bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE RELATION BETWEEN BULK DENSITY, AVAILABLE WATER CAPACITY, AND AIR CAPACITY OF SOILS
Authors: ARCHER J. R. , SMITH P. D. 
Published: July 2006

SummaryThe effect of bulk density on moisture content at 50 mb tension in four soils of different textures was studied. The volumetric water content increased linearly with bulk density over a wide range of densities. Depending on texture, a maximum bulk density was reached above which continued compaction decreased the water content. This is shown to be the point at which the air capacity of the soil at this tension approaches zero. Accepting that the gravimetric wilting point depends mainly on texture, the available water capacity varies in a manner similar to the 50 mb water content.If the relationships described are valid in the field, the available water capacity and air capacity may be optimized using cultivation techniques to adjust the bulk density. The available water capacity of coarse‐textured droughty soils may be increased by increasing the bulk density provided that the air capacity remains above acceptable lower limits (10–15 per cent). Conversely, the air capacity of compacted soils with large available‐water capacities could be increased by reducing the bulk density to a value corresponding to an acceptable available‐water capacity. In very compacted soils a decrease in bulk density will benefit both available‐water capacity and air capacity.
THE ORIGIN OF SOIL POLYSACCHARIDE: TRANSFORMATION OF SUGARS DURING THE DECOMPOSITION IN SOIL OF PLANT MATERIAL LABELLED WITH 14C
Authors: CHESHIRE M. V. , MUNDIE C. M. , SHEPHERD H. 
Published: July 2006

SummaryIncubation of soil with 14C‐rye straw for 448 days resulted in the evolution of about 50 per cent of the carbon of the substrate as CO2 The two main sugars of the straw, glucose and xylose, were degraded to approximately the same extent (70 per cent). The same results were obtained whether the soil was derived from granitic or basic igneous parent material.There was very little transformation of the substrate to galactose, mannose, arabinose, rhamnose, or fucose, and a much slower rate of degradation than with soil incubated with 14C‐glucose over a similar period.Hydrolysis of the soil samples by a preliminary treatment with 5 N H2SO4, before treatment with 24 N H2SO4, followed by heating with N H2SO4 did not release significantly greater amounts of sugar than treatment with 24 N H2SO4 and N H2SO4 alone. Separate analysis of the hydrolysates showed that 90 per cent of each of galactose, mannose, arabinose, xylose, rhamnose, or fucose had been extracted by 5 N H2SO4, but only 50 per cent of the glucose.Fractionation of the straw‐soil mixture after 224 days incubation showed that the specific activity of the glucose was higher in the humin fraction than in the fulvic acid, as would be expected if the remaining 14C were still in the form of unchanged plant material.This evidence that plant polysaccharide persists in soil could explain the presence of much of the xylose in the soil organic matter.
THE DISTRIBUTION OF IRON, MANGANESE, AND SCOTLAND ALUMINIUM IN SOME SOILS FROM NORTH‐EAST SCOTLAND
Authors: MOORE T. R. 
Published: July 2006

SummaryTwenty‐four soils from north‐east Scotland have been subjected to differential extraction techniques to determine the effect of hydromorphism on various Fe, Mn, and A1 fractions. There were pronounced losses of dithionite‐extractable Fe and Mn from gleyed horizons, but the 'silicate‐Fe’fraction appeared to be relatively unaffected. The oxalate‐extractable Fe and A1 fractions also decreased in response to gleying. The ratio of the oxalate‐ to dithionite‐extractable Fe fractions (Fe0/Fed) increased in gleyed horizons, presumably due to variations in the rate of ageing and crystallization of amorphous Fe oxides and hydroxides.
MINERALOGY AND RADIOISOTOPE RETENTION PROPERTIES OF A CHRONOSEQUENCE OF SOILS DEVELOPED IN BASALTS OF VICTORIA, AUSTRALIA
Authors: MOKMA D. L. , JACKSON M. L. , SYERS J. K. , GIBBONS F. R. 
Published: July 2006

