.
Published: July 2006

Features of the profile of a mid‐slope forest soil typical of the red concretionary variant of the Iwo Series, which is common in Western Nigeria, are the well‐defined gravel horizon from 7 to 50 in., and the sandy horizon above it.

The carbon content in the top 2 in. is 3.95 per cent. There is a very sharp fall to 0.38 per cent. below 2 in. The percentage carbon then decreases slowly down the profile. The C/N ratio is also high in the worm casts (15.7) and topsoil (13.6); below z in. it is much lower, and falls to 3.1 at 60 in. Both the root growth and worm activity are confined to the top few inches of the profile.

The pH in the 0–2 in. horizon is 7.7, representing a considerable accumulation of bases in the surface soil. Below 2 in. the pH is fairly constant at about 6.7 down to 50 in., when it falls again to 5.6.

Although contributing only 2.5 per cent. to the weight of the top 4 in. of soil, the plant residues comprise 17.3 per cent. of the organic matter in this layer. Most of the organic matter, however, is in the coarse‐silt aggregate fraction. After removal of plant residues, the C/N ratio of the remaining fine‐earth fractions falls as the particle size of the fraction decreases.

Aggregation in the surface soil is caused by organic matter, but at 20–30 in. aggregation is due to the high free iron oxide. Extraction of the aggregate fractions with 0.5 M sodium hydroxide and 0.1 M sodium pyrophosphate (pH 7) indicates the varying nature of the organic matter in these fractions.
SOIL‐FOREST TYPES OF THE YUKON AND TANANA VALLEYS IN SUBARCTIC ALASKA1
Authors: WILDE S. A. , KRAUSE H. H.
Published: July 2006

The region consists of flood plains, river terraces, low mountains, and dissected plateaux. Much of the area is covered with wind‐blown, micaceous silt and fine sand. The summer temperature of nearly 100° F. drops in winter to ‐ 70°. The mean annual precipitation is about 12 in. The important types of forest soils include lithosols and regosols, alluvial soils, melanized raw‐humus soils, micro‐podzols, half–bog soils, lowmoor peat, highmoor bog soils, and tundra‐forest soils. Forest cover consists of white and black spruce, tamarack, paper birch, aspen, and tacamahaca poplar, accompanied by Sitka alder, willows, Alaska rose, highbush cranberry, many heath shrubs of both American and Eurasian origin, mosses (largely of Sphagnum and Hylocomium genera), and lichens.

Spruce stands on productive loessial uplands and permafrost‐free terraces yield as much as 15 Mbf. per acre. A comparatively rapid growth of trees on lithosols and regosols, attaining 0.3 cords per acre per year, is attributed to large differences between the day and night temperatures resulting in condensation of water on fissures and fragments of rocks. Highmoors, covering slopes up to 45°, and some half‐bog soils support sporadic cover of dwarfed trees; these otherwise unproductive sites provide food and shelter for wildlife, an important item in Alaska's economy.

The immediate neighbourhood of highmoor peat and alkali solonchak soils, as well as the development of non‐podzolic, melanized soils covered with thick raw humus, are among many paradoxes of the Alaskan environment.
TRACE‐ELEMENT DISTRIBUTION IN SOIL PROFILES
Authors: SWAINE D. J. , MITCHELL R. L.
Published: July 2006

The contents of total and extractable trace elements present in Scottish soil profiles are primarily related to the geological parent material from which the soils are derived. Little or no effect within the profile attributable to pedological factors has been observed in the total contents. The most marked effect on the contents of extractable trace elements, notably Co, Ni, Cu, Mn, Mo, Zn, and Pb, is their increased mobilization in conditions of restricted drainage. Very high extractable contents occur in gleyed horizons of very poorly drained soils. No marked accumulation of trace elements has been observed in the iron pan or illuvial horizons of podzolized profiles. Higher contents of acetic‐acid‐extractable Al occur in soils with unrestricted drainage, the amounts present being of the same order as the exchangeable‐Ca contents.
CHEMICAL STUDIES OF PODZOLIC ILLUVIAL HORIZONS
Authors: MARTIN A. E. , REEVE R.
Published: July 2006

A study of the effects of pH and of carbon/aluminium ratio on the flocculation of podzol humus by aluminium is reported. Portions of resin‐treated humus extracts were adjusted to selected pH values (which varied from 1·8 to 7·0) and mixed with equal volumes of AlCl3 solutions at the same initial pH. The C/Al ratios employed were varied from 1·5 to over 20.

