bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECT OF PLOUGHING AND DIRECT DRILLING ON SOIL NITRATE CONTENT
Authors: DOWDELL R. J. , CANNELL R. Q. 
Published: July 2006

SummaryThe concentration of nitrate‐N at 30 cm depth in a clay soil was 2–5 times greater (p<.05) after ploughing than after direct drilling during the winter and spring of 1972–3. However, by early May no significant differences could be detected between cultivation treatments. It is concluded that decreased mineralization of soil nitrogen in the direct‐drilled soil is the main factor responsible for the differences observed.
GRAPHICAL REPRESENTATION OF TRICATIONIC EXCHANGES WHERE ONE OF THE CATIONS IS THE PROTON
Authors: ANDRÉ J. P. 
Published: July 2006

SummaryMost constituents of the adsorbing complex of the soil are cationic exchangers with variable exchange capacity: it is possible to study graphically exchanges involving the protons and two other cations. The representation developed here uses and generalizes the principle of the bicationic exchange isotherms in a square diagram. This helps to explain some experimental phenomena and enables the final equilibria of the exchange reactions to be forecast. The model seems useful for application in agronomy and physiology.
STORING AND PROCESSING DATA FOR SOIL AND LAND USE CAPABILITY SURVEYS1
Authors: RUDEFORTH C. C. 
Published: July 2006

SummaryComputer methods currently used at Aberystwyth for handling the many observations of soil and site during survey are described. While complex statistical analysis of the data is possible, the emphasis in this paper is on automatic sorting according to existing classifications and land–use, assessing the contents of map–units, and producing automatic dot distribution maps from grid data.Changes in class limits are easily made to give alternative maps. This is illustrated by land–use capability maps of Pembrokeshire.A feedback technique allows identification of sites like those growing particular crops or crop combinations, so that maps of potential crop land are produced. Provisional maps of potential barley and early potato land in Pembrokeshire illustrate the technique. Questions of computing strategy and the relevance of economic conditions are discussed.
REACTIONS RESPONSIBLE FOR HIGH pH OF Na‐SATURATED SOILS AND CLAYS
Authors: CRUZ‐ROMERO G. , COLEMAN N. T. 
Published: July 2006

SummaryHydrolysis, defined as double decomposition between Na‐adsorbent and water, occurred to extremely limited extent in suspensions of Na or Na‐Ca smectites, soil, or Dowex‐50. High pH, near 10 or above, occurred only when CaCO3 was present. Concentrations of Na were from 1–5 me/l in systems containing CaCO3, With Na or Na‐Ca Dowex‐5o and CaCO3, in CO2‐free water or NaCl solution, pH and concentrations of Na in solution‐phase were predictable from Na‐Ca exchange coefficients, CaCO3, solubility product, and ionization constants of H2CO3.
PHOSPHATE ADSORPTION AND THE DISPLACEMENT OF STRUCTURAL SILICON IN AN ALLOPHANE CLAY
Authors: RAJAN S. S. S. 
Published: July 2006

SummaryPhosphate was adsorbed at a constant pH, on allophane clay samples which had been pre‐treated with selenite to remove adsorbed silicate. The concomitant release of selenium, silicon, and hydroxyl ion on phosphate adsorption was also measured. The results are compared with those obtained from a similar experiment conducted using clay which had not been treated and they substantiate the earlier conclusion that phosphate displaces structural silicon of clays. The amount displaced increases parabolically with increasing levels of phosphate adsorbed over the concentration range studied.
PHOSPHATE ADSORPTION BY SYNTHETIC AMORPHOUS ALUMINOSILICATES
Authors: RAJAN S. S. S. , PERROTT K. W. 
Published: July 2006

SummaryPhosphate adsorption isotherms were determined for four synthetic amorphous aluminosilicate gels with A1: A1 + Si molar ratios of 0.29 to 0.88. The concomitant silicate release and acid consumed to maintain the pH of the suspensions constant were also measured.The adsorption isotherms were analysed applying a two‐term Langmuir equation–assuming two types of sites. The experimental points fitted the predicted adsorption curves only up to a certain amount of phosphate adsorbed. The deviation at high phosphate adsorption values suggested the presence of more than two types of adsorption site.A comparison of phosphate adsorbed with the silicate released and acid consumed to maintain the pH constant indicated that, for a 3 h reaction time at concentrations below about 10 μmol cm−3, phosphate exchanges mainly with aquo and hydroxo ligands and with adsorbed silicate. At higher concentrations phosphate is adsorbed (i) on sites arising from the disruption of hydroxy aluminium polymers in the gels and (ii) by the displacement of structural silicate.
PRINCIPAL KINDS OF CHRONOSEQUENCES AND THEIR SIGNIFICANCE IN SOIL HISTORY
Authors: VREEKEN W. J. 
Published: July 2006