SummaryThe mineralogical composition and retention properties for radioisotopes (20Sr and 137Cs) of soils developed in five basalt flows of age varying from 6000 years to about four million years occurring in western Victoria were investigated. The trend of mineral weathering has been almost exclusively to amorphous material, kaolinite‐plus‐halloysite, and chlorite, the more soluble products of weathering having been removed. The most significant changes in clay mineralogical composition with time are the progressive decrease in the Si02/Al2O3 molar ratio of the amorphous material in the clay fraction of the surface horizons, from an initial value of approximately 4 to values of approximately 2, and the progressive increase in the amount of kaolinite‐plus‐halloysite, both in the topsoil and at depth, with age of the basalt flow. The amount of kaolinite plus halloysite increases from approximately 20 per cent of the clay of soil developed in the basalt flow 6000 years old to approximately 50 per cent of that of soil in basalt about four million years old. Evidence for the presence of halloysite was obtained by electron microscopy studies. The amorphous material and chlorite contents, each of which constitutes between 20 and 50 per cent of the clay fractions, decrease concurrently with the increase in kaolinite‐plushalloysite content.Fixation of Sr by whole soil samples was controlled by the organic matter and free iron oxide contents rather than by the mineralogy of the samples. A high proportion of the added Cs was sorbed by whole soil samples. Much of the sorbed Cs was not readily replaced by CaCl, washings but was replaced in part by subsequent washing with NaCl of pH 5.3 and almost entirely by subsequent NH4Cl washings. Much of the Sr and Cs deposited on these soils by rainfall and dry fall‐out would be sorbed; the ease of replacement suggests that these elements would be available for further movement through the food chain.
SOIL CLASSIFICATION WITH PARTICULAR REFERENCE TO THE SEVENTH APPROXIMATION
Authors: MITCHELL C. W. 
Published: July 2006

SummaryThe fundamental objective of soil classification is the achievement of an agreed world–wide system of maximum usefulness to the widest possible range of users. Such a classification should be natural rather than artificial because soils are natural bodies. Further, it should be hierarchical rather than co–ordinate because hierarchies are readily comprehensible and memorable, can be constructed on the basis of a few characters, and do not need to give equal weight to all criteria used in classifying soils. They also have the advantage of closely denned, mutually exclusive classes which can still make allowance for occasional aberrant profiles or pedons.The historical development of soil classifications is discussed with particular reference to the Russian and French and especially the U.S. Dept. Agric. 7th Approximation. The latter is defended against the main criticisms that have been levelled against it. It is maintained that it has been desired by sound inductive as well as deductive reasoning, that it treats soils as polythetic individuals, that it considers pedons three–dimensionally and that it permits non–hierarchical sub–classifications. Attention is given to the more practical criticisms that there is an undue emphasis on soil moisture and temperature regimes, unknown genetic criteria and the shallower horizons, and that it handles ses‐quioxidic soils inadequately. Positive advocacy is made on the ground that the 7th Approximation will facilitate and speed soil research especially in developing countries.
CALCULATING THE ECONOMIC BENEFITS OF SOIL SURVEY
Authors: BIE S. W. , ULPH A. , BECKETT P. H. T. 
Published: July 2006

SummaryA farmer (or other users of land) achieves greatest net return by using each soil for the crop and management which gives maximum return.A soil map indicates the boundaries between soils requiring different management for optimum returns. The benefits from a soil survey increase with the ‘purity’ of the soil units as mapped.The cost of soil survey increases sharply with the ‘purity’ to be achieved. So it is necessary to recognize the stage beyond which the costs of yet more detailed soil survey are unlikely to exceed the benefits to be expected from mapping units of greater ‘purity’.This paper reports a simple algorithm for calculating the probable benefits from further soil survey to produce a map of higher ‘purity’ than so far achieved.
MINERALOGY AND MORPHOLOGY OF SALT EFFLORESCENCES ON SALINE SOILS IN THE GREAT KONYA BASIN, TURKEY
Authors: DRIESSEN P. M. , SCHOORL R. 
Published: July 2006

SummarySamples from fifteen salt crusts from the central Great Konya Basin, Turkey, were studied in the laboratory. Chemical analyses data were combined with the results of X‐ray diffraction.In the mineralogical systems studied, three types of salt efflorescences of different morphology were distinguished, with mirabilite/thenardite, bloedite, and bloedite/epsomite/halite as major mineral associations. These crusts seal the surface soil more or less effectively, thus reducing evaporation and thereby preventing cracking of the saturated soils. The effectiveness of this sealing depends on the morphology of the accumulated salt minerals rather than on their chemical composition. Reclamation of salt‐encrusted spots therefore requires understanding of the mineralogy and the morphology of the efflorescent salts.
LATERITIC DEEP WEATHERING OF GRANITE
Authors: GILKES R. J. , SCHOLZ G. , DIMMOCK G. M. 
Published: July 2006