At C/Al ratios of 16, using B‐horizon humus from an Australian podzol, complete precipitation of C and Al occurred only at pH 4‐4·5, i.e. at about the precipitation pH of hydrous aluminium oxide. As the pH was decreased below 4, increasing amounts of C (up to 25 per cent. of that added) and Al (up to 95 per cent.) remained in the supernatant liquid. As the pH was increased above 4·5, all, or nearly all, the added C and Al remained unflocculated. At C/Al ratios of 20 or more, no precipitation of either constituent was found at any pH employed. At a C/Al ratio of 16, only partial precipitation of humus and Al occurred which was maximal at pH 2·5. Similar results were obtained for humus from a New Zealand podzol although it was less sensitive to flocculation.

After mixing the two phases, changes in pH occurred which were independent of C/Al ratio, degree of flocculation, or humus type, but which depended on the mean pH of the C and Al systems before mixing. Negative pH changes were recorded below pH 4·5 while above this value positive differences were found. A detailed analysis of these changes suggested the participation of polymeric hydroxy‐aluminium complexes in humus flocculation at pH 3·5‐4·5, whereas below pH 3·5 flocculation is probably brought about by free Al ions. Evidence is presented for the exchange of humus ‘anions’ for hydroxyl on the surface of freshly formed Al hydrous oxide at pH values over 4·5.

A brief study of the sorption of podzol humus by Al‐bentonite and by Na‐H‐bentonite is described. Sorption by Al‐clay was maximal and complete from pH 2·0 to pH 3·0, but above this increasing amounts of humus remained unsorbed. Interpretation of the pH changes in these systems was complicated by lack of equilibrium conditions. Pure H‐clays (prepared by resin treatment of clay suspensions) showed decreasing sorption from 50 per cent. at pH 2 to practically zero at pH 4·5 or greater. It is suggested that sorption of organic matter by clays in acid soils is facilitated by the presence of exchangeable or surface‐sorbed Al.

Humus suspensions showed considerable deflocculating properties towards H‐ and Al‐clays. This factor may be important in clay migration in soils.
DETERMINATION OF ORGANIC CARBON IN SOIL
Authors: BREMNER J. M. , JENKINSON D. S.
Published: July 2006

The organic carbon contents of a range of soils and of various organic materials (mostly of plant origin) were determined by the titrimetric methods of Tinsley and Walkley and Black, and the results compared with those obtained by Shaw's wet combustion method. Tinsley's method gave more reliable results with soils than Walkley and Black's method, but neither is satisfactory for precise work. Both give high results with organic materials less oxidized than elemental carbon and low results with organic materials more oxidized, although this effect is masked with materials which do not react completely under Walkley and Black conditions. Quantitative results were obtained on a range of whole plant materials with both Tinsley's and Walkley and Black's methods. The latter thus provides a very rapid method for the determination of carbon in plants. The carbon contents, determined by Tinsley's method, of a range of pure organic compounds agreed with the predicted values. Tinsley's method does not give quantitative results with certain soils, partly because of the oxidation level of the organic matter in these soils and partly because oxidation is incomplete.
IRON AND THE Eh OF WATERLOGGED SOILS WITH PARTICULAR REFERENCE TO PADDY
Authors: JEFFERY J. W. O.
Published: July 2006

Assuming a simple ferro‐ferric redox system in a waterlogged soil containing active organic matter, the equation Eh= (1.28±0.03) − is derived and some evidence is brought to support it.

The term is three times greater than that commonly used when adjusting soil Eh measurements for pH change.

The author recommends that both Eh and pH values should be invariably quoted as measured, and a third term included for the adjusted Eh if necessary.

The equation is also used to suggest the importance of pH changes when considering the movement and precipitation of iron in aerated soils.
SOIL STUDIES AT SWAN HILL, VICTORIA, AUSTRALIA
Authors: LAYERING I. SOIL , CHURCHWARD H.M.
Published: July 2006

Much of the variation in soil profiles at Swan Hill is due to the superposition of soils (one upon the other).

