bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EFFECT OF TEMPERATURE ON THE MICROBIAL TRANSFORMATION OF [14C] GLUCOSE DURING INCUBATION IN SOIL
Authors: CHESHIRE M. V. , GREAVES M. P. , MUNDIE C. M. 
Published: July 2006

SummaryWhen two different soils were incubated after the addition of [14C] glucose in the dark at winter temperatures or at 5°C in the laboratory and then hydrolysed, radioactivity was detected in all seven common soil sugars except arabinose. In contrast, in incubations at 20°C, little radioactivity was found in the xylose. Examination of the microflora showed that the number of viable bacteria was one‐tenth at the lower temperatures, whereas the numbers of yeasts, fungi, and actinomycetes were unaffected. Analysis of cultures of representative microbial isolates showed that none of the fungi or actinomycetes and only 3 per cent of the bacteria synthesized xylose, compared with 85 per cent of the yeasts.It is concluded that when these soils are incubated at low temperatures xylose is synthesized principally by yeasts.
A MATHEMATICAL MODEL FOR THE DIFFERENTIAL MOVEMENT OF TWO SOIL CONSTITUENTS INTO ILLUVIAL HORIZONS: APPLICATION TO CLAY RATIOS IN ARGILLIC HORIZONS
Authors: VAN WAMBEKE A. 
Published: July 2006

SummaryThe effects of the migration of two soil constituents into illuvial horizons is described by a set of equations. Differential movement of clay fractions during illuviation causes changes in the fine to total clay ratios in A and B horizons.A mathematical model is used for the interpretation of clay fraction data in order to estimate the degree of profile development, the amounts of fine and total clay which have moved, and to determine the original composition of the parent material. No bulk density data of the soil horizons are necessary for the computation.The equations can be programmed on desk calculators. Comparison with measurements on Alfisols in temperate regions was found to be satisfactory.
THE TEMPERATURE OF THE SOIL UNDER A BARLEY CROP
Authors: HAY R. K. M. 
Published: July 2006

SummaryContinuous records of soil temperature were collected at 1, 5, and 20 cm depth, throughout the growing season, under crops of barley in the east of Scotland. The values obtained were considerably lower than the temperatures normally employed in laboratory studies of temperate cereal roots. The resulting hazards in extrapolating from the laboratory to the field are briefly discussed.
EFFECTS OF CALCIUM CARBONATE ON THE SWELLING BEHAVIOUR OF A SOIL CLAY
Authors: RIMMER D. L. , GREENLAND D. J. 
Published: July 2006

SummaryMeasurements of the swelling behaviour of a soil clay, in both Ca‐ and Na‐saturated forms, before and after removal of calcium carbonate have been made. For the Ca‐clays, three suctions were used, 10·0 mbar, 63·1 bar, and 1·59 kbar. There were no significant differences in the swelling before and after carbonate removal at 1·59 kbar. At 63·1 bar, removal of carbonate led to decreases in swelling for all samples. At 10 mbar suction, removal led to increases in swelling for samples initially with > 1 per cent carbonate and to decreases for samples with < 1 per cent. For the Na‐clays, only 10mbar suction was used and similar results to those for Ca‐clays were obtained, except that the swelling was greater and the differences larger. The effect of varying the electrolyte concentration on the swelling behaviour of the Na‐clays was also studied. The swelling data can be partly explained in terms of the suppression of diffuse layer formation when calcium carbonate was present. Surface area determinations before and after decalcification led to the conclusion that the carbonate was also acting as a cement. The decrease in swelling after carbonate removal, for all samples at 63·1 bar suction, and for samples initially low in carbonate at 10 mbar suction, is thought to be due to the mobilization and redeposition of hydroxy‐alumina polymers during the treatment.
SOLUBLE POLYMERIC HYDROXY‐ALUMINIUM IONS IN ACID SOILS
Authors: BACHE B. W. , SHARP G. S. 
Published: July 2006

SummarySolution concentrations of total Al and of mononuclear Al ions were determined as a function of pH for two acid soils. Polynuclear hydroxy‐Al was taken as the difference between total and mononuclear Al. Salt concentration at 1 : 5 soil: solution ratio was varied from 0·008 to 1·o equiv/l, for CaCl2, KCl, and NH4OAc at pH 4·8. Polynuclear hydroxy‐Al concentrations increased with electrolyte concentration and the valency of the desorbing cation, and rose to 0·2 mM (equivalent to 3 meq/kg soil) in unbuffered salt suspensions, and to 1·0 mM in NH4OAc at pH 4·8. Polynuclear hydroxy‐Al thus behaves like a normal exchangeable cation. I.0M NH4OAc released much more total A1 from some of the more acid samples than might have been expected from its pH of 4·8.
DECOMPOSITION OF ORGANIC MATTER ON THE FOREST FLOOR OF PINUS RADIATA PLANTATIONS
Authors: LAMB D. 
Published: July 2006

SummaryLaboratory experiments were carried out on the relative decomposition of litters collected from stands with contrasting accumulations of organic matter on the forest floor. Decomposition was measured by the weight loss of sterile litters inoculated with Pholiota and Lenzites, and by the microbial respiration in non sterile litters.Some differences were measured in litters from stands with dissimilar ages and productivities. The most striking differences in decomposition were those observed in litters from older stands (assumed to be in a steady state condition) of the same age and productivity class but on different soil types. These differences matched the patterns of relative litter accumulations in these stands in the field. The variations found in P. radiata litter decomposition were attributed to nutritionally induced differences in polyphenol complexing of litter materials.
OXYGEN UPTAKE AND RESPIRATORY QUOTIENT OF FIELD SOIL CORES IN RELATION TO THEIR AIR‐FILLED PORE SPACE
Authors: BRIDGE B. J. , RIXONZ A. J. 
Published: July 2006

SummaryThe oxygen uptake and respiratory quotient (RQ) of field cores from three soils of different texture classes were studied using electrolytic respirometers. Critical values of air‐filled pore space (f), above which RQ was always near unity, that is, corresponding to the transition from anaerobic to aerobic respiration, were defined for each soil. These critical values agreed with minimum values off required for plant growth as reported in the literature, suggesting that RQ can be used as an index of adequate soil aeration.Oxygen uptake by the three soils reached a maximum at f values slightly above the critical values, corresponding to the highest moisture content at which oxygen diffusion was non‐limiting.
EFFECT OF ARTIFICIAL WEATHERING CYCLES ON THE STRUCTURAL STABILITY OF A DISPERSED SILT SOIL
Authors: RICHARDSON S. J. 
Published: July 2006

SummaryA very fine sandy loam soil was severely puddled in the laboratory and subjected to varying numbers of freeze/thaw‐wet/dry cycles in an attempt to restore its original level of structural stability. After only three cycles the stability of the treated soil reached its maximum value, which was slightly greater than that of untreated soil collected from the field. A higher level of soil organic matter was accompanied by an increase in structural stability as determined by the dispersion ratio technique and a technique involving partial dispersion in Calgon.
ADSORPTION OF PHOSPHATE BY GIBBSITE
Authors: HELYAR K. R. , MUNNS D. N. , BURAU R. G. 
Published: July 2006

SummaryThe effects of the nitrate salts of zinc, cadmium, and strontium on the adsorption of phosphate by gibbsite have been measured at pH 5.5 and 25° C. At solution phosphate concentrations greater than 10 μM strontium and cadmium increased phosphate adsorption whilst zinc had no effect. At lower phosphate concentrations zinc and cadmium increased adsorption of phosphate in a different manner from strontium, sodium, potassium, magnesium, or calcium. Zinc and cadmium at 1 mM concentration inhibited phosphate adsorption, perhaps because they are specifically adsorbed as indicated by pH‐shift data.A postulated surface complex consists of two adjacent adsorbed phosphate ions and a central divalent cation of appropriate size, charge, and possible co‐ordinating properties.
EFFECT OF pH ON THE REACTION OF SODIUM FLUORIDE WITH HYDROUS OXIDES OF SILICON, ALUMINIUM, AND IRON, AND WITH POORLY ORDERED ALUMINOSILICATES
Authors: PERROTT K. W. , SMITH B. F. L. , MITCHELL B. D. 
Published: July 2006

SummaryThe release of hydroxyl ions from silica and ferric oxide gels on treatment with sodium fluoride solution is very small above pH values of 7.6 and 9 respectively. Hydroxyl release from alumina gel and poorly ordered aluminosilicates is appreciable at pH 9 and varies little with pH, but that from crystalline forms of alumina decreases with decrease of pH. For poorly ordered aluminosilicates, the ratio (OH′ released at pH 8.0): (OH′ released at pH 6.8) is directly proportional to the mole fraction Al/(Al+Si). The measurement of hydroxyl release at differing pH values may enable determination of hydrous alumina separately from the total poorly ordered inorganic gel material; moreover, the amount of hydroxyl released at high pH values is related to phosphate sorption capacity.
THE CATEGORIES OF ALUMINIUM‐ AND IRON‐HUMUS COMPLEXES IN ANDO SOILS DETERMINED BY SELECTIVE DISSOLUTION
Authors: WADA KOJI , HIGASHI TERUO 
Published: July 2006

SummaryThirty‐three samples of Ando soils were extracted by sodium pyrophosphate (O.IM; pH 10) and by dithionite‐citrate. The Al, Fe, and C contents of these two extracts offer a means of differentiating the status of humus in relation to Al and Fe in the different horizons. The humus that forms at first in the Al horizon has a very low complexing ability for Al and Fe and little is dissolved by pyrophosphate. The humus evolves with time or pedogenesis into forms that complex Al and Fe released from volcanic ash by weathering, and which are dissolved by pyrophosphate. In the old horizons, the humus further reacts with additional Al and Fe, some of which may be present as hydrous oxides or allophane‐like constituents, allophane and imogolite. This reaction probably makes the humus less soluble in pyrophosphate.
SOME EFFECTS OF MOUND‐BUILDING TERMITES ON SOILS IN UGANDA
Authors: POMEROY D. E. 
Published: July 2006

SummaryMost large mounds in Uganda are built by termites of the genus Macrotermes. Except for those in valley bottoms they are composed of subsoil which is thought to be collected mainly from depths of 0.5 to 1.0 m, although the evidence is inconclusive. Mounds of both M. bellicosus and M. subhyalinus contain less sand than the subsoil when this is sandy, but only M. subhyalinus mounds contain less clay when the subsoil has a high clay content. In general both species tend to produce a stone‐free topsoil whose physical properties are closer to a loam than the average subsoil. Mounds of both species in valley bottoms appear to be built from topsoil.The amounts of organic matter, nitrogen, calcium, phosphorus, and potassium in mounds were estimated together with their rates of turnover. In terms of the demands of two typical crop plants the quantities held in mounds and their rate of release to the surrounding topsoil were small. Only calcium was likely to be cycled in significant amounts.It seems that termites only slightly affect the physical and chemical properties of Ugandan soils, even where mounds are comparatively abundant.
VARIABILITY IN THREE AREAS OF THE DENCHWORTH SOIL MAP UNIT.
Authors: BASCOMB C. L. , JARVIS M. G. 
Published: July 2006

SummaryVariability of soil within three areas of the Denchworth map unit in southern England Has been investigated by describing and analysing samples from thirty profiles located at the intersects of a randomly oriented grid.The Denchworth series has been mapped over several stratigraphically different clays, and the areas chosen provide three groups of profiles developed over Gault (Cretaceous), Kimmeridge, and Oxford (Jurassic) Clay respectively.Purity of the map unit, estimated as the percentage of profiles whose data agree with the definition of the Denchworth series, was 60 per cent, which is comparable with values for other map units both near by and elsewhere.The variability of individual properties as indicated by coefficients of variation differed widely. Generally, physical properties were more uniform than chemical properties. The Denchworth map unit can consequently be treated uniformly for aspects of land management related to soil physical properties but it provides little guidance for fertilizer application.A small amount of variability can be attributed to mapping together those soils developed in material derived from stratigraphically different clays, but is insufficient to justify separating them.
TOWARDS AN ABSOLUTE MEASUREMENT OF SOIL STRUCTURAL STABILITY USING ULTRASOUND
Authors: NORTH P. F. 
Published: July 2006

SummaryCalibrations enabled controlled application of a range of known dispersive energies to a selected soil sample. The corresponding levels of dispersion were measured in terms of the weight fraction of particles <2 μm equivalent spherical diameter produced, and are used to define a dispersion characteristic for the test soil.Interpretation of this characteristic in terms of a microaggregate theory provides the energy value associated with complete ‘primary dispersion’ of microaggregates, which under normal field conditions is a direct practical measure of soil stability. This leads to a definition of the specific stability index (σ) of a soil which for the gleyed brown earth used in this work has the value (25±3) J g−1.
THE ASYMMETRIC LEACHING PATTERN OF NITRATE AND CHLORIDE IN A LOAMY SAND UNDER FIELD CONDITIONS
Authors: WILD A. , BABIKER I. A. 
Published: July 2006

SummaryIn a field experiment on a weakly structured, almost stone‐free loamy sand, the depths of leaching of chloride and nitrate were measured after sprinkler irrigation at 8 mm/h. The modal depth of movement of the two ions was about half the mean depth of movement, indicating a highly skewed distribution and a pronounced leading tail of chloride and nitrate. The marked asymmetry of the salt distribution is attributed to uneven downward movement of water, including movement down earthworm channels, which results in part of the nitrate and chloride being deeply leached.
SELECTIVE EXTRACTION OF AMORPHOUS IRON OXIDE BY EDTA FROM A MIXTURE OF AMORPHOUS IRON OXIDE, GOETHITE, AND HEMATITE
Authors: BORGGAARD O. K. 
Published: July 2006

SummaryIron (III) was extracted by EDTA and ammonium oxalate from a model substance consisting of amorphous iron oxide, goethite, and hematite precipitated in the presence of quartz sand. Even by varying the EDTA concentration between 0.02 and 0.1 M, pH between 4.40 and 6.00, the solid:solution ratio between I:25 and I:250, and using extraction times up to go days, it was found that EDTA was able to extract only a limited amount of iron. In contrast, 0.2 M ammonium oxalate at pH 3.0 is able to dissolve all the iron compounds if the extraction time is sufficient. Nevertheless, the amount of EDTA‐extractable iron is equal to the amount of iron extracted after 4–5 hours with ammonium oxalateat pH 3.0.From X‐ray analysis, DTA curves, a solubility product determination, and a kinetic investigation, it is concluded that the EDTA‐extractable fraction consists of X‐ray amorphous iron oxide, less soluble than polymeric iron hydroxide, and presumably only one compound.Therefore, it is concluded that it may be possible by means of EDTA to carry out a selective extraction of X‐ray amorphous iron oxides mixed with goethite and hematite.
THE COMPOSITION OF MOUNDS OF THE TERMITE MACROTERMES FALCIGER (GERSTACKER) ON SOIL DERIVED FROM GRANITE IN THREE RAINFALL ZONES OF RHODESIA
Authors: WATSON J. P. 
Published: July 2006

SummaryThirty‐eight termite mounds (about 1.6 m high and 7.6 m basal diameter) and the same number of adjacent soils were sampled in three rainfall zones: low (below 700 mm annual rainfall), medium (700 to 1000 mm annual rainfall), and high (above 1000 mm annual rainfall). Higher amounts of clay, silt, and fine sand, and lower amounts of coarse sand occurred in termite mounds than in adjacent soils of all rainfall zones. Extractable cations (Ca, Mg, and K), calcium carbonate, pH, electrical conductivity, and organic carbon were also higher in termite mounds than adjacent soils of all rainfall zones.Wide differences in extractable calcium between termite mounds and adjacent soils of low and medium rainfall zones indicated weak leaching of termite mounds; narrow differences in the high rainfall zone indicated strong leaching of the mounds.The ‘umbrella effect’ of termite mounds in shedding rainfall and retarding leaching is clearly displayed in the medium rainfall zone where high concentrations of extractable calcium in termite mounds and low concentrations in adjacent soils indicate weak and strong leaching respectively.
EFFECT OF SOIL pH AND ORGANIC MATTER ON LABILE ALUMINIUM IN SOILS UNDER PERMANENT GRASS
Authors: CABRERA F. , TALIBUDEEN O. 
Published: July 2006

SummaryThe rates of extraction of Na, K, Mg, Ca, and Al with 1M NH4 NO3 from the mineral‐and organic‐rich layers of some Park Grass (Rothamsted) soils were measured at the pH of the soil. Below pH 3.7 exchangeable Al, derived from the kinetics curve, increases with decreasing soil pH and is less in the organic‐rich layer. The sum of the basic exchangeable cations, ∑(Na + K + Mg + Ca), increases with increasing soil pH and is more in the organic‐rich layer.The extraction of exchangeable Al obeys first order kinetics, the rate constant being similar for all the soils (mean value 36 ± 7 × 10−6|s−1), which implies that exchangeable Al is released from surfaces with similar properties for the adsorption of Al, and that the rate is not affected by soil pH and organic matter. The rate of extraction of non‐exchangeable Al is the same in the mineral‐and organic‐rich layers of each soil, and is maximal at about pH 3.7, decreasing sharply at more and less acid pH values.
CONCENTRATIONS AND ACTIVITIES OF IONS IN SOLUTIONS DISPLACED FROM BASALTIC SOILS
Authors: BENIANS G. , SCULLION P. , FITZHUGH G. R. 
Published: July 2006

SummarySoil solutions displaced from Antrim basaltic soils were analysed for major inorganic constituents. The solutions were nearly saturated with aluminium and phosphate but not sulphate. Iron concentrations were greatly in excess of ferric hydroxide solubility. The solutions were less concentrated than those described for soils of Britain and the U.S.A., representing a leaching environment.
PEAT WASTAGE IN THE EAST ANGLIAN FENS
Authors: RICHARDSON S. J. , SMITH J. 
Published: July 2006

SummaryMeasurements of the decline in peat depth between 1941 and 1971 were taken at 14 sites across the East Anglian Fens. Rates of wastage in the period before 1955 and in the more recent period varied widely from site to site. Wastage rates were higher at all sites but one, in the period before 1955. The mean value for wastage rate over the entire period covered was 1.37 (± 0.78) cm/yr.
WEATHERING STAGES OF THE COMMON IGNEOUS ROCKS, INDEX MINERALS AND MINERAL ASSEMBLAGES AT THE SURFACE OF THE EARTH
Authors: CHESWORTH WARD 
Published: July 2006

SummaryThe system SiO2 ‐AlOOH‐Fe2 O3 ‐H2 O is used to show certain short‐comings in the use of single minerals to index weathering stages. An alternative (analogous to the metamorphic facies concept) is proposed in which three stages are recognized, one of which can already be defined in terms of mineral assemblages, while the two earlier stages should eventually prove open to this treatment.
THE MEASUREMENT AND CHARACTERISATION OF VOIDS IN SOIL THIN SECTIONS BY IMAGE ANALYSIS. PART II. APPLICATIONS
Authors: MURPHY C. P. , BULLOCK P. , BISWELL K. J. 
Published: July 2006

SummaryImage analysis was used to measure and characterise the voids in two sets of soil samples; (i) a surface water gley soil of the Deighton series and (ii) soils from a compaction experiment. The results show that the Deighton soil contains two impervious horizons separated by a much more porous horizon. In all the horizons most of the pore space is due to pores >180μm diam. In the case of the soils from the compaction experiment compaction was shown to change the shape, orientation and size distribution of the pores considerably. The range of measurements demonstrates that image analysis is applicable to several areas of soil research.
ISOTOPIC EXCHANGE OF PHOSPHATE ON SOME PHOSPHATIC COMPOUNDS
Authors: de BUSSETTI S. G. , FERREIRO E. A. , HELMY A. K. 
Published: July 2006

SummaryThe kinetics of isotopic exchange of phosphate on hydroxyapatite, amorphous aluminium phosphate, phosphate‐treated aluminium oxide and dicalcium phosphate dihydrate were studied in aqueous suspensions as a function of solid/solution ratio and amount of added isotope. The tracer exchange reaction was independent of time for the dicalcium phosphate due to a very small amount of exchangeable phosphate found in the solid and to the high solubility of the material. For the other phosphates, a power function and/or a function composed of a series of exponential terms were found suitable for representing the tracer kinetics. The theoretical background for both functions is shown to be approximately the same. Both describe tracer kinetics for a system containing more than one solid phase. The amounts of exchangeable P were found to depend strongly on the solid/solution ratio but not on the amount of radioactivity added. The dependence of the tracer kinetics on the solid/solution ratio is due to the ageing processes that give rise to the formation of surface layers having physical and chemical properties different from those of the bulk solid.
FRACTIONATION OF HUMIC ACID BY GEL PERMEATION CHROMATOGRAPHY
Authors: ANDERSON H. A. , HEPBURN A. 
Published: July 2006

SummaryHumic acids from the L layer and B2hhorizons of a humus‐iron podzol were fractionated by gel permeation chromatography. Elution of the gel column with distilled water adjusted to pH 7.5 gave a fractionation based on both gel permeation and adsorption chromatography. This procedure gave filtered products containing most of the organic nitrogen, and an absorbed fraction. The latter contained most of the components which gave benzene carboxylic acids on oxidation of the humic acid with dilute nitric acid.
SIZE FRACTIONATION, DISSOLUTION ANALYSIS, AND INFRA‐RED SPECTROSCOPY OF HUMUS COMPLEXES IN ANDO SOILS
Authors: HIGASHI TERUO , WADA KOJI 
Published: July 2006

SummaryEight samples of Ando soil A1 and buried A1 horizons of different ages were fractionated into clay‐, silt‐, and sand‐size separates, and the yields and carbon contents of these separates were determined. The clay‐size separates were subjected to two series of successive extractions, 1) 0.1 M Na4 P2 O7/2% Na2 CO3/0.5 M NaOH and 2) dithionite‐citrate/2% Na2 CO3/0.5 M NaOH; and to difference infra‐red spectroscopy for identification of the extracted constituents.The result indicated that humus evolves from forms with a very low complexing ability for Al and Fe into forms that complex Al and Fe in the A1 horizon, and that humus further interacts with allophane‐like constituents, allophane and imogolite in the buried A1 horizon. These reactions between humus and inorganic constituents result in formation of silt‐ and sand‐size aggregates which are stable to sonic wave treatment, but are broken down into finer particles upon boiling with H2 O2.