SummaryChemical and mineralogical analyses of two representative laterite profiles developed from granite in south‐western Australia have shown that several depth zones defined by particular mineral suites and geochemistry may be recognized. These zones are not simply related to the conventional morphological pallid, mottled, and ferruginous zones.Changes in geochemistry in both profiles can be related to the stability of the major mineral species and to the common isomorphous substitutions occurring in them. Ca, Na, and Mg, which are mainly present in plagioclase feldspars and ferromagnesian minerals, are removed during the earliest stage of alteration of the parent granite. K, Mn, Zn, and residual Ca, Na, Mg, and Sr decrease as microcline and micas alter to kaolin. Al and Fe are most abundant in the surface zones which contain secondary sesquioxide minerals.
THE UNIQUENESS OF THE MOISTURE CHARACTERISTICS
Authors: POULOVASSILIS A. 
Published: July 2006

SummaryExperiments, designed to test the non‐uniqueness which has been reported in the relationship between moisture content and suction in porous materials during transient flow conditions, are escribed. When a vertical column of sand was brought to uniform moisture content and uniform suction in a draining condition by percolating a constant flow through it until apparent equilibrium conditions ensued and then placed horizontally at the same time as the flow was stopped, the suction was found to decrease with time over a period of a day, indicating that the sand was now wetting up. This decrease was smaller the drier the sand. However, when the column was left in a vertical position with the water percolating through it for three hours after apparent equilibrium conditions were reached, a small adjustment of moisture content and suction was observed; when it was then placed horizontally as in the previous experiments little decrease of suction was observed. No change in suction was observed in either case if the equilibrium condition was reached in a wetting porous material.These experimental results and those of previous workers are explained by the hypothesis that, during drainage, some water is left in pores from which the air‐water interface has already retreated to drain through film flow, more slowly, subsequently to the continuous water body.Additional experiments showed that the release of entrapped air may have a small effect on the uniqueness of the moisture characteristics.
TRANSFORMATION OF SUGARS WHEN RYE HEMICELLULOSE LABELLED WITH 14C DECOMPOSES IN SOIL
Authors: CHESHIRE M. V. , MUNDIE C. M. , SHEPHERD H. 
Published: July 2006

SummaryIncubation of soil with 14C hemicellulose from rye straw for 448 days resulted in the evolution of about 70 per cent of the substrate as CO2. The two major sugar components of the hemicellulose, xylose (50 per cent) and arabinose (5 per cent), were almost completely decomposed. After 56 days only 5 per cent of the xylose remained and after 448 days only 1‐2 per cent. Similar results were obtained for soil derived from either granitic or basic igneous parent material.Almost 4 per cent of the hemicellulose was transformed to glucose and I per cent to mannose during the first 14 days of incubation.Fine grinding of 14C rye straw increased the extent of its decomposition on incubation but after 448 days 20 per cent of both its xylose and arabinose remained.It is suggested that the isolated hemicellulose is decomposed faster because it has been made water soluble.
ETHYLENE GLYCOL SORPTION BY HOMOIONIC MONTMORILLONITES
Authors: ELTANTAWy I. M. , ARNOLD P. W. 
Published: July 2006

SummaryExperimental procedures giving complete unimolecular surface coverage of montmorillonite by ethylene glycol (EG) are described. The EG sorption data, excluding rate effects, are independent of the nature of the exchangeable cations associated with the clay surfaces. The amount of EG sorbed (0.357±0.007 g EG/g montmorillonite) is larger than that obtained following previously recommended techniques based on low pressure equilibration with CaCl2‐EG mixtures (solvates) of relatively small EG content or on dynamic approaches. In both of the latter, the extent of EG sorption is determined by the exchangeable cation‐EG interaction and not by the real extent of the surface. Na‐ and K‐saturated montmorillonite‐EG complexes are less stable than those formed from Ca or Mg clay.
MICRO‐STRUCTURAL DIFFERENCES BETWEEN ARABLE AND OLD GRASSLAND SOILS AS SHOWN IN THE SCANNING ELECTRON MICROSCOPE
Authors: LOW A. J. , STUART P. R. 
Published: July 2006

SummaryThe scanning electron microscope has been used to compare the microstructure of an old grassland soil with that of an arable soil of the same soil series. The micrographs give more direct evidence than previously available of the presence of an adherent, presumably organic, matrix binding the clay and other particles of the old grassland soil. Fungal hyphae were also observed. Neither of these features was present to the same extent in the old arable soil.
A LANGMUIR TWO‐SURFACE EQUATION AS A MODEL FOR PHOSPHATE ADSORPTION BY SOILS
Authors: HOLFORD I. C. R. , WEDDERBURN R. W. M. , MATTINGLY G. E. G. 
Published: July 2006

SummaryFor forty‐one soils (pH > 5.0) from southern England and eastern Australia, the Langmuir equation was an excellent model for describing P adsorption from solutions < 10‐3M P, if it was assumed that adsorption occurs on two types of surface of contrasting bonding energies. For most of these soils, which were relatively undersaturated with P, this equation may be written as:
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where x = adsorption, k = adsorption/desorption equilibrium constant, xm= monolayer adsorption capacity, and c = equilibrium solution concentration. The relative magnitude of the parameters for each surface were approximately: xm= 0.3 x″m=0.3 and k′= 100 k. More than 90 per cent of the native adsorbed P occurs on the high‐energy surface in most soils.
DECOMPOSITION OF SOIL POLYSACCHARIDE
Authors: CHESHIRE M. V. , GREAVES M. P. , MUNDIE C. M. 
Published: July 2006

SummaryPolysaccharide material was isolated by absorption on charcoal from the acidified, non‐humic fraction extracted by alkali from three soils. The polysaccharides were used as substrates in soil incubation, perfusion, and suspension experiments. Concordant results were obtained with freely drained Countess‐wells and Insch Association soils derived from acidic and basic igneous parent materials respectively. Polysaccharide material added to soil at low concentration (I per cent) was apparently totally decomposed after 8 weeks when the amounts of polysaccharide in control and amended soils were statistically indistinguishable. At higher concentrations (2‐3 per cent) a significant difference in reducing sugar, equivalent to about 30 per cent of the substrate, remained after 32 weeks. Partial neutralization of the polysaccharide material with calcium hydroxide increased the rate of decomposition in Countesswells Association soil but had an opposite, smaller effect in Insch Association soil. Soil polysaccharide material was decomposed slightly faster in perfusion and suspension experiments than in moist soil. Only 20 per cent of the carbohydrate in the unfractionated alkali–soluble organic matter of soil was decomposed during incubation in soil for up to 133 weeks. There was usually little change in the carbohydrate content of soil incubated alone. The soil microbial population showed a marked increase in response to added polysaccharide material but only slight qualitative changes were detected.It is concluded that the persistence of naturally occurring polysaccharide in soil is related to inaccessibility caused by chemical combination, complexing or insolubility but not to a biologically‐stable molecular structure.
SANDSTONE‐DERIVED SOILS OF A CATENA AT IPERU, NIGERIA
Authors: OGUNWALE J. A. , ASHAYE T. I. 
Published: July 2006

SummaryChemical and mineralogical properties of five soil profiles of a catena in Iperu, Western State of Nigeria, are reported. The pH values of the subsoils are extremely acid. Acidity decreases with improved drainage in the subsoils (pH 4.0–5.8). The cation exchange capacity (C.E.C.) of the soils range from 3.0 to 16.2 me/100g of soil.The silt: silt+clay ratio, calcium: magnesium ratio and Fe2O3:Al2O3 ratio are used as weathering indices. The low values of the silt: silt + clay index indicate that the soils must have undergone advanced weathering. The magnitude of the Ca: Mg ratio indicates that more calcium than magnesium is available in the soils. The values for sodium and potassium are extremely low. More iron than aluminium was extracted from the soils by the dithionite‐citrate method.Kaolinite is the most abundant clay mineral. Halloysite, interstratified clay materials, vermiculite, quartz, and mica are present in considerable amounts. The silt fraction in which quartz is the most abundant mineral, also contain some kaolinite and mica.
TYPES OF SOIL DEGRADATION ON LOESS NEAR KRAKOW
Authors: KORELESKI K. 
Published: July 2006