This paper deals with the principles by which interlayer variations may be distinguished from intralayer variations. The latter have an interdependence corresponding to the eluvial‐illuvial relationship, whilst the former show a discordant and even random relationship. The discordant relationship between layers is due to the variable truncation (by erosion) of each soil layer prior to its burial by further depositional material. In the riverine layers there has been no erosion, and soils overlie one another conformably. Their distinctness is proved by the recurrence of eluvial‐illuvial patterns of distribution down the vertical axis. The regular waxing and waning of morphological features–cutans, pedality, visible porosity, and coherence–are used as diagnostic features.
CHEMICAL DISCRIMINATION OF TERRA ROSSAS AND RENDZINAS
Authors: OERTEL A. C.
Published: July 2006

One of the discriminant functions of mathematical statistics is used in a re‐examination of the chemical features of some terra rossas and rendzinas from South Australia. The results indicate that these soils constitute a bimodal group chemically. Dichotomy is therefore justifiable on chemical as well as on mor‐phological grounds.

The use of a discriminant function in taxonomic work is illustrated by an application to some extra‐Australian terra rossas and rendzinas. The result suggests that soils with similar morphological features usually have similar chemical features.
INVESTIGATIONS ON RICE‐GROWING IN BRITISH GUIANA
Authors: GASSER J. K. R.
Published: July 2006

An attempt has been made to account for the different soil types which are derived from alluvial material of similar age and origin. The sequence noted was undifferentiated alluvium (frontland clay soil), humose clay (pegassy‐clay soil), thin organic soils (pegasse). The subsoil varied from that similar to frontland clay to a bleached yellowish‐white structureless clay. Differing durations and intensities of flooding were considered to be responsible for the changes in the subsoil. With permanent flooding, plant residues accumulate on the surface and the soil is more rapidly leached. Less organic matter accumulates and less leaching occurs with seasonal flooding. Reefs of dry sand and other soils develop under special conditions and, as they do not belong to the general sequence, are described separately.
PEDOGENESIS OF SOME RED‐BROWN EARTHS BASED ON TRACE‐ELEMENT PROFILES
Authors: OERTEL A. C.
Published: July 2006

The clay profile of six red‐brown earths of South Australia formed from sedimentary material was not produced by an eluvial‐illuvial process. Analytical data for trace elements provide convincing evidence that the present amount of weathering per unit mass of the parent material decreases with increasing depth throughout the B horizons and that at least all but an insignificant part of the clay content of these horizons was formed in its present position. Most of the clay formed from the surface layers of the parent material has been lost. All observations are accounted for in a simple and straightforward manner.

This result casts doubt on the validity of the term ‘illuvial horizon’ for any similar soil.
THE GENERAL PRINCIPLES OF CLASSIFICATION WITH REFERENCE TO SOILS
Authors: MUIR J. W.
Published: July 2006

Natural and artificial systems of classification are defined. One of the most advanced natural systems of classification is the Periodic Classification of the Elements and its development is traced so that it can be used as a framework of reference for other systems of classification, in particular those for plants and soils. It is demonstrated that plant classification is also a mature system, but soil classification is still in an elementary stage of development. The strengths and weaknesses of two recently published systems, the Soils of Europe by Kubiena and the 7th Approximation by the Staff of the U.S. Soil Survey, are discussed.
INCIPIENT FAILURE OF SOIL AGGREGATES
Authors: QUIRK J. P. , PANBOKKE C. R.
Published: July 2006

A comparison of the rate of wetting of aggregates taken from a virgin and continuously cultivated Red‐brown Earth has been made. The aggregates were placed on a glass sinter which was connected to a horizontal capillary. The rate of water uptake was obtained from the rate of meniscus travel as water was adsorbed from the sinter by the aggregates.

When air‐dry (P/P0≊ 0·50) aggregates were wetted at 2 and 10 cm. water suction the cultivated aggregates wetted more rapidly than the virgin aggregates. At a suction of 30 cm. both groups of aggregates exhibited almost identical rates of wetting. The difference in the rate of wetting could not be attributed to differences in pore structure since both groups of aggregates had almost identical total porosity and clay content and furthermore showed extremely similar rates of wetting when wetted at a low suction with a non‐polar liquid. When aggregates from a virgin and cultivated soil were wetted slowly the pF‐water content relationship was very similar; it was therefore concluded that organic matter did not give rise to a finite contact angle for the water advancing into the virgin aggregates.

Because the cultivated aggregates when wetted at 30 cm. and then at 2 cm. ion did suctnot slake when placed in water, whereas cultivated aggregates wetted directly to 2 cm. suction from the air‐dry condition slaked when placed in water, the phenomenon is described as incipient failure. When the cultivated aggregates are wetted at 2 cm. suction the work done by the rapid wetting causes planes of failure to be set up and the soil moves from an over‐consolidated condition to that represented by the n o d or virgin consolidation curve (Croney and Coleman, 1954). It is proposed that the organic matter in the virgin aggregates strengthens the pores against failure and so this material retains its initial pore structure. Mechanical strength measurements on virgin and cultivated aggregates support this hypothesis.
DEVELOPMENT OF HYDROMORPHIC HUMUS PODZOLS AND SOME NOTES ON THE CLASSIFICATION OF PODZOLS IN GENERAL
Authors: DAMMAN A. W. H.
Published: July 2006

Hydromorphic humus podzols can develop under submerged conditions as a result of internal water movement, and their development is by no means dependent on the occurrence of a water table which descends, periodically, below the B horizon. The basic difference between podzolization under anaerobic and aerobic conditions is stressed, and it is suggested that classification of the podzols be based in the first place on these two processes, using the humus content of the B horizon for a further subdivision. It is pointed out that the humus content of the B horizon is unsuitable for the primary subdivision since it is governed by a number of independent factors.
CRITERIA FOR CLASSIFYING TROPICAL SOILS BY AGE
Authors: WAMBEKE A. R. VAN
Published: July 2006

Three soil properties are proposed as criteria for distinguishing tropical and equatorial soils according to the age of their parent materials. The criteria are structure, silt‐clay ratios, and percentage of weatherable minerals. Assessments thus made agree well and conform closely to assessments based on geomorphology in Central Africa.
TERRACE CHRONOLOGY AND SOIL FORMATION ON THE SOUTH COAST OF N.S.W.
Authors: WALKER P. H.
Published: July 2006

Cyclic terraces and their soils developed in steeply graded drainage areas and gently sloping floodplains at the same time as the K‐cycle soil layers in the adjacent hill country. The K3 sediments are by far the greatest in volume while the K2 and K1 sediments are progressively smaller in volume.

Radiocarbon dates for four terrace sites show that the K3 cycle commenced 29,000 years ago, the K2 cycle 3,740 years ago, the K1 cycle 390 years ago, and the present epicycle of erosion K0 0‐120 years ago. These dates do not correlate with the dates of past climatic events proposed by other Australian workers. They do show, however, that the soils on the N. S.W. south coast are rarely older than late Pleistocene.
WATER‐SUCTION CURVES OF LARGE‐GRAINED AGGREGATES
Authors: NAAR J. , WYGAL R. J.
Published: July 2006

Water‐suction curves of large‐grained aggregates, when obtained from small samples, often do not represent the true moisture characteristics of the material. Gravity segregation of the fluids within the sample may cause the average moisture content to vary significantly from the true value that might be obtained could the measured suction be applied uniformly. A method for correcting these curves was derived to interpret correctly experimental results on such aggregates.
COPPER‐DEFICIENT SOILS IN SOUTH‐EAST SCOTLAND
Authors: PURVES D. , RAGG J. M.
Published: July 2006

The copper‐deficiency condition in cereals known as‘wither‐tip’has been found in a limited area in south‐east Scotland during the past ten years. This condition has been consistently associated with a low level of total copper in the surface horizon.

The distribution of‘wither‐tip’and low copper content is directly related to the presence of one soil type, namely Eckford series, within the fields in question.

Analysis of IOO surface soils sampled in south‐east Scotland suggests that a substantial proportion of the fields in this region are copper deficient or potentially copper deficient.
THE SOILS OF ISRAEL AND THEIR DISTRIBUTION1
Authors: DAN JOEL , KOYUMDJISKY HANNA
Published: July 2006

The main soil groups present in Israel are listed, their geographic distribution is described and related to pedogenic factors. Three physiographic‐lithologic regions are recognized: the coastal region, the mountain and hill region, and the valleys, plains, and plateaux. Climate ranges from Mediterranean in the north to extremely arid in the south. Depending upon climatic conditions in each of the physiographic‐lithologic regions, climatogenic soils range from those characteristic of the Mediterranean region (noncalcic brown soils, terra rossa, brown rendzina, grumusols) in the north to desert soils (serozem, hammada) in the south.
THE EFFECT OF FARMYARD MANURE ON THE MOISTURE CHARACTERISTIC OF A SANDY LOAM SOIL
Authors: SALTER P. J. , WILLIAMS J. B.
Published: July 2006

