bluuebunny/crossref_metadata_2025 huggingface dataset:
INVESTIGATIONS ON RICE GROWING IN BRITISH GUIANA. II. FIELD EXPERIMENTS TO TEST EFFECTS OF FERTILIZERS, LIME, AND CULTIVATIONS ON YIELD, COMPOSITION, AND NUTRIENT UPTAKE
Authors: GASSER J. K. R.
Published: July 2006

Factorial experiments were done to test the effects of N, P, and K fertilizers and lime on grain and straw yields. In addition, deep ploughing was compared with shallow, static with flowing irrigation, and in two Latin square experiments alternative P fertilizers were tested.

Nitrogen fertilizers increased yields most on the most fertile soil type. Phosphorus fertilizers did not increase yields on the most fertile soil type, gave a moderate increase on the less fertile soils and prevented crop failure on soil containing much exchangeable Al. On the last soil type, water soluble phosphates were more effective than basic slag. Potassium fertilizers improved early growth at one site but did not increase straw and grain yields. Lime did not increase yields, even on the very acid soil containing much exchangeable Al.

The weight of 100 whole grains was determined for rice from experiments sown with‘pure‐line’seed. Increased weight was normally found only when the field treatment increased yield.

The N, P, K, and Ca contents of, and uptake by, straw and grain were determined for three sites with varying responses to applied N and P. Fertilizer N and K had little effect on the composition of straw or grain. Fertilizer P increased the P and decreased the N contents of straw and grain on P‐deficientsoils. Fertilizer P also decreased K content of the straw, increased that of the grain at one site, and also increased the Ca content of straw and grain. Lime increased the Ca content of the straw and of the grain at one site. Uptake of nutrients was affected more by yield than by composition.
DEEPLY WEATHERED ROCK IN SCOTLAND, ITS OCCURRENCE, AGE, AND CONTRIBUTION TO THE SOILS
Authors: FITZPATRICK E. A.
Published: July 2006

In many parts of Scotland, igneous, metamorphic, and consolidated sedimentary rocks are weathered locally to depths as great as 40 feet. The weathered rock is often overlain by glacial till which incorporates some of the weathered material. Elsewhere, the weathered rock extends to the surface and forms the parent material of contemporary soils. Observations of weathering and soil formation in various parts of Europe, Asia, and North America indicate that the occurrence of deeply weathered rock in these countries, as well as in Scotland, may be attributed to weathering in a pre‐glacial period.
BASALTIC SOILS OF SOUTH‐WEST ICELAND. I
Authors: HELGASON BJARNI
Published: July 2006

A preselected grid of sixty‐five randomly arranged sampling sites was the basis for a preliminary soil survey in south‐west Iceland.

The soils were divided into freely drained soils and poorly drained soils, the larger group being freely drained, of which many were shallow lithosols and regosols varying in depth from a few cm. to 1–2 m.

Visible soil characteristics result mainly from physical effects of climate and recent age of the soil parent material. The combined processes of alternate freeze and thaw and wind deposition have disrupted orderly soil morphology. Colour differences, usually varying shades of brown, are therefore minimized, and the mineral matter shows little sign of horizon differentiation, apart from bands of wind‐deposited volcanic ash. The poorly drained soils are mucky in appearance with a non‐indurated layer of bog iron above the permanent water‐table. Waterlogged conditions do not always lead to general gleying.

Under the prevailing sub‐arctic climatic conditions grasses and most other species are shallow‐rooted, forming a surface mat 5–7 cm. thick.

Field texture of freely drained surface soils is usually loamy, but may be extensively conditioned by high organic matter contents. Structure is weak platy, changing to block‐like and/or to single‐grained structure. On drying, soil aggregates usually disintegrate at the least pressure applied.

