bluuebunny/crossref_metadata_2025 huggingface dataset:
THE PERCOLATION OF RAINWATER THROUGH SOIL DEMONSTRATED BY FLUORESCENT DYES
Authors: REYNOLDS E. R. C.
Published: July 2006

Twelve fluorescent dyes were tested in the laboratory for their stability under conditions of alternate wetting and drying, and persistence of fluorescence in the presence of an acid soil. The strongly fluorescing Pyranine cone, was most suitable for tracing water percolating through soils. In the field this dye could be detected in the soil after several months and couldbe photographed in ultraviolet light. The greater percolation of water against tree trunks and lateral movement in the humus layer were demonstrated.
INFLUENCE OF ADSORBED SODIUM AND GYPSUM CONTENT ON PERMEABILITY OF GLACIAL TILL SOILS
Authors: VAN SCHAIK J. C.
Published: July 2006

The permeability of glacial till soils having mainly montmorillonite in the clay fraction was negligible when the exchangeable sodium percentage (ESP) exceeded 15 to 20. Relatively higher permeability values were obtained in soils containing gypsum, but water transmission through such soils was negligible above ESP of 30 to 35. The relative decrease in permeability with increase in exchangeable sodium depends not only on the ESP and electrolyte concentration in the soil solution but is affected by the types of clay minerals.
THE INTERACTION OF PARAQUAT (1: 1′‐DIMETHYL 4:4′‐DIPYRIDYLIUM DICHLORIDE) WITH MINERAL SOILS
Authors: KNIGHT B. A. G. , TOMLINSON T. E.
Published: July 2006

Investigation of the adsorption of 1:1′‐dimethyl 4:4′‐dipyridylium (paraquat) dichloride by a range of soils, using a solution‐equilibration technique, has shown that the adsorption is characterized by three factors:

1. Up to a limiting value, defined as the Strong Adsorption Capacity (SAC), the solution concentration of paraquat is reduced below the level of chemical detection by suspended soil: this strongly adsorbed paraquat is preferentially held against 0.1 to 2.0N solutions of ammonium ion. A range of strengths of adsorption probably exists within the strong adsorption range, but the greater part of the strongly adsorbed material is de‐activated herbicidally; this accounts for the herbicidal de‐activation of paraquat in soils.

2. Removal of soil organic matter by treatment with hydrogen peroxide usually does not greatly change the SAC. Strong adsorption of paraquat is primarily a property of clay minerals, and the presence of expanding lattice minerals is of particular importance.

3. For fortifications above the strong adsorption region, there is a region of weaker adsorption but the total adsorption capacities of soils at saturation are less than their cation exchange capacities for inorganic cations. Taken with the difficulty of displacement, this indicates that the adsorption of paraquat is strongly influenced by factors other than simple electrostatic interaction.
POTASSIUM‐CALCIUM EXCHANGE EQUILIBRIA IN SOILS: THE LOCATION OF NON‐SPECIFIC (GAPON) AND SPECIFIC EXCHANGE SITES
Authors: BECKETT P. H. T. , NAFADY M. H. M.
Published: July 2006

Several studies (e.g. Bolt et al., 1963; Beckett, 1964a) of the exchange equilibria between K and Ca on soil colloids or pure clay minerals have drawn attention to the presence of sites with different affinities for K. There is so far no evidence to indicate the location of sites with the highest affinity, though several workers (e.g. van Schouwenburg and Schuffelen, 1963) have assumed that they lie on the edge‐faces of stacks of clay plates, or in the spaces between the expanded leaves of partially weathered stacks of clay plates.

Earlier work has resolved the K: Ca exchange isotherms of soils and clays into a curved part at low values of aK/√aCa, attributed to exchange at sites with a high specific affinity for K, and an upper linear part commonly described by the Gapon equation and attributed to non‐specific sites.

The present work on soil clays and clay minerals shows that Na hexametaphosphate or changes in pH affect the curved but not the linear part; cetyl trimethyl ammonium bromide and changes in the amount or charge of exchangeable Al affect the linear but not the curved part of the isotherms. At low pH, the linear but not the curved part of the kaolinite isotherm obeys Schofield's Ratio Law. Grinding has more effect on the curved than on the linear part. So the specific sites are attributed to the edges or peripheral interstices of stacks of clay plates, and the non‐specific sites to their planar surfaces.

The specific sites take up K more slowly from solution than the non‐specific sites. The isotherms of completely dispersed bentonites have no curved part. The specific sites are attributed to the wedge‐shaped interstices opened between clay plates by weathering, from which exchange is diffusion‐controlled.

Added organic cations reduce the numbers of both kinds of site; peroxide treatment increases them.

