bluuebunny/crossref_metadata_2025_split huggingface dataset:
ISOTOPICALLY EXCHANGEABLE PHOSPHORUS IN SOILS
Authors: TALIBUDEEN O. 
Published: July 2006

SummaryPhosphate residues in the soil were subdivided into three fractions on the basis of isotopic exchange of orthophosphate ions between the soil and the soil solution. It was observed that the total labile phosphorus was a smaller fraction of the total phosphorus in the heavier soils (c. 20 per cent. clay) than in the lighter soils (1–10 per cent. clay), This could be partly attributed to a higher organic‐phosphorus content in the heavier soils. In comparable soils, recent manuring with superphosphate increased the ratio of the rapidly labile phosphate to the total labile phosphate; in the soils of lower clay content, this ratio was higher than the corresponding ratios in the heavier soils. The recovery of phosphorus added at a moderately heavy rate was estimated by this method of fractionation in soils incubated for periods up to 3 months after treatment. Recovery of added phosphorus in the total labile fraction was incomplete for the calcareous soils, as compared to a I00 per cent. recovery in a neutral soil of similar clay content. Moreover, a redistribution of phosphorus with time was observed in the calcareous soils within the total labile fraction, no such effect being observed with the neutral soil. This was attributed to the presence of internal surfaces on the calcium carbonate present.
THE ALKALINE NITROBENZENE OXIDATION OF SOIL ORGANIC MATTER
Authors: MORRISON R. I. 
Published: July 2006

SummaryThe 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

SummaryThe 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

SummaryThe 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

SummaryDue 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

SummaryA 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

SummaryAttention 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

SummaryTests 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

SummaryPaper 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

SummaryThe 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

SummaryFeatures 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

SummaryThe 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

SummaryThe 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

SummaryA 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.
IRON AND THE Eh OF WATERLOGGED SOILS WITH PARTICULAR REFERENCE TO PADDY
Authors: JEFFERY J. W. O. 
Published: July 2006

SummaryAssuming 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

SummaryMuch 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

SummaryOne 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

SummaryAn 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

SummaryThe 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

SummaryNatural 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.