bluuebunny/crossref_metadata_2025_split huggingface dataset:
AN EXAMINATION OF THE BIOLOGICAL REDUCTION METHOD FOR ESTIMATING ACTIVE IRON IN SOILS
Authors: BROMFIELD S. M. , WILLIAMS E. G. 
Published: July 2006

SummaryAllison and Scarseth's biological reduction method was compared with three chemical methods for the removal of iron and aluminium from six Scottish surface soils. When applied to soils which had been pre‐treated with hydrogen peroxide and inoculated with Fe‐reducing bacteria the amount of Fe dissolved by this method was intermediate between Tamm's acid‐ammonium oxalate, the mildest chemical method, and Mackenzie's hydrosulphite method. When applied to untreated soils the amounts of Fe dissolved were sometimes as little as 15 per cent of that removed from peroxide‐treated soils. With the latter soils the amount of soluble Fe increased as the amount of sucrose added to the soil and as the duration or temperature of incubation increased. Al also became more soluble as sucrose increased and the pH of the fermentation decreased. The peroxide treatment rendered A1 more soluble but this could be largely counteracted by increasing the pH before fermentation. The method could be made about five times more specific for Fe than the hydrosulphite method, the most specific of the chemical methods, eight times more than Truog's nascent hydrogen sulphide method, and fourteen times more than the acid‐ammonium oxalate method.The amounts of Fe dissolved by the biological method gave little indication of phosphate sorption capacity and seemed inferior in this respect to acid‐oxalate soluble Fe. A1 dissolved by all methods, especially the chemical ones, was highly related to phosphate sorption.
STUDIES ON SOIL POTASSIUM II. THE ‘IMMEDIATE’ Q/I RELATIONS OF LABILE POTASSIUM IN THE SOIL
Authors: BECKETT P. H. T. 
Published: July 2006

SummaryThe Q/I relations of labile soil K relate its availability or intensity (I) to the amount (Q) present. The activity ratio aK/√(aCa±Mg) has already been proposed as a measure of the intensity factor (part I). The ability of a soil to maintain the activity ratio against depletion by plant roots is governed partly by the character of the pool of labile K and also by the rate of release of fixed K, and by the diffusion and transport of K ions in the soil solution. We may isolate the Potential Buffering Capacity of the pool of labile K by determining the Q/I relation over short periods. Such immediate Q/I relations have been determined for a number of soils. They are all linear over the range of activity ratios commonly encountered in agricultural soils and approximate to familiar ion‐exchange equations. At low values of the activity ratio the Q/I relations are all curved and asymptotic to the Q‐axis.The effects of drying, pH, the addition of lime or K fertilizers, and changes in temperature on the form of the Q/I relations are reported.Oven‐drying a soil, particularly if repeated, appears to cause proportionately more K than Ca to be fixed in the fine clay fraction.
THE EXTRACTABLE MANGANESE OF SOIL
Authors: PAGE E. R. 
Published: July 2006

SummaryExchangeable manganese extracted from soil with calcium nitrate solutions shows some increase as the period of extraction is prolonged. For a given time of extraction the exhangeable manganese of soil behaves as a typical divalent cation obeying simple exchange theory, contrary to a previous report in the literature. Soil particles discriminate between calcium and manganese ions, calcium ions being held more firmly.
STUDIES IN PEDOGENESIS IN NEW SOUTH WALES.
Authors: HALLSWORTH E. G. , WARING H. D. 
Published: July 2006

SummaryA field and laboratory examination has been made of the soils of the Pilliga district of New South Wales, with particular reference to those showing solonetzic morphology. The area consists largely of alluvium from the Jurassic sandstones of the Warrumbungle Range, and grading diagrams for the sandfraction suggest that distribution of the soils follows the changes in depositional pattern.It seems probable that a soil type can occur, morphologically and chemically similar to that which has been described as solodized‐solonetz without ever having been through the stages of solontchak and solonetz. The conditions under which such a profile could develop are:

a semi‐arid to sub‐humid climate, where the mean soil temperature is too high to permit either accumulation of organic matter or the long persistence in the groundwater of organic compounds capable of chelation;
a parent material sufficiently coarse textured to allow movement of clay and of fine silt simply by the mechanical action of percolating water, but not so coarse that the clay is washed completely out of the column;
a parent material extremely low in calcium‐bearing minerals. This condition would obviously be met when the parent material of the present soil was part of a fossil profile formed in a humid or strongly leaching environment;
the presence of vegetation capable of absorbing silica from the soil water and returning it to the surface in leaf fall in a sufficiently finely divided form;
a source of sodium ions.