SummaryHumus content, thickness of the accumulation horizon, soil texture, and depth of decalcification are all related to the slope of the soil surface in loess soils near Kraków.For example, humus content declines from 75 to 65 tonnes/ha as slope increases from 2 to 12°. Depth of decalcification which is about IOO cm on soils with slopes less than 2° is only about 50 cm on slopes of 12°.Such observations may prove helpful in the evaluation of the intensity of soil erosion processes on other loess areas physiographically similar to the region near Kraków.
THE INFLUENCE OF PYRITE OXIDATION PRODUCTS ON THE ADSORPTION OF PHOSPHATE BY COAL‐MINE WASTE
Authors: PULFORD I. D. , DUNCAN H. J. 
Published: July 2006

SummaryLoss of fertilizer phosphate by adsorption on coal‐mine waste can increase the cost of reclamation schemes. Samples were taken from four typical coal‐mine tips in Central Scotland and the relationships between phosphate adsorption, Tamm A1 and Fe, pH, fraction less than 2 mm, and acetic soluble calcium and sulphate were studied. Only Tamm Fe was shown to be correlated with phosphate adsorption.Unburned (black) shale adsorbed more phosphate than burned (red) shale.Heat has also been shown to influence the levels of Tamm Fe and phosphate adsorption. This is of practical significance as high temperatures can be generated within the tips as a result of spontaneous burning of the waste material.
A QUANTITATIVE ANALYSIS OF THE FACTORS AFFECTING PLANT NUTRIENT UPTAKE FROM SOME SOILS
Authors: BALDWIN J. P. 
Published: July 2006

SummaryA model of solute uptake by a growing root system is discussed in relation to the ability of a soil to support the nutritional requirements of plants. It is quantitative, and should apply to the absorption of nitrate, phosphate, and potassium by grasses and arable crops. The principles, if not the detail, are relevant to all soils.The model was tested in an experiment in which the nitrogen and potassium taken up by a rape plant were measured. The results suggest that the model has identified the significant variables in the absorption process.The principal factors affecting the supply of nutrient to a given plant are the total quantity of diffusible nutrient, the rate at which the nutrient can move, and the distance it has to travel to a root surface. The exact relevance of each factor for the different nutrients is readily determined.The diffusion coefficients of potassium and phosphate are often low. Mass flow contributes little to their supply, and an adequate exploitation of the soil reserves depends on a well‐developed root system. Nitrate, on the other hand, can usually move easily to roots, either by diffusion or mass flow. The whole rooting volume is depleted fairly quickly, and the amount absorbed depends solely on the quantity present in the rooting volume.These ideas have practical significance. In particular, they suggest that the soil properties which influence root growth may deserve as much attention as soil chemical composition in the drawing up of fertilizer recommendations.
QUANTITATIVE PEDOLOGICAL STUDIES ON SOILS DERIVED FROM SILURIAN MUDSTONES
Authors: EVANS L. J. , ADAMS W. A. 
Published: July 2006

SummaryThe uniformity of the parent material between and within five soil profiles representing a typical catenary sequence in upland mid‐Wales was investigated using as criteria of uniformity the constancy of the ratios Zr: Sr and quartz: illite in the silt fractions. No lithologic breaks could be detected in the soil profiles. ZrO2, TiO2, quartz, and tri‐acid residue were assessed for use as internal standards. TiO2 appeared to be mobile during pedogenesis. Of the other three standards tri‐acid residue was considered to be most suitable.
THE REACTION OF FLUORIDE WITH SOILS AND SOIL MINERALS
Authors: PERROTT K. W. , SMITH B. F. L. , INKSON R. H. E. 
Published: July 2006

SummaryThe reaction of sodium fluoride solution with soils and soil minerals at constant pH has been assessed as a possible single‐value characteristic in the classification of soils, particularly those containing significant amounts of poorly ordered inorganic material. A suitable method involves reaction of the soil or clay at 25°C with 0·85 M sodium fluoride at pH 6·8, the amount of OH− released after 25 min being taken as the single‐value characteristic.There was a statistically significant correlation between the amount of OH− released and the amount of alumina extracted with cold 5 per cent sodium carbonate solution from both freely drained and poorly drained Scottish soils. The multiple correlation coefficients were improved for freely drained soils by including the dithionite‐extracted ferric oxide and the silica soluble in 5 per cent sodium carbonate solution. The procedure is not suitable for surface soils, because of interference by organic matter, or for carbonate‐containing soils unless carbonate is removed.