Annual applications of farmyard manure for 7 or 8 years have led to a significant increase in the available‐water capacity of a sandy loam soil and in the volume of water released at low tensions. The available‐water capacity increased, and the moisture characteristic altered, as the soil became more compacted during crop growth in both 1960 and 1961, and differences in moisture characteristics between the manured and unmanured soil were greatest at the harvest time of the crop.
SOIL CLASSIFICATION
Authors: DUCHAUFOUR Ph.
Published: July 2006

The author compares the 7th approximation of the American Soil Classification with the French system. Although the two systems rest on different bases, the American Classification of 1960 stands out as a spectacular rapprochement with the European Classifications.
CALCULATION OF NEGATIVE AND POSITIVE ADSORPTION IN SOME CLAY ELECTROLYTE SYSTEMS
Authors: HELMY A. K.
Published: July 2006

Calculations are presented of the fraction of charge compensated by cations for some clay systems. Surface charge density, electrolyte type, concentration and composition are studied in their relation to positive adsorption and exchange of cations in some clay systems. It is calculated that the negative adsorption due to mono‐valent anions is about one‐third that due to divalent ones present at the same concentration.
MECHANISMS OF FORMATION OF SODIUM CARBONATE IN SOILS
Authors: WHITTIG L. D. , JANITZKY P.
Published: July 2006

Mechanisms of formation and accumulation of Na2CO3 have been studied in a graded sequence of salt‐affected soils of the Sacramento Valley, California. The soils are confined within a drainageway which is inundated during winter with flood waters containing relatively low concentrations of neutral sodium, calcium, and magnesium salts. Heavy inundations and high water tables within the basin lead to microbiological reduction of sulfate and ferric iron. The resulting sulfide is held within the soil as FeS whereas the CO2 released by biological oxidation of abundant organic matter forms bicarbonate. Lateral and upward migration of bicarbonate‐charged water from the drainageway basin to soils nearer the basin rim results in yearly increases in concentration of soluble salts within these soils. Ca(HCO3)2 and Mg(HCO3)2 migrate from the zones of maximum CO2 production and precipitate as carbonates. NaHCO3 continues to move, along with the capillary water, and accumulates in the rim soils. As water evaporates or is used by growing plants, loss of CO2 from the NaHCO3 occurs, resulting in the formation of Na2CO3. The high Na2CO3 concentration at these rim positions has resulted in removal of divalent bases from the exchange complex, an equivalent increase in exchangeable sodium, and high pH.
STUDIES ON SOIL POTASSIUM
Authors: TINKER P. B.
Published: July 2006

The composition of the topsoil in Nigerian oil palm plantations is expected to be closely related to the potassium status of the palms. K‐(Ca±Mg) activity ratios obtained from the equilibrium solution data presented in Part III of this series were not related to potassium yield response in field experiments on highly acid soils. This conclusion is supported by the failure of liming to affect potassium response, though the equilibrium activity ratios of acid soils are strongly affected by it.

A relationship was found between yield response and the K‐(Ca±Mg) activity ratios of the soils determined in presence of sufficient lime water to remove soluble aluminium.

A better relationship was obtained between yield response and a ‘unified activity (K±) ratio’
image

, called ARu, the activities being those found in the true equilibrium solutions. ARu was found to be far less dependent on exchangeable Ca±Mg than the K‐(Ca±Mg) activity ratio.
TOXICITY AS A CAUSE OF THE INEFFICIENCY OF UREA AS A FERTILIZER.
Authors: COURT M. N. , STEPHEN R. C. , WAID J. S.
Published: July 2006

Plant damage and reduced yields were associated with delayed ammonification or nitrification of added urea‐nitrogen. In a neutral sandy loam, the adverse effects of urea application were associated with the accumulation of toxic levels of first ammonia and later nitrite. Addition of hydrogen‐ion as phosphoric or sulphuric acid alleviated the damage thereby supporting the conclusion that ammonia and nitrite accumulation were the causes of phytotoxicity. In an acid sand, toxicity was associated first with the presence of large quantities of urea remaining in the soil though the evidence was insufficient to show in what way the urea was toxic. There was then a second phase of toxicity associated with the presence of considerable quantities of ammonium‐nitrogen under conditions where toxic levels of ammonia were likely to have occurred. The later phase (nitrite toxicity) did not occur. Phytotoxicity arising from urea addition to the soil could be due apparently to the persistence of urea as such in the soil and also to the accumulation of significant quantities of free ammonia and nitrite. The occurrence of one or more of these phases of urea toxicity depended on differences in soil conditions.
SOILS OF THE ULTRA‐BASIC ROCKS OF THE ISLAND OF RHUM
Authors: RAGG J. M. , BALL D. F.
Published: July 2006