The solodized‐solonetz could consequently be considered as the normal soil found on coarse‐textured parent material in the semi‐arid to sub‐humid zone of the warm temperate and sub‐tropical areas.
DETERMINATION OF THE TOTAL SPECIFIC SURFACEAREAS OF SOILS BY ADSORPTION OF CETYL PYRIDINIUM BROMIDE
Authors: GREENLAND D. J. , QUIRK J. P. 
Published: July 2006

SummarySurface areas of soil clays can be determined by adsorption of cetyl pyridinium bromide (CPB) from solution. The method is best used with peroxidized, air‐dry samples which have been treated with dithionite‐citrate‐bicarbonate to remove iron and some aluminium oxides, and made homo‐ionic with respect to the exchangeable cation. Apparent CPB areas derived from the plateau of the CPB adsorption isotherm agree with nitrogen areas when no expanding lattice material is present in the sample and when no large proportion of oxides of low surface density of charge remain after the dithionite treatment. When expanding lattice material is present CPB can provide an accurate measure of the internal surfaces provided that the external area is determined independently. Real variations in the crystal size, and hence ratio of external to internal area, are found with montmorillonite, and are exceptionally large for Wyoming bentonite. Specific surface areas determined by the ethylene glycol adsorption method agree reasonably well with areas of non‐expanding lattice clays determined by CPB and nitrogen provided that the specific surface coverage by each adsorbed ethylene glycol molecule is taken as 23Å2. When expanding lattice material is present the agreement is less satisfactory, but is improved in most instances by correcting the area on the basis that molecules adsorbed on external surfaces cover 23Å2 but those on internal surfaces cover 46Å2. Within the range of surface densities of charge found for mica‐type materials the adsorption of CPB is much less sensitive to differences than is ethylene glycol, and therefore enables surface areas to be determined more accurately. CPB is also considerably more convenient to use, since well‐defined adsorption plateaux are formed after overnight shaking.
THE POTASSIUM STATUS OF WEST INDIAN VOLCANIC SOILS
Authors: MOSS P. , COULTER J. K. 
Published: July 2006

SummaryThe potassium status of a group of unfertilized volcanic soils was measured by the intensity, exchangeable, nitric acid‐soluble, fixation, and total potassium values. The soils were classified by the amount of weathering and predominant clay minerals as determined by field characteristics. The soils contained principally pyroxenes, soda‐lime feldspars, and variable quantities of glass and amphiboles. There was a marked absence of potassium‐bearing minerals in the fine‐sand fraction. Clay content varied from 5 to 72 per cent and total potassium averaged 0.38 per cent. Neither potassium highly soluble in nitric acid nor that of limited solubility were related to percentage clay, but both were highly correlated with total potassium. Fixation of potassium was usually low. Potassium intensity, expressed by pK‐1/2 p(Ca 4‐ Mg) values, was determined by equilibrating soil with potassium in calcium chloride solutions. Such values were shown to be similar to those from soil‐solution extracts displaced by alcohol. The potassium‐intensity status was highest in allophane soils and lowest in montmorillonite soils; and was correlated with exchangeable, fixed and highly soluble nitric acid potassium. The last was highly correlated with exchangeable potassium. Partial correlation coefficients showed that the major factors controlling potassium intensity were exchangeable potassium relative to exchangeable calcium and magnesium and the potassium‐fixing ability.
POLYPHENOLS IN PLANT, HUMUS, AND SOIL III. STABILIZATION OF GELATIN BY POLYPHENOL TANNING
Authors: DAVIES R. I. , COULSON C. B. , LEWIS D. A. 
Published: July 2006

SummaryThe role of polyphenols in the stabilization of protein in superficial humus and the relationship of this role to mull and mor formation is discussed.Polyphenols extracted from a variety of plant materials were used to tan gelatin over a wide range of pH. The stability of gelatin, tanned with polyphenols extracted from green beech leaves (mor site), against microbial degradation was then estimated. Over the range of pH found in soils, stability was greatest when the pH of the tanning was low.It seems likely that mor‐forming plant species contain more efficient tannins and the acid condition of the associated soil is better suited to the tanning process. Quantitative differences in tanning substances between mull and mor sites have already been reported by us (Coulson et al., 1960a).
PODZOL SOILS IN THE AMAZON BASIN
Authors: KLINGE HANS 
Published: July 2006

SummaryIn the “terra firme” of the Amazon basin near Manaus, podzol soils occur carrying heath forest. The parent materials are geologically young sandy sediments deposited in valleys. There are no indications that man's activity is one of the pedogenetic factors of the podzol development. Podzols have gradational contact with flanking brown soils developed on loamy Tertiary sediments carrying tropical rain forest. In the ‘terra firme’, that means outside the actual flood plains of the River Amazon and its tributaries, there are sand areas in which soil investigations following the catena principle have been carried out by the author. In the Manaus area the most important pedogenetic factors of the podzol development are lithology and topography. The podzols seem to have developed from parent soils which are characterized by bleaching and eluviation of organic and inorganic substances. The very small Bh layers of podzols which are not correlated with the some metres thick Ae horizons are due to lateral percolation of rain water. On the Tertiary ‘serie of the Barreiras’ brown loams are found carrying high tropical rain forest. On podzols and more differentiated brown soils heath forest is found. Generally, tropical podzols are associated with black‐water rivers. Because the field work was restricted to the Manauús area, the modus of podzol development described in this paper is valuable for that region only. Further studies are necessary to explain the sources of ‘black water’ of other parts of the Amazon basin.
STUDIES ON THE DECOMPOSITION OF PLANT MATERIAL IN SOIL. I.t
Authors: JENKINSON D. S. 
Published: July 2006

SummaryA new method for determining I4C in soil is described.Ryegrass roots and tops uniformly labelled with 14C were allowed to decompose for 4 years in soil under field conditions. About one‐third of the labelled (ryegrass) C was left in the soil after 6 months but thereafter decomposition was much slower, about one fifth of the labelled C remaining after 4 years. Throughout the period, labelled C was less resistant to decomposition than unlabelled C, i.e. the C present in the soil before the labelled ryegrass was added. Even in the fourth year after addition of the ryegrass, the percentage of labelled C in the soil decomposing per year was four times that of unlabelled C.Initially, ryegrass tops decomposed more quickly than roots but after I year the differences disappeared and the same amount of residual C remained from each. For periods of I year and over, the percentage of labelled C retained in a soil with 2.4 per cent organic C was the same as in a soil containing 1 per cent organic C. The percentage C retained was the same when either 0.3 per cent ryegrass tops or 0.6 per cent ryegrass tops were added to the soil. Similar amounts of labelled plant C were retained in soils incubated for 1 year in two contrasting seasons (1959 and 1962).
FIXATION AND AVAILABILITY OF POTASSIUM IN LOESS‐DERIVED AND ALLUVIAL SOILS
Authors: WELTE E. , NIEDERBUDDE E. A. 
Published: July 2006

SummaryIn the various types of loess soils, represented in the form of a catena, migration and alterations of 2: 1 layer‐minerals are the essential cause of a differentiating influence on the phenomena of K‐fixation. The K‐fixation is much greater in river alluvial than in loess soils. The high values of fixation are due to the large contents of clay consisting mainly of expanded 2:1 layer minerals. The river alluvial soils in the delta generally fix much more K than those in the region of the headwaters. By means of pot experiments the alterations of exchangeable‐ and fixed‐K have been examined in their dependence on the varying degree of soil exhaustion by cropping. Although an alluvial soil with K fertilizer showed a large amount of exchangeable‐K, fixed‐K partly diffused into the exchangeable form, and hence precise distinction between exchangeable‐ and fixed‐K was not possible. In contrast, the quantity of exchangeable‐K in the B horizon of a grey‐brown podzolic soil had to be exhausted to the level of the unfertilized soil before fixed‐K was released. In this case the difference in binding strength between exchangeable and fixed‐K could be clearly shown. The release of non‐exchangeable‐K from unfertilized soils was accompanied by a corresponding increase of fixation. Thus, when fertilizer is omitted, charges are set free in the 2:1 layer mineral which will fix any K that is supplied later on.
A STUDY OF POLYSACCHARIDE‐PRODUCING ORGANISMS OCCURRING IN THE ROOT REGION OF CERTAIN PASTURE GRASSES
Authors: WEBLEY D. M. , DUFF R. B. , BACON J. S. D. , FARMER V. C. 
Published: July 2006

SummaryA study has been made of the incidence of polysaccharide‐producing bacteria in the root region of the grass strains Ryegrass (Lolium perenne) strain 823, Cocksfoot (Dactylis glomerata) strain S143, and Timothy (Phleum pratense) strain S50. The root surfaces of the three grasses had the highest percentage of isolates capable of producing capsule and/or slime material (particularly the latter) when compared with the rhizosphere soil and non‐rhizosphere soil. Infra‐red and paper chromatographic analyses of the extracellular material showed that the ability to produce fructosans was commoner in isolates from the root surface.
STUDIES ON HUMIC ACIDS OF SEVEN TYPICAL SOILS OF RAJASTHAN
Authors: SINGH S. , BHANDARI G. S. 
Published: July 2006

SummaryHumic acids from seven different cultivated irrigated soils of the semi‐arid and arid regions were extracted with N/2 NaOH and were analysed for their elementary composition and cation exchange capacity. The methoxyl contents of the cids were determined before and after methylation. There were marked differences in the carbon and nitrogen and in the ash constituents of the acids obtained from different soils. The humic fractions obtained from three darkgrey soil types had higher carbon and lower methoxyl contents than the others. The nitrogen contents of the fractions from three of the soils were comparatively high, being about 8 per cent. These results show that the humic acids of the darkgrey soils are of a more condensed nature than the others. The hydrogen content varied only a little and was less characteristic of the fractions. The high ash contents of all the humic acids is interesting, the figures ranging from 5.8 to 10.6 per cent. Of the ash 31.7 to 39.5 per cent occurs as silica, 19.7 to 24.6 per cent as alumina, 17.5 to 29.0 per cent as iron oxide, 8.3 to 14.5 per cent as phosphorus pentoxide, and 0.54 to 1.88 as the oxides of calcium and magnesium together. The presence of silica is possibly the result, partly at least, of its dissolution during alkali extraction of the soils so that it is held up by humic‐acid particles on acidification of the extracts. The oxides of iron and aluminium, forming about 50 per cent of the ash, appear to be partly present chelated with the humicacid molecules. The methoxyl content varied with the soil type from 0.3 to 1.6 per cent and was increased by methylation of the humic acids by between 5.3 and 7.8 per cent. Methylated humic acids had a much smaller cation exchange capacity than the unmethylated acids.
VEGETATION, ASPECT, AND TIME AS FACTORS OF GLEYING IN PODZOLS OF SOUTH WALES
Authors: CRAMPTON C. B. 
Published: July 2006

SummaryThe study is primarily concerned with the very extensive loamy podzols showing imperfect drainage in the eluvial horizon (Crampton, 1963a). The preferential preservation of Polypodium spores and the less complete floristic sequence recorded by pollen grains in podzols on warm slopes with W. or S. aspect, and greater prominence of Ericaceae and birch in the vegetational history of podzols on cold slopes with N. or E. aspect, suggest that those soils on the colder slopes were both the wetter and more acid in the past. Gleying and the development of associated structures in the eluvial horizon probably began under Ericaceae during early medieval times, and are continuing. In the spoil tips occurring across the north crop of the Coal Measures, where undisturbed for over 100 years, these structures and gleying have developed only in cold, damp pockets associated with Ericaceae on slopes with NW., N., or E. aspect. A similar but less rigid relationship occurs in places of high relief outside the spoil tips. The essential elements of these structures may develop remarkably quickly, and can be seen on opencast sites fifteen years after restoration under pastures which have become impoverished through neglect.
AN INDURATED HORIZON IN SOILS OF SOUTH WALES
Authors: CRAMPTON C. B. 
Published: July 2006

SummaryAn indurated horizon occurs in soils developed in a parent material of drift in Fforest Fawr and the South Wales Coalfield. The variety of soils showing induration, and the depth of induration in some, preclude any specific pedological processes as an explanation of its formation. Fitzpatrick (1956) has suggested that induration and associated structures are relict features of perma‐frosting, induration arising from compression by ice‐crystal growth. Cementation may arise through pedological processes later. Illuviation of clay has occurred in one soil where, also, sesquioxide determinations suggest there has been a little differential downward movement of iron and aluminium in the manner described by Romans (1962) for podzolized soils containing an indurated horizon. The restricted pore space of the indurated horizon has now been mostly infilled with translocated clay. Percolation of water is normally very slow through an indurated horizon, and in this profile has, presumably, been totally deflected by cementation of the indurated horizon. A morphological discontinuity between the podzol profile and indurated horizon has probably been produced by the resulting lateral flow. Where podzolization or illuviation of clay has not occurred, a plane of discontinuity is replaced by a narrow transition zone.
STUDIES OF FUNGI IN A PODZOL
Authors: NICHOLAS D. P. , PARKINSON D. , BURGES N. A. 
Published: July 2006

SummaryThe soil‐sectioning technique was used to allow microscopic examination of fungal populations in relatively undisturbed samples of soil from the horizons of an iron‐humus podzol at Delamere, Cheshire. The technique was also applied to a seasonal study of the quantitative changes in the fungal populations in the A0h layer of the organic horizon and the five mineral horizons of the podzol. For these quantitative assessments, measurement of length of mycelium per unit amount of soil was the most sensitive method, being superior to measurement of density of mycelium or measurement of percentage frequency of occurrence of mycelium.Considerable evidence was obtained during the seasonal study of an increase in mycelium production during the autumn–winter period of the year, clearly demonstrated in the A0h and A1 horizons. This increase in mycelium production appeared to be correlated with the period of maximum leaf fall (and with the corresponding down‐wash of nutrients into the mineral soil).An attempt was made to classify (on morphological grounds) types of mycelium observed, and to relate the morphological groups to the dominant organisms previously isolated from this soil.The data obtained from this study point to the value of microscopic examination of soil in providing essential supplementary data to those obtained from cultural studies.
THE INFLUENCE OF CALCIUM CHLORIDE CONCENTRATION ON THE DETERMINATION OF LIME AND PHOSPHATE POTENTIALS OF SOIL
Authors: LARSEN SIGURD 
Published: July 2006

SummarySchofield's lime and phosphate potentials were determined on four soils using CaC12 solutions varying in strength from 0.002 to 0.05 M. The lime potential, pH–½pCa, was found to be independent of the CaCl2 concentration. The phosphate potential, ½pCa+pH2PO4, of the neutral and alkaline soils decreased when the CaC12 molarity was increased from 0.002 to 0.05. When allowance was made for the formation of a soluble calcium phosphate complex, CaHPO4, the phosphate potential became independent of the calcium chloride concentration in all four soils.
A SPECTROGRAPHIC SURVEY OF REPRESENTATIVE GHANA FOREST SOILS
Authors: BURRIDGE J. C. , AHN PETER M. 
Published: July 2006

SummaryEstimates of the total content of Si, Al, Fe, K, Na, Ca, Mg, Ti, Rb, Li, Ba, Sr, V, Cr, Co, Zr, Ni, Cu, Mo, Ga, and Mn in the fine earth of nineteen Ghana forest soil profiles were found to be related to the underlying geological formations. A general tendency was noted for the content of Al, Fe, Ca, V, Cr, Ga, and Ti to increase with depth and for the Si and Mn content to decrease with depth.
THE TEXTURES OF SOILS IN THE OXFORD REGION
Authors: CLARKE G. R. , BECKETT P. H. T. 
Published: July 2006

SummaryThe results of nearly 500 mechanical analyses on soils of the Oxford region are summarized, to define norms for the textures of soils on the main local parent materials. Surprisingly, the standard deviations of individual clay and silt analyses, about the means for soils on each parent material, bear very little relation to the apparent heterogeneity of the rocks. This probably indicates the prevalence of drift in a formerly periglacial area of mature and sub‐mature relief. The older procedures for mechanical analyses consistently show lower clay, and higher silt and fine sand contents, than the International procedure, by about 15 per cent of the total soil. The coefficients of variation of individual results about the mean for each soil, pooled over all soils and both clay and silt fractions, are 40.6 per cent by the older procedure and 25.3 per cent by the International procedure.