Many surface features, normally related to frost action, occur, including earth hummocks, scars, V‐shaped gullies, polygons, and stone stripes. Perma‐frost is absent.
USE OF SODIUM EDTA IN THE DETERMINATION OF SOIL ORGANIC PHOSPHORUS
Authors: HARRAP F. E. G.
Published: July 2006

The organic phosphorus contents of a range of soils were determined by the extraction method of Mehta et al. (1954) and by the ignition method of Legg and Black (1955) and the results compared with those obtained by an extraction method using Na2 EDTA and caustic soda. The two extraction methods compared well, especially on soils over pH 5. Lower values were obtained by the ignition method on the more acid soils. The Na2 EDTA method caused less hydrolysis of added glucose‐I‐phosphate than did either of the other methods. In combination with caustic soda Na, EDTA was less effective than Na2 EDTA.
ALUMINIUM AND IRON PHOSPHATE STUDIES RELATING TO SOILS
Authors: BACHE B. W.
Published: July 2006

The reactions of variscite, AlPO4·2H2O, and of strengite, FePO4·2H2O, with dilute aqueous solutions have been investigated. Particular attention has been given to the effects of time of reaction, pH of solution, and the solution/solid ratio. Thermodynamic solubility constants are maintained only at low pH values, viz.:

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Surface hydrolysis reactions occur at higher pH values, releasing phosphate ions into solution and forming more basic insoluble metal phosphates. Solubility equilibria of these minerals are not likely to be relevant in soils at equilibrium.
THE DEVELOPMENT AND MORPHOLOGY OF IRON PAN PODZOLS IN MID AND SOUTH WALES
Authors: CRAMPTON C. B.
Published: July 2006

This investigation concerns a topographic sequence of iron pan podzols developed on loamy and silty parent materials in a zone of high relief and rainfall. The upper ridge flanks are occupied by a soil designated podzol with gleying; a‘Podzol’, except that the eluvial horizon is characterized by a fine prismatic structure. Each prism contains a thin, cup‐shaped iron pan defining the prism core which is anaerobic because of saturation by moisture held within the overlying organic layer for a greater part of the year. Iron oxide concretions occur throughout the remainder of the profile which is kept better aerated through structural cracking within the narrow eluvial horizon. The ridge crests are occupied by the peaty gleyed podzol. Under the thicker organic layer anaerobic conditions exist throughout the eluvial horizon and the iron pan does not occur within the structural units but is confined to the base of this horizon. Iron has probably been mobilized in these soils by microbial action within an anaerobic environment. From the pollen present it appears that the earliest vegetation was high forest dominated by oak, and podzolization probably began under this cover, which was subsequently replaced by a more open forest environment with ferns, initially on the ridge crests, probably resulting from a deterioration of the climate. Gleying probably occurred under an ericaceous flora which succeeded the forest. Grassland has now extended across the ridges, except occasionally on upper ridge flanks.
AN EXAMINATION OF THE BIOLOGICAL REDUCTION METHOD FOR ESTIMATING ACTIVE IRON IN SOILS
Authors: BROMFIELD S. M. , WILLIAMS E. G.
Published: July 2006

Allison 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

The 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.
AN EXCHANGE EQUATION BASED ON POSITIVE ADSORPTION
Authors: HELMY A. K.
Published: July 2006

An exchange equation based on positively adsorbed cations is derived using the double layer model. Some calculations using this equation are compared with calculations using the original Eriksson equation as written by Bolt.
THE EXTRACTABLE MANGANESE OF SOIL
Authors: PAGE E. R.
Published: July 2006

Exchangeable 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

A 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

Surface 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

The 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

The 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

In 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

A 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

In 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

A 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

Humic 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

The 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

An 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

The 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

Schofield'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

Estimates 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

The 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.
ROCK WEATHERING AND SOIL FORMATION ON HIGH‐ALTITUDE PLATEAUX OF MALAWI
Authors: YOUNG A. , STEPHEN I.
Published: July 2006

Humic ferrallitic soils occur at altitudes above 6,000 ft on syenite plateaux. The top‐soil organic‐matter content, 5–10 per cent, exceeds that of all other Malawi latosols. The organic‐matter content of Malawi soils increases rapidly between altitudes of 5,000 and 5,600 ft, corresponding to a fall in mean annual temperature from 65° F to 63° F. The humic top‐soil overlies a yellowish‐red, friable sandy clay or clay with a weak blocky structure. Soils less than 3 ft thick overlie up to 10 ft of weathered rock containing core‐stones. Studies of materials from Zomba Mountain show that, in the formation of weathered rock, the dominant process was bauxitization, with considerable differential removal of silica; gibbsite was derived directly from feldspar. The gravelly bauxitic layer is the parent material for soil formation, in which kaolinization is the dominant weathering process.
THE USE OF MICROPEDOLOGY IN THE STUDY OF SOME ONTARIO PODZOLIC PROFILES
Authors: RENNIE P. J.
Published: July 2006

By adopting a micropedological approach, in which samples were taken at intervals as small as 5 mm, very acute changes in soil pH with depth were revealed. For certain Ontario podzolic profiles under long‐established coniferous forest, pH values changed from around 4 in the topmost humus layer to around 6 at a depth as little as 15 to 20 cm, with little change below this depth. Because much of the magnitude and sharpness of these gradients in properties could be lost by conventional horizon‐sampling, the micropedological approach—used so profitably in some branches of soil science—warrants wider adoption, particularly in shallow profiles.
TOTAL POTASSIUM IN SOILS BY RADIOACTIVITY MEASUREMENTS
Authors: TALIBUDEEN O. , YAMADA Y.
Published: July 2006

The beta‐ and gamma‐analysis methods were fully tested on nineteen British soils; ‘marker’ gamma photo‐peaks of daughter‐elements were used for estimating Th and U, and the 1.46 MeV−40K photo‐peak for K. The photo‐peaks for Th and U that give values for the K contents of the soil closest to the chemically determined values are 208Tl(ThC″)–2.615 MeV and 214Bi(RaC)+–0.609 MeV respecively. Reasonable values for the Th content of these soils are obtained by this method, but U contents seem to be considerably overestimated.
COUNTER DIFFUSION OF Rb86 AND Sr89 IN COMPACTED SOIL
Authors: PHILLIPS R. E. , BROWN D. A.
Published: July 2006

Counter‐diffusion coefficients of Rb86 and Sr89 counter diffusing against H+ ions were measured in Dundee silt loam and Sharkey clay soils at differing soil bulk‐densities. The cation exchange complex of each soil was saturated with either Rb+, Sr++, or H+ and washed free of salts before making diffusion measurements. The water content of the soil on an oven‐dry weight basis was maintained at a constant value for all bulk‐densities; 14.2 and 28.0 per cent for the Dundee and Sharkey soils respectively. These moisture contents correspond to a tension of 2/3 bar for sieved soil. The diffusion coefficients were dependent upon concentration. Average counter‐diffusion coefficients were calculated and related to soil bulk‐density.

Soil compaction of Dundee silt loam had little or no effect upon the counter diffusion of Rb86. The average counter‐diffusion coefficients of Sr89 in Dundee silt loam and Sharkey clay were significantly and linearly related to bulk‐density; as bulk‐density increased the average counter‐diffusion coefficients increased. The average counter‐diffusion coefficients were approximately 0.5–0.75 of the corresponding self‐diffusion coefficients measured previously in these soils. The applicability of counter‐ and self‐diffusion data to practical field problems are discussed.
SATURATION PERCENTAGE AS A MEASURE OF SOIL TEXTURE IN THE LOWER INDUS BASIN
Authors: STIVEN G. A. , KHAN M. A.
Published: July 2006

The saturation percentage is related to the mechanical constituents of a soil:
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and is therefore a quantitative expression of soil texture. Profiles may be described in terms of the S.P.; thus

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Maps may be drawn showing quantitative changes in texture, and associated statements of the reliability of an S.P. estimate and the probable error of the position of a textural contour be made.

Decomposition of the calcium carbonate component should be avoided in routine soil survey work.
THERMODYNAMICS OF CATION EXCHANGE ON CLAY: Ca‐K‐MONTMORILLONITE
Authors: HUTCHEON A. T.
Published: July 2006

Radioactive elution and batch equilibration techniques have been used to obtain isotherms at 30° C, 50°C, and 70° C for the exchange of Ca for K on K‐montmorillonite. From these the changes in enthalpy and entropy were + 3.87 kcal/mole and +6.7 e.u./mole of Ca respectively. The activity coefficient for K decreased from approximately 1.5 to 1 and for Ca from 1 to approximately 0.5 as the fraction of K on the clay increased from 0 to 1. The results are discussed especially in relation to hydration of the ions and adsorption of water on the clay. The entropy of adsorbed water is inferred, from the results, to be less than that for liquid water.
THE HYDROLYTIC EXTRACTION OF CARBOHYDRATES FROM SOIL BY SULPHURIC ACID
Authors: CHESHIRE M. V. , MUNDIE C. M.
Published: July 2006

The parameters of the extraction and hydrolysis of soil carbohydrates by methods involving 24N H2SO4 and N H2SO4 were studied for a sandy granitic loam. Sugars were measured by alkaline ferricyanide, orcinol, anthrone (hexoses), orcinol‐ferric chloride (pentoses), cysteine‐sulphuric acid (methyl pentoses), glucose oxidase (glucose), and also by analysis of the individual sugars by paper chromatography.

After shaking the soil with 24N H2SO4 at 20° C a further period of treatment with N H2SO4 at 100° C was required to obtain maximum hydrolysis of the soil carbohydrates. This period decreased from 17 h to 5 h as the time with 24N H2SO4 increased from 2 to 16 h. NH2SO4 at 100° C alone was less efficient. The extraction of pentoses by 24N H2SO4 reached a maximum within 8 h, and methyl pentoses within 4 h, both declining thereafter. The release of hexoses was continuing after 40 h.

The best compromise involved extraction with 24N H2SO4 for 16 h followed by hydrolysis with N H2SO4 for 5 h. By this treatment yields of pentoses and methyl pentoses were respectively 99 and 92 per cent of the maximum obtainable.
COPPER DEFICIENCY OF WHEAT IN THE RIFT VALLEY, KENYA
Authors: PINKERTON A.
Published: July 2006

The area in the Rift Valley, Kenya, within which soils are deficient in Cu for wheat crops has been delineated. Deficiency is associated with soils, derived from pumice and ash from the Menengai caldera, which contain less than 3 ppm Cu by analysis with Aspergillus niger (M). In pot tests the yields of tomato as indicator crop for Cu deficiency were found to correlate closely with yields of wheat.

Copper sulphate and copper oxychloride when broadcast were both effective in eliminating the deficiency in wheat and resulted in a marked increase in Cu content of the grain. Spraying with either compound, or applying oxychloride as a seed dressing, significantly increased the grain yields but did not result in maximum yield.
SOIL PARTICLE‐SIZE FRACTIONS AND NITROGEN MINERALIZATION
Authors: ROBINSON J. B. D.
Published: July 2006

Fractionation of East African arable soil samples into size groups < 2 mm has significantly influenced mineralizable N values. There was no evidence to suggest that refined soil fractions of < 2 mm would be an advantage for the determination, by incubation methods, of mineralizable N. Differences were more nearly related to simple physical fractionation of the soil. Organic C, total N, and silt contents of the different particle‐size fractions were positively and significantly correlated with mineralizable N; coarse plus fine sand content of the different soil fractions was negatively and significantly correlated with mineralizable N.
THERMODYNAMICS OF K–Ca ION EXCHANGE IN SOILS1
Authors: DEIST J. , TALIBUDEEN O.
Published: July 2006

Cation exchange characteristics of the K:Ca saturated forms of five soils were measured at 25°C and 50°C. The rates of isotopic exchange of 42K and 45Ca were too fast to be measured except that of 42K in the K:Ca Harwell soil at 25°C. The slower isotopic exchange of K in this soil was attributed to the presence of a zeolite, clinoptilolite. The intra‐particle diffusion coefficient, Di, of K in this soil increased with K‐saturation to a maximum at about 40 per cent K, probably because of the ‘blocking’ action of the larger hydrated Ca ions at small K‐saturations in clinoptilolite.

The CEC, measured by isotopic exchange along the K:Ca adsorption isotherm, decreased with increasing temperature probably because some interlayer spaces collapsed.

The standard free energy, enthalpy, and entropy changes were negative for the reaction Ca‐soil+2K+⇌ 2K‐soil+Ca++. These results seem to show that K is more strongly bound than Ca by the soil and that the Ca‐preference shown by the isotherm at small external electrolyte concentration is caused by entropy changes in solution.

Calculated activity coefficients of the exchangeable ions changed with K‐saturation similarly at both temperatures but values at 50°C were smaller than at 25°C.
SOIL FACTORS AFFECTING PLANT UPTAKE OF PHOSPHATE
Authors: GUNARY D. , SUTTON C. D.
Published: July 2006

Short‐ and long‐term uptake of phosphate by ryegrass grown in pots were both well correlated with combinations of the logarithm of the phosphate concentration in solution (log[P]), with a capacity factor (L‐value). It is suggested that log[P] measures an intensity/kinetic complex that takes account of intensity, rate, and diffusion factors. The best correlation with a single parameter was with phosphate adsorbed by anion‐exchange resin, which gives a good measure of the capacity factor and also some measure of the intensity/kinetic complex. On soils of normal phosphate status, the capacity factor tended to be more important, suggesting local exhaustion of labile phosphate. With enriched soils, the intensity/ kinetic complex measured by log [P] was dominant both for short‐ and long‐term uptake.
WATER RETENTION BY OSMOTIC SWELLING OF CERTAIN COLLOIDAL CLAYS WITH VARYING IONIC COMPOSITION
Authors: EL‐SWAIFY S. A. , HENDERSON D. W.
Published: July 2006

Experimental data and theoretical calculations of water retention by osmotic swelling of colloidal homoionic Na‐ and Ca‐montmorillonites, vermiculites, and kaolinites were carried out at several levels of electrolyte concentration, in order to evaluate their respective contributions to the physical response of a soil system to changes in its chemical environment. Similar experiments were conducted for mixed‐ion Na‐Ca‐montmorillonite systems to establish whether a threshold value exists for cation proportions in the exchange positions, at which the physical properties of the system show a sudden change. The results are projected as relationships between the chemical treatment and moisture contents at three equilibrium pressures.

Theoretical calculations, based on the diffuse double‐layer model, predict that montmorillonite systems with a certain form of cation saturation and salt content should have greater swelling pressure or higher capability for water retention than vermiculites, which have greater values than kaolinites under similar chemical conditions. This was confirmed by the experimental data, although measured values were consistently higher than those predicted by theory.

The studies on mixed‐ion montmorillonites show that mutual existence of the two cation species in the clay‐water system produces a nearlinear relationship between exchangeable Na percentage and the moisture retention at a particular equilibrium pressure.
STUDIES ON THE DECOMPOSITION OF PLANT MATERIAL IN SOIL
Authors: JENKINSON D. S.
Published: July 2006

The organic matter in soils containing decomposing 14C‐labelled ryegrass was fractionated chemically. Earlier work on these soils had shown that they contained a small fraction, heavily labelled relative to the rest of the soil organic matter, that was mineralized when the partially sterilized soils were incubated. Reagents effective in extracting heavily labelled‐C included cold o.in HC1, boiling saturated CaSO4 solution, and o.in Ba(OH)2, but neither these nor any other reagent tested could extract material as heavily labelled as that mineralized when partially sterilized soil was incubated. Reagents that extract heavily labelled‐C are poor extractants for humified material and are not strongly hydrolytic: the more vigorous the hydrolysis the smaller the proportion of labelled‐C in the hydrolysate. The amounts of labelled‐C dissolved by Ba(OH)2 from soils sampled after different periods in the field were directly proportional to the amounts of labelled‐C mineralized by those soils when partially sterilized (by exposure to CHC13 vapour), inoculated and incubated.

Balance sheets are presented for the distribution of labelled and unlabelled‐C in fractions separated by hydrolysis with 6N HC1, by NaOH extraction, by neutral pyrophosphate extraction, and by oxidation with H2O2. The fraction remaining after hydrolysis with 6N HC1 was the most lightly labelled and had the widest C/N ratio. The percentage of labelled‐C in the material dissolved by alkali or by pyrophosphate was little more than in the material not dissolved, despite the presence in the soil of fractions differing at least twenty‐fold in intensity of labelling.
THE ASSOCIATION OF MANGANESE AND COBALT IN SOILS—FURTHER OBSERVATIONS
Authors: TAYLOR R. M.
Published: July 2006

Soil Mn was mineralized either as birnessite or lithiophorite in five out of seven widely distributed soils taken from Bermuda, Europe, and the Middle East countries. The majority of the soil Co was associated with these minerals. This agrees with earlier work on Mn in Australian soils and suggests that these two minerals are the most common soil forms of secondary Mn minerals.
ELECTRON‐MICROSCOPE OBSERVATIONS OF IRON OXIDES IN SOME RED SOILS
Authors: GREENLAND D. J. , OADES J. M. , SHERWIN T. W.
Published: July 2006

Electron‐microscope studies of the clay fractions of red soils have shown that free iron oxides are present as small (50–100 A diam) discrete particles frequently clustered to form larger irregular aggregates. Although no evidence of iron‐oxide coatings on clay minerals was found, an association of some of the oxide particles with the edges, but not the faces of kaolinite plates was observed.
A SIMPLE AVAILABLE SOIL NITROGEN INDEX
Authors: ROBINSON J. B. D.
Published: July 2006

Available soil‐N values in commonly cultivated East African soils were determined in the laboratory by several methods, and correlated with one another.

Mineralizable‐N was correlated more with total‐N than with organic‐C. The values of mineralizable‐N (Δ mineral‐N) obtained on aerobic incubation were correlated with crop yield and nitrogen uptake in greenhouse experiments. The yield of dry matter and N uptake by the tomato crop in the absence of applied nitrogen were significantly correlated with Δ mineral‐N in the soils; the degree of correlation decreased with increasing rates of fertilizer‐N applied and Δ mineral‐N and dry‐matter yield were not correlated at the largest rate used. N uptake by the crop was significantly correlated with Δ mineral‐N at all rates of applied nitrogen.

The Δ mineral‐N value determined on soil samples conditioned by 6 weeks incubation followed by 3 weeks air drying was considered to provide a good index to available nitrogen.
VARIABILITY OF SOIL CHEMICAL PROPERTIES IN TWO UNCULTIVATED BROWN EARTHS
Authors: BALL D. F. , WILLIAMS W. M.
Published: July 2006

The variability in pH, loss‐on‐ignition, exchangeable cations, extractable phosphate, and soil moisture, has been studied for the 0.15 cm horizon of uncultivated, unfertilized Brown Earths at two upland grassland sites in North Wales. The results show that there is a high degree of variability in samples taken at the same time on circles of 1 m radius at all sampling locations. For example, coefficients of variation for exchangeable cations (except sodium) average 33 per cent for twenty‐two samples taken on the same occasion at three locations. This spatial variability prevented detection of any additional seasonal trends during a 22‐week summer sampling period. It is essential to consider the importance of spatial variability in any pedological or ecological study.
THE EFFECT OF PROLONGED CROPPING ON THE EXCHANGE SURFACES OF THE CLAYS OF BROADBALK FIELD
Authors: BECKETT P. H. T. , NAFADY M. H. M.
Published: July 2006

Earlier studies have shown that the K‐(Ca+Mg) exchange isotherms of field soils are not greatly changed by cropping, by additions of K‐fertilizer, nor by moderate release of K from fixed forms. The present work shows that very prolonged K‐enrichment or depletion in the Broadbalk trials has led to substantial differences between the exchange isotherms of soils from adjacent plots in proportion to the severity of their K‐depletion.

It is suggested that the changes result from the removal of inter‐lamellar K and the consequent increases in the inter‐lamellar spacings of parts of the clay crystals, which have increased the extent of the surface areas accessible to K‐(Ca+Mg) exchange. It is possible that increases sufficient to cause substantial changes in the exchange isotherms may not be apparent in X‐ray diffraction diagrams. Treatment of the K‐depleted clays with m CaCl2 appears to contract the newly expanded parts of the clay crystals, so that exchange on the occluded surfaces is once again too slow to be observed by the procedures used.