Ultra‐basic and basic igneous rocks outcrop as a complex over about 20 square miles of the island of Rhum, off the west coast of Scotland. Here in a cool wet oceanic climate, where the annual rainfall varies from 55 to 130 inches, there has developed a sequence of soils from rankers to peat podzols or braunerden. The development is not a simple time relationship at a particular site because of the existence of a complex erosion, transport, and deposition cycle. There is evidence for a previous long stable period succeeded by more intense erosion, possibly ascribable to past land‐use. The podzols differ from typical podzols in having no AB horizon, high pH values, and high contents of exchangeable cations, especially magnesium.
MECHANISMS OF FORMATION OF Na2CO3 IN SOILS
Authors: JANITZKY P. , WHITTIG L. D.
Published: July 2006

Biological transformations have been responsible for formation of Na2CO3 and resultant high alkalinity in some of the salt‐affected soils of the Sacramento Valley, California. Environmental factors favouring Na2CO3 formation are high ground‐water level to provide an anaerobic environment, supply of Na2SO4, and organic matter. Under these conditions, anaerobic micro‐organisms reduce sulphate to sulphide and oxidize organic matter to CO2. The sulphides hydrolyse to produce free OH which combines with CO2 to form HCO3. Reduced Fe in the system inactivates the sulphides and allows accumulation of NaHCO2. Loss of CO2 from NaHCO2 during dry periods of the year results in formation of Na2CO3.

In the laboratory an anaerobic environment and a supply of readily decomposable organic matter have been shown to be essential for development of HCO3 and CO3. Ultimate development of high alkalinity depends upon inactivation of soluble and exchangeable divalent bases as precipitated carbonates. Inactivation of divalent bases favours a high exchangeable Na content as well as build up of soluble NaHCO3 and Na2CO3.

There is an equivalent relationship between the amount of SO4 reduced and HCO3 formed by the processes involved. The anaerobic organisms involved in the transformations obtain oxygen from the SO4 and in turn oxidize carbon of the organic matter to CO2.

Development of HCO3 and CO3 is favoured in situations where organic matter and Na2SO4 concentrations are both high, but is limited in systems with a relatively low organic matter content and a high concentration of Na2SO44, or conversely, when a high content of organic matter is combined with a low salt concentration.
A PHYSICO‐CHEMICAL STUDY OF THE PROPERTIESOF HUMIC ACIDS AND THEIR CHANGES DURING HUMIFICATION
Authors: VISSER S. A.
Published: July 2006

Humic acids extracted from decomposing plant and peat core samples and changes in them during the process of humification were investigated in terms of their elementary composition, the acidity and the equivalent weight, the infra‐red, visible and ultra‐violet spectra and the shape and size of the molecules and their weight. With progressive humification in peat and decomposing plant samples, increases were noted for the carbon content and the aromatic character of the humic‐acid molecules and in the number of their alcohol and ether groups, aliphatic side chains and double bonds, while decreases were observed for the hydrogen content, the molecular weight, the equivalent weight, and the hydrophilic character of the humic acids and possibly to a minor extent also for the ionization constant and the alkoxyl and alkimide groups. It was noticed that the presence of charcoal and, to a minor extent also, of clays in decomposing plant material promoted the formation of humic acids which were very similar to those found in older peat deposits, while the presence of ash did not seem to have much effect. Humic acids derived from different peat materials were found to be very similar in structure and composition, but when different types of plant material were mixed, the humic acids formed during the first stages of decomposition were very similar to those from more decomposed samples containing only the separate components.
A PRELIMINARY STUDY OF SOME SLOPE SOILS IN WALES AND THE WELSH BORDERLAND
Authors: MACKNEY D. , BURNHAM C. P.
Published: July 2006

Data are given concerning four profiles developed in materials of loam or clay‐loam texture, representative of soils found on moderate or steep slopes in Wales and the Welsh Borderland. Two acid well‐drained soils with A(B)C profiles are correlated with sols bruns acides, differences in soluble Fe2O3 content probably being the result of more intense weathering in districts of greater rainfall. A humus‐iron podzol described differs from typical profiles of this class in being finer in texture, and there is a significant divergence in micromorphology. The remaining soil is regarded as transitional because it has some properties of both classes. It has a prominent brown B horizon of redder hue than the overlying unbleached A horizon; organic carbon values are distinctly greater than for solsbruns acides, but there is no horizon of accumulation; SiO2/R2O3 ratios follow the pattern of variation typical of podzols though differences are less marked; the micromorphological characters of the B horizon are very similar to those of the Bs horizon of the humus‐iron podzol.
A CATENA OF SOILS ON THE NORTHERN RHODESIA PLATEAU
Authors: WEBSTER R.
Published: July 2006

The plateaux of Northern Rhodesia have a characteristic pattern of soils which, with variations, covers many thousands of square miles. A representative sequence of soils ranging downslope from red, through yellowish brown to grey is described. The soils are composed of material in an advanced stage of weathering and are shown to be developed more or less in situ from biotite gneiss. Redeposition of material once eroded is relatively unimportant. The colour sequence in this instance is attributed to the proportion of free iron oxides in the soil.
SLOPE DEVELOPMENT AND SOIL MORPHOLOGY IN A PART OF SOUTH‐WEST NIGERIA
Authors: MOSS R. P.
Published: July 2006

The soils of two cuestas developed on ferruginous sandstones, one of Cretaceous, and the other of Eocene/Pliocene age, were studied in relation to the slopes and planation surfaces with which they were associated. The processes involved in the retreat of hardened plinthite breakaways are shown to account for the principal morphological features of the soils, especially the lower diagnostic horizons, and thus throw light upon the mode of formation of the ‘Acid Sands’ of southern Nigeria, and the ‘terre de barre’ of the ‘Continental Terminal’ of southern Dahomey. A distinction is made between sheet plinthites and flanking plinthites according to their mode of occurrence, both being related to periods of stillstand in the evolution of the slopes.
A SURVEY OF ACTIVITIES OF ENZYMES HYDROLYSING SUCROSE AND STARCH IN SOILS UNDER PASTURE
Authors: ROSS D. J.
Published: July 2006

Some climatic and soil factors influencing the activities of enzymes hydrolysing sucrose and starch in New Zealand soils under pasture were studied.

Amounts of reducing sugars produced on incubation of soils without added substrate were related very closely to soil organic C content.

Activities of (a) enzymes hydrolysing sucrose and (b) enzymes hydrolysing starch decreased and increased, respectively, with increasing rainfall; the ratios (a)/(i) were highest in the driest groups of soils.

Variations in annual rainfall and soil organic C together, but not separately, explained much of the variation in sucrose‐hydrolysing activities; these activities appeared to be related more to the composition than the amount of organic matter in a soil.

Variations in activity of enzymes hydrolysing starch could be explained by variations in soil organic C, clay content, and, in some cases, other factors associated with different soil groups; these activities were increased by irrigation and reduced by drainage of soils.

The activity of starch‐hydrolysing enzymes, compared with sucrose‐hydrolysing enzymes, was relatively greater under legumes than under grasses at the same site but could differ considerably at different sites. Activities also differed under forest and pasture at adjacent sites.
THE VOLUME AND POROSITY OF SOIL CRUMBS
Authors: CURRIE J. A.
Published: July 2006

A simple and inexpensive apparatus (a test‐tube, burette, and pin) is described for measuring volumes by liquid displacement to an accuracy of greater than 0.5 per cent. This has been adapted to measure soil crumb porosities, εc, by saturating 3–4 g samples of crumbs with kerosene, measuring the weight of kerosene retained internally, then measuring their volume by displacement. Three estimates of crumb porosity from these measurements are compared. Experimental values range from εc= 0.205 for the headland of an arable field to εc= 0.351 for a permanent pasture. Crumb porosity is proposed as a measure of structural status for soils because it assesses the degree to which soil management has succeeded in holding the constituent primary particles apart from the positions of inherent closest packing that they would ultimately assume in an unstable soil. By comparison, the inter‐crumb porosity, εv, can be used as a measure of cultivation status. In the form expressed, these two porosities are related to the more frequently encountered total porosity εt by the relation

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A KINETIC APPROACH TO THE DESCRIPTION OF SOIL PHOSPHATE STATUS
Authors: COOKE I. J.
Published: July 2006

A kinetic factor is used to describe soil phosphate status. It is supplementary to capacity and intensity factors which are essentially static factors.

The rate of release of phosphate ions from the soil solid phase was measured by the use of an anion exchange resin and a numerical parameter assigned to the release rate. A highly significant correlation was found between this parameter and the uptake of phosphate by ryegrass from a wide range of soils.
THE INFLUENCE OF TEXTURE ON THE MOISTURE CHARACTERISTICS OF SOILS
Authors: SALTER P. J. , BERRY G. , WILLIAMS J. B.
Published: July 2006

A quantitative assessment was made of the effect of the proportion of sand, silt, clay, and organic matter in twenty‐six soils on the available‐water capacities (AWC) of the soils. The AWC of a soil was negatively correlated with percentage coarse sand and positively correlated with the percentages of International fine sand (or American silt) and organic C. Using a regression equation, the AWC's of the soils were estimated from mechanical analysis data with a mean accuracy of ± 16 per cent of the mean AWC.
A SIMPLE AND RELIABLE TENSION TABLE
Authors: CLEMENT C. R.
Published: July 2006

A tension table may be constructed from a Perspex tray ⅝ in. thick, approximately 12 in. wide and 19 in. long with 21 drainage channels. With a filter paper membrane, which gives rapid transmission of water and can be readily changed when contaminated it may be used to equilibrate 3–4 kg of moist soil overnight at suctions up to 100 cm of water. Several small samples may be handled at once by using small filter‐paper trays.
THE MINERALOGY OF THE CLAY FRACTION FROM BASALTIC SOILS IN THE GALILEE, ISRAEL
Authors: SINGER ARIEH
Published: July 2006

The mineralogy of the clay fraction from basaltic soils in the Galilee, Israel, has been studied by X‐ray and differential thermal analysis techniques, supplemented by electron‐micrographs and chemical determinations.

The mineralogical composition of the clay was greatly influenced by the amount of rainfall. In SE Galilee, where rainfall is 400–550 mm/annum, the dominant clay mineral is montmorillonite, with kaolinite as the second most important component. With increasing rainfall the amount of montmorillonite in the clay falls, and the amount of amorphous oxides of Fe and Al increases. In N and NE Galilee, rainfall is 550–700 mm/annum and the major part of the clay is composed of kaolinite or halloysite, quartz, and amorphous oxides of Fe and Al. The decrease in the amount of montmorillonite with increasing rainfall is explained by decomposition to kaolinite and amorphous oxides.
THE MEASUREMENT AND MECHANISM OF ION DIFFUSION IN SOILS
Authors: VAIDYANATHAN L. V. , NYE P. H.
Published: July 2006

The diffusive flux of soil cations and anions to an absorbing surface may be measured by a simple, quick, and accurate method using ion exchange resin paper as a sink maintaining, initially, zero concentration of the diffusate at the soil surface.

The quantity of ions diffusing from the soil of semi‐infinite thickness is directly proportional to the square root of the diffusion time until about half the counter‐ions originally on the resin have been exchanged. Values of average effective diffusion coefficients are calculated using this proportionality constant and the concentration of total exchangeable ions. The effect of the counter‐ions of the resin on soil‐ion flux is small but measurable.
THE MECHANISM OF PHOSPHATE ADSORPTION BY KAOLINITE, GIBBSITE, AND PSEUDOBOEHMITE
Authors: MULJADI D. , POSNER A. M. , QUIRK J. P.
Published: July 2006

The adsorption isotherms (20°C) of phosphate on two potassium kaolinites and two aluminium oxides have been determined at pH values from 3 to 10 and at concentrations ranging from 10−4 to 10−2M. The reversibility of the adsorption with respect to pH and concentration has also been examined.

The isotherms result from at least three types of adsorption site (regions I, II, and III) of widely different reactivities. The number of adsorption sites increases to a limit with decrease in pH for regions I and II. The behaviour of region III is more complex.

The different adsorbents behave in essentially the same manner and differ only in the number of adsorption sites.

It is tentatively suggested that regions I and II are located on an edge –Al(OH)2 of the adsorbents, while region III results from penetration into some amorphous region of the crystal surface.