This paper confirms that the exchange sites with highest affinity for K are indeed associated with the edges, rather than the faces, of stacks of clay plates.
THE HUMIC ACIDS EXTRACTED BY VARIOUS REAGENTS FROM A SOIL
Authors: THENG B. K. G. , WAKE J. R. H. , POSNER A. M.
Published: July 2006

The infra‐red, visible, and ultra‐violet absorption spectra of humic acids extracted from a red‐brown earth by various reagents, are described. The variations in the intensity of various absorption bands in the infra‐red spectra are related to the method of extraction, yield, and titration data. For example, the humic acids extracted by milder reagents give rise to spectra which show relatively weak aliphatic C‐H absorption whilst the intensity of the bands arising from oxygen‐containing groups (carboxyl and ketone carbonyl) is relatively strong. The opposite behaviour is shown by the corresponding bands in the spectra of humic acids extracted by stronger reagents. The intensities of other infra‐red bands are also considered.

The optical density of the C═O band at 1720 cm−1 in the humic‐acid spectra and of the carboxylate ion band at 1380 cm−1 in the spectra of the K salt is linearly related to the exchange capacity. The presence of carboxyl groups ionizing above pH 7 and extending to as high as pH 11, is demonstrated.
WATER MOVEMENT IN DRY SOILS
Authors: ROSE D. A.
Published: July 2006

Semi‐infinite columns of dry soil closed at one end had the other exposed to a turbulent atmosphere at constant relative humidity (0.98) and a range of constant temperatures. After varied times the water content of the columns was measured gravimetrically, in 1 cm layers, from which the total quantity taken up Q and the distribution of water content Ø with time t and distance x were found. Assuming that the Boltzmann transform, λ=xt−t can be applied to the standard diffusion equation, two soil parameters are derived. A test of the assumption is that Ø should be uniquely dependent on λ, and then the diffusivity is calculable from

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where Øt is the initial uniform water content. The second parameter—the sorptivity, S= Qt−½—and is not independent of Øt or the value maintained at x= 0.

Results show that in a clay soil, between pF 5.8 and pF 4.2, water moves predominantly as vapour: in a non‐swelling silicate mineral (sepiolite) there is significant liquid movement between pF 5.1 and pF 4.2. Long‐continued use of organic manure has little effect on either D or S; aggregate size has some effect, in opposite senses for a sand and a clay; a mulch or a still atmosphere affects S but not D; evaporation suppressants decrease S; ignition decreases S and greatly alters D; and degradation of structure causes small changes in D.
ANDESITE WEATHERING
Authors: HENDRICKS D. M. , WHITTIG L. D.
Published: July 2006

Using the isovolumetric method of analysis, it is observed that all major chemical constituents except ferric iron and lattice water suffer loss during weathering of hypersthene‐ and olivine‐andesite to saprolite (weathered rock) in an acid leaching environment. Si, Ca, K, and Na are removed rapidly during the early stages of weathering of both rocks. Mg loss is delayed somewhat because it is found in both rocks in relatively large hypersthene phenocrysts which tend to resist weathering. Total Fe, Al, and Ti show moderate losses during weathering. During weathering of the two rocks, the loss of Si, Al, and total Fe is relatively greater from the hypersthene andesite. This is believed due to greater leaching intensity and greater acidity of leaching solution at the hypersthene andesite location. In addition, more pronounced alternate wetting and drying, which occurs at the olivine‐andesite location, exert a strong influence in stabilizing Fe and Al.
THE GENESIS OF SOME BASALTIC SOILS IN NEW SOUTH WALES
Authors: CORBETT JANICE R.
Published: July 2006

Field and laboratory investigations of 182 soil samples and their underlying basalts in the Inverell area indicated that not all of the red soils in the area are relicts of Tertiary laterization as was previously thought. The soils on basalt were divided morphologically and mineralogically into shallow (black, brown/ chocolate, and red) and deep (krasnozems and lateritic soils) profiles. The mineralogy of the sand fractions of the shallow soils, which were similar in all respects except colour and location, suggests that they are young soils as the heavy minerals in the sand fractions are dominantly pyroxene, olivine, and the black opaque minerals which weather quite rapidly. The shallow black and brown/chocolate soils occupy whole slopes under grassland vegetation or grassland with trees, while the shallow red soils are restricted to steeper well‐drained slopes and crests where trees tended to dominate grass. In similar areas throughout the New England region red soils are found on basalt in areas receiving 75 cm or less average annual rainfall, although previous workers have assumed that red soils develop from basalt at present only in areas receiving more than 140 cm average annual rainfall. The deeper soils, which were characterized by a lower pH, occupied upper or upper and middle slopes. The dominance of the resistant altered opaque minerals in these soils suggests that they are relict soils. The krasnozems showed little horizon differentiation apart from a slight darkening of the upper 8–10 cm. The lateritic soils had marked horizons, with laterite overlying mottled and pallid zones, the whole sequence being deeper than the krasnozems. The lateritic soils contained a high percentage of heavy minerals in the sand fractions in contrast to all the shallow profiles. Only one period of laterization is indicated in the area, although the laterite levels were not always accordant.
DISTRIBUTION OF PYROPHOSPHATE‐EXTRACTABLE IRON AND ORGANIC CARBON IN SOILS OF VARIOUS GROUPS
Authors: BASCOMB C. L.
Published: July 2006