SummaryThere are four principal kinds of chronosequences of soils that differ in age. These sequences have different combinations of isochrony and/or time‐transgression of incipience and cessation of development of their encompassed soil members. A further criterion is the presence or absence of partial overlap in the history of these members.Post‐incisive sequences have been commonly used for inferences on pathways and rates of development of individual soils, but their usual interpretation relies on the assumption that all soils involved developed the same way even while some of them may be polygenetic. Theoretically, pre‐incisive sequences are to be preferred because they should provide time‐lapse information on soil development. But, since they necessarily involve buried soils, problems of post‐burial change may complicate their interpretation. The usefulness of fully time‐transgressive sequences with partially overlapping soil tory depends on their predominant pre‐incisive or post‐incisive character. Fully time‐transgressive chronosequences without overlap of soil history may provide insight into regimes of soil development throughout geologic time, but not into rates of change of individual soils. Functional soil‐landscape units, such as catenas and valley basins may have internal soil age differentiation. This imposes restrictions on the systematic investigation of their evolution.
A NEW METHOD FOR ESTIMATING THE PHOSPHOLIPID CONTENT OF SOILS
Authors: BAKER R. T. 
Published: July 2006

SummaryA simple and effective procedure for estimating soil phospholipids is described. The method uses Soxhlet extraction with (i) ethanol plus benzene (1:4 by volume) followed by (ii) methanol plus chloroform (1:1 by volume).The method compared favourably with the standard procedure of Hance and Anderson (1963) with the advantage that no acid pre‐treatment of the soil was required.
CADMIUM ADSORPTION BY SOILS
Authors: LEVI‐MINZI R. , SOLDATINI G. F. , RIFFALDI R. 
Published: July 2006

SummaryThe Langmuir adsorption equation was found to describe Cd adsorption from dilute solutions at 5°C and 25°C for ten soils from Tuscany. The calculated Langmuir adsorption maxima (Q) and bonding energy coefficients (K) were well correlated with CEC and organic matter content.On the basis of the temperature effect on Q and K, the mechanism of Cd adsorption is discussed.
KINETICS OF ION EXCHANGE IN SOIL ORGANIC MATTER. IV. ADSORPTION AND DESORPTION OF Pb2+, Cu2+, Cd2+, Zn2+ AND Ca2+ BY PEAT
Authors: BUNZL K. , SCHMIDT W. , SANSONI B. 
Published: July 2006

SummaryThe equilibria as well as the rates of adsorption and desorption of the ions Pb2+, Cu2+, Cd2+, Zn2+, and Ca2+ by soil organic matter were determined in batch experiments as a function of the amount of metal ions added to an aqueous suspension of HCl‐washed peat. Simultaneous determination of the metal ions and hydrogen ions in the solution by atomic absorption spectrophotometry and pH‐measurements showed that the adsorption of one divalent metal ion by peat was coupled with the release of two hydrogen ions. Since this equivalent ion‐exchange process causes a corresponding increase of the electric conductivity of the solution, the rates of the adsorption and desorption processes were determined by an immersed conductivity electrode.The distribution coefficients show that the selective order for the metal adsorption by peat is Pb2+ > Cu2+ > Cd2+≌ Zn2+ > Ca2+ in the pH range of 3·5 to 4·5. The slope of ‐2, as observed in a double logarithmic plot of the distribution coefficients versus the total solution concentration confirms the equivalence of the ion‐exchange process of divalent metal ions for monovalent H3O+ ‐ions in peat. The absolute rates of adsorption, as well as the rates for the fractional attainment of the equilibrium, increase with increasing amounts of metal ions added. This behaviour is also observed for the subsequent desorption of the metal ions by H3O+‐ions. At a given amount of metal ions added, the absolute rates of adsorption decrease in the order Pb2+ > Cu2+ > Cd2+ > Zn2+ > Ca2+, while the rates for the fractional attainment of the equilibrium decrease in the order Ca2+ > Zn2+≌ Cd2+ > Pb2+ > Cu2+. The half times for adsorption and desorption were in the range of 5 to 15 sec.
INFLUENCE OF SOIL PROPERTIES ON ADSORPTION OF PESTICIDE‐DERIVED ANILINE AND p‐CHLOROANILINE
Authors: MOREALE A. , VAN BLADEL R. 
Published: July 2006

SummarySoil properties were significantly related to the adsorption of aniline and p‐chloroaniline, greater adsorption always occurring with p‐chloroaniline. Multiple regression analysis indicated that the organic matter plus available water (or clay) was better than the simple linear relationship, with organic matter alone. The resulting equations accounted for most of the variability in aniline or p‐chloroaniline adsorbed (R2= 0·92 and 0·94, respectively). The contribution of organic matter to the adsorption was calculated as 79 and 77 per cent for aniline and p‐chloroaniline.Experimental data on partially oxidized soils emphasized the major role played by soil organic matter. The variability in adsorption was mainly due to the organic matter left after oxidation (R2= 0·72 and 0·64 for aniline and p‐chloroaniline). No other combinations of variables significantly improved these relationships.
A TITANIUM‐RICH SOIL CLAY
Authors: BAIN D. C. 
Published: July 2006

SummaryA peaty podzol developed on glacial drift derived from chlorite‐schists near Loch Awe, Argyll, contains up to 25 per cent titanium dioxide in the clay fractions after removal of organic matter and free iron oxides. Electron microscopy reveals that this titanium is almost entirely in the form of cryptocrystalline anatase which is amorphous to X‐rays and which is removed by the HF method normally used to concentrate anatase and rutile in soils. The anatase has probably formed as a result of the weathering of sphene.
RECONNAISSANCE FOR SOIL SURVEY. II. PRE‐SURVEY ESTIMATES OF THE INTRICACY OF THE SOIL PATTERN
Authors: BECKETT P. H. T. , BIE S. W. 
Published: July 2006

SummaryThe best procedure for mapping the soils of an area, and the effort this will require, depend upon the intricacy of its soil pattern.This paper presents one way of describing such intricacy‐by a graph of variance against area sampled‐and an exploratory attempt to determine its form for OM, N, coarse and fine sand, silt, clay, gravel, available P and K, CEC, exch. Ca, Mg and K, in areas in the Northern Territory of Australia. This confirmed that there are considerable differences between the graphs for different properties and that areas differ very much in the short‐ and long‐range contributions to the total variability of their soil. It demonstrated the inevitable sampling problems in determining the form of variance‐area graphs.
CHANGES IN THE STRUCTURE OF MARSH SOILS FOLLOWING DRAINAGE AND ARABLE CULTIVATION
Authors: Dent D. L. , Downing E. J. B. , Rogaar H. 
Published: July 2006

SummaryMeasurements of apparent density (dry bulk density) have been used to monitor structural change in gleyed alluvial soils in Norfolk following drainage and cultivation. In Waveney series silty clay loam, drained for 9 years, soil ripening has been the dominant pedological process. Apparent density has increased throughout the drained profile due to loss of water and consequent structural rearrangement. In silty clay loam alluvium, reclaimed from the Wash over a 120‐year period, soil ripening appears to be terminated after 40 years but, under continuous arable use, apparent density continues to increase in, and immediately below, the plough layer. This increase in density is accompanied by a decline in the organic‐matter content of the plough layer.
SULPHUR, CARBON, AND NITROGEN CONTENTS OF ORGANIC FRACTIONS FROM ACETYLACETONE EXTRACTS OF SOILS
Authors: SCOTT N. M. , ANDERSON G. 
Published: July 2006

SummaryUltrasonic dispersion of acid‐pretreated soils in aqueous acetylacetone at pH 8, and at a solvent: soil ratio of about 45: I, extracted from 61 to 97 per cent of the organic sulphur from five Scottish soils. Narrowing the ratio to about 9:1 reduced the proportion extracted but was more convenient for the subsequent isolation of the organic components. Gel permeation chromatography of the extracts yielded materials containing from 14 to 60 per cent of the soil organic sulphur. Most of the soils gave four distinct fractions which contained from 21 to 38 per cent carbon, 0.2 to 2.1 per cent nitrogen, and 0.1 to 0.8 per cent sulphur. There was no consistent similarity between corresponding fractions of the various soils. Considerable amounts of iron and aluminium were extracted, presumably incorporated in organic complexes. Since they were obtained under very mild conditions, the fractions should provide useful starting materials for qualitative investigations on the nature of soil organic sulphur.
THE OCCURRENCE OF COPPER‐PORPHYRIN COMPLEXES IN SOIL HUMIC ACIDS
Authors: GOODMAN B. A. , CHESHIRE M. V. 
Published: July 2006

SummaryElectron paramagnetic resonance (e.p.r.) spectroscopy has been used to show that humic acids, which were isolated from a range of soils and from which most of the iron was removed by boiling with hydrochloric acid, contain copper in the form of porphyrin complexes. The amounts of porphyrin‐bound copper in the acid‐boiled humic acids were estimated to be ≤ 20 mg/kg (equivalent to 0.05‐0.9 mg/kg in the soils). The acid‐boiled humic acids from cultivated mineral soils showed no great capacity for further uptake of copper as copper porphyrin when treated with CuSO4, most of this additional copper being held by groups not involving N‐donor groups. In contrast, copper treatment of the acid‐boiled humic acid from a raised bog peat produced a large increase in copper‐porphyrin signal strength, indicating that in the peat there are considerable amounts of porphyrin by which added copper could be complexed. It is suggested that porphyrin groups may be involved in the fixation of copper by organic matter in soils.
THE PEDOGENESIS OF SOME GIBBSITIC SOILS FROM THE SOUTHERN UPLANDS OF SCOTLAND
Authors: WILSON M. J. , BOWN C. J. 
Published: July 2006

SummaryThe mineralogy of ten profiles developed from hornfelsic rocks on the summit areas of the Merrick and Kells Hills has been investigated by X‐ray powder diffraction, thermal, infra‐red, and optical methods.The soil clays of the C horizons of all profiles contain 6 to 37 per cent of gibbsite but this mineral is not found in the A horizons. Optical observations reveal that gibbsite is associated with hematitic rock fragments which are considered to represent older soil material–i.e. are pedorelicts. It is suggested that the Merrick soils are polygenetic and consist of two soil stratigraphic units, recent pedogenic effects being superimposed on a basal horizon that has been strongly influenced by preglacial or interglacial weathering.
THE IDENTIFICATION OF A BURIED PALEOSOL DEVELOPED IN PLACE AT PITSTONE, BUCKINGHAMSHIRE
Authors: VALENTINE K. W. G. , DALRYMPLE J. B. 
Published: July 2006

SummaryA small scarp foot valley cut in blocky Coombe rock contained three layers of calcareous material which had been washed into it, the middle one of which was soil material. Mineralogical analyses showed that there was a lithological discontinuity immediately beneath the soil material but not above it. It seemed possible that there had been a complete inversion of soil horizons by successive erosion phases upslope and deposition in the valley bottom.Micromorphological analyses showed that the particular arrangement of soil fabric in three profiles due to decalcification, gleying, and the reorganization of clay plasma varied logically according to slope position and inferred water regimes. The soil, although thin, had been developed in place. Charcoal flakes from the soil gave a radiocarbon date of 3910±220 years BP. The material that buried the soil is a combination of slopewash and ploughwash initiated by man's clearance and cultivation of the land begun in the late Neolithic or early Bronze Age.
IMPROVING A RECONNAISSANCE SOIL CLASSIFICATION BY MULTIVARIATE METHODS
Authors: BURROUGH P. A. , WEBSTER R. 
Published: July 2006

SummaryAn initial reconnaissance classification was difficult to use in soil survey in south‐west Sabah, East Malaysia, because the most commonly occurring classes of soil (subdivisions of Orthic Acrisols in the FAO/UNESCO Soil Map of the World Legend) could not be distinguished consistently. Principal component, similarity, and canonical variate analyses showed that the classes that were originally thought to be desirable overlapped almost completely with respect to profile characters and chemical properties determined by routine analysis. New guidelines for classification were devised, and class overlap was minimized by reallocating profiles using multiple discriminant analysis. The final classification of the Orthic Acrisols represented a gradation from profiles containing fresh rock fragments and weatherable minerals to those containing none. Some of the last occurred on strongly pre‐weathered sandstone; elsewhere they provided the main evidence for the remnants of a Pliocene land surface. To use the new classification consistently, estimates of total magnesium, potassium and phosphorus had to be included in routine chemical analyses. The revised classification was used successfully in subsequent reconnaissance survey work in south‐west Sabah.
MAGNETIC SUSCEPTIBILITY OF THE SOIL AND ITS SIGNIFICANCE IN SOIL SCIENCE – A REVIEW
Authors: MULLINS C. E. 
Published: July 2006

SummaryThe magnetic susceptibility of soil minerals is discussed, and in particular that of the ferrimagnetic minerals, maghemite, magnetite, and the titanomagnetites since one or more of these usually dominates soil magnetic properties. The magnetic susceptibility of soil depends on the shape, size, and concentration of these minerals as well as on the method of measurement. Measurements performed in a weak alternating magnetic field are the most reliable.The identification, formation, and occurrence of soil maghemite is considered in detail since it is usually of pedogenic origin and occurs in (magnetically) detectable amounts in most soils. Moderate concentrations (>1 per cent) of magnetite or titanomagnetite in soils may be accurately measured if some of the material is first magnetically separated and its susceptibility determined. An example is given of the use of susceptibility measurements. Pedogenic maghemite may be determined in soils developed from parent materials of low susceptibility. A very rough value of 8.8 × 10−4 m3 kg−1 is suggested for the mass susceptibility of such maghemite (excluding magnetic concretions).Although susceptibility has been suggested as an indicator of soil forming processes, this is only possible within an area containing fairly uniform parent material.
COMPUTER SIMULATION OF LOSS OF FERTILIZER NITROGEN THROUGH CHEMICAL DECOMPOSITION OF NITRITE
Authors: LAUDELOUT H. , GERMAIN L. , CHABALIER P. F. , CHIANG C. N. 
Published: July 2006

SummaryAn estimate is given of nitrogen losses which could occur through chemical decomposition of nitrite formed by nitrification of ammonium in acid tropical soils. Experiments on the rate of disappearance of nitrite were carried out in acid buffers as well as in soil samples. Numerical solutions of a system of differential equations describe the nitrification process and the chemical denitrification reaction. Up to 50 per cent of added ammonium nitrogen may be lost in an acid soil when nitrification occurs at temperatures prevailing in the humid tropics.
A COMPARISON OF THE POLYCARBOXYLIC ACIDS EXTRACTED BY WATER FROM AN AGRICULTURAL TOP SOIL WITH THOSE EXTRACTED BY ALKALI
Authors: LINEHAN D. J. 
Published: July 2006

SummaryHumic and fulvic acids were isolated from an agricultural soil by conventional means. The same soil was extracted with water and the organic matter freed of inorganic and low molecular weight substances. The usual chemical differences between humic acid and fulvic acid were confirmed and the water extract was shown to resemble fulvic acid quite closely. Further fractionation of the fulvic acid and water extract showed that the elemental composition, carboxyl and acidic hydroxyl contents, molecular weights, and infrared spectra of the purified polycarboxylic acids were virtually identical. Both promoted the same growth response in cultured isolated tomato roots.It is suggested that the qualitative similarity of fulvic acid to the polycarboxylic acid extracted by water justifies the use of the more easily isolated fulvic acid in physiological experiments on the direct effects on plants of soil organic matter.
STUDIES ON THE DECOMPOSITION OF PLANT MATERIAL IN SOIL. V. THE EFFECTS OF PLANT COVER AND SOIL TYPE ON THE LOSS OF CARBON FROM14C LABELLED RYEGRASS DECOMPOSING UNDER FIELD CONDITIONS
Authors: JENKINSON D. S. 
Published: July 2006

SummaryRyegrass uniformly labelled with 1
4C was allowed to decompose for 10 years under field conditions in a range of contrasting soils. The amount of organic matter already in a soil had no effect on the retention of labelled C by that soil, nor had a variation in soil pH of from 4.9 to 8.1. Decomposition was initially slower in a strongly acid soil (pH 3.7) but by the end of 5 years the difference between this soil and the others had almost disappeared. The more clay in a soil, the greater the retention of labelled C over the whole 10 year period; this was true of both strongly acid and near‐neutral soils. More labelled organic matter was leached from a soil containing 7.6% clay than from one with 17.5% clay, but the amount thus lost was insufficient to account for the difference in retention of C by the two soils. The decomposition of labelled plant material was faster in bare soil than in soil growing grass but the ‘protection’ thus given to the labelled C by the growing grass ended when the grass was removed.In bare soil about one third of the labelled ryegrass C was left after one year but thereafter decomposition became very much slower and about one eighth of the labelled C still remained in the soil after 10 years. The decay curve can be represented by a two compartment model, in which about 70% of the ryegrass C decomposed by a first order process of half life 0.25 years and the remainder by a similar process of half‐life 8 years.
THE COMPLEXING OF COPPER BY HUMIFIED ORGANIC MATTER FROM LABORATORY PREPARATIONS, SOIL AND PEAT
Authors: BLOOMFIELD C. , SANDERS J. R. 
Published: July 2006

SummaryThe metal complexing properties of the colloidal and non‐colloidal fractions of water extracts of peat and aerobically composted lucerne, and of chelating resin and alkali extracts of peat and soil organic matter were compared.The contributions of the non‐colloidal fractions to the complexing properties of the whole extracts are considerable, and on a weight‐for‐weight basis are somewhat greater than that of the corresponding colloidal material. No one compound is preponderantly responsible for the complexing action. The complexing activity of the non‐colloidal fractions is confined almost entirely to the acidic constituents. On the basis of the enhancement of the visible range of optical absorbance of the various preparations, Cu2+ is more extensively complexed than Mg2+, Mn2+, Cd2+, Zn2+, Co2+, Ni2+, and Pb2+.