Potassium pyrophosphate (0.1m) removes very little Fe from crystalline Fe oxides at pH 10, but peptizes finely divided hydrous amorphous oxides and organic matter in soils.

Fe and C contents of extracts from each horizon of twenty‐six British soil profiles show distinctive patterns, independent of the residual dithionite‐soluble Fe. Thus extracts of humus Fe podzols have maximum Fe and C in the B horizon, peaty gley podzol has maximum Fe in the B horizon but maximum C in the surface. These groups are differentiated from non‐podzols which have maximum pyrophosphate extractable Fe and C in the surface horizon, decreasing with depth. Intermediate patterns help to quantify differences in soils of classes having properties of more than one soil group.
RELATIONSHIPS BETWEEN SOIL VOLUME USED BY ROOTS AND NUTRIENT ACCESSIBILITY
Authors: CORNFORTH I. S.
Published: July 2006

Increasing the volume of soil available to plants growing in pots increased yields of oats, ryegrass, kale, and tomatoes and decreased the intensity of rooting; it increased the supply of N more than that of P, as P uptake was correlated with root intensity and N uptake was not. Responses to P fertilizer were greater in the larger volumes of soil, but responses to applied N were less than in small volumes. Isoquants showed that, when soil volume is restricted, it is more important to apply a mobile nutrient (nitrate) than an immobile nutrient (phosphate), although the value of either nutrient in compensating for inadequate soil volume depends on the supply of the other.
THE EQUILIBRIA OF K:Al EXCHANGE IN CLAY MINERALS AND ACID SOILS1
Authors: COULTER B. S.
Published: July 2006

Conventional K: Al exchange isotherms for montmorillonite showed that Al3+ was strongly preferred to K+ in o‐oin solutions. The exchange coefficient, K', calculated using the isotopically exchangeable K, was greater than unity and did not vary with the Al‐saturation or with the initial pH of the AlCl3 solutions.

Isotherms for vermiculite, illite, and soils in o·oin solutions also showed Al3+‐preference but unlike those for montmorillonite were not asymptotic to qAl/qo= 1, qAl being the amount of adsorbed Al and qo the total adsorbed (Al + K), indicating that some of the isotopically exchangeable K could not easily be exchanged by Al3+ ions; this difficultly exchangeable K (DEK) was estimated for each exchanger. K' values for vermiculite, illite, and soils were less than unity and did not vary with Al‐saturation or initial pH if the isotopically exchangeable K was corrected for DEK. This showed that K+ was adsorbed more strongly than Al3+. Strengths of K+ adsorption referred to Al3+ as the counter‐cation were in order: soils > vermiculite, illite > montmorillonite.
SOME PHYSICAL AND CHEMICAL PROPERTIES OF SOILS IN THE BEQA'A PLAIN, LEBANON
Authors: SAYEGH A. H. , SALIB A. J.
Published: July 2006

Physical and chemical properties of red soils, white rendzina, light chestnut, dark chestnut, grey, black, and recent alluvial soils as mapped by Geze (1956) were compared statistically.

No statistically significant differences were found between surface soil (0–15 cm) and upper subsoil (15–30 cm) in any properties.

Red soils were significantly lower than the others in total N, CEC, and CaCO3 content. Recent alluvial soils were high in montmorillonite probably derived from the white rendzinas. The rendzinas were significantly higher in available P and CaCO3 than any other soil.

Black and grey soils, previously classified as one category, should be separated as they were significantly different in most properties.
A COMPARATIVE STUDY OF NITRIFICATION IN SOILS FROM ARID AND SEMI‐ARID AREAS OF ISRAEL
Authors: ETINGER‐TULCZYNSKA R.
Published: July 2006

The influence of different factors on the nitrification of an added ammonium salt and inherent soil‐N in soils from arid and semi‐arid areas of Israel was investigated.

Nitrification of ammonium‐N proceeded rapidly at 28°C but was inhibited partially or completely in soils incubated at 37·40°C. In contrast, nitrate formation from inherent soil‐N proceeded better at 37·40 °C than at 28 °C.

Bacteriological examination showed that a temperature of 37·40 °C had an injurious effect on the population of nitrifiers, especially the nitrate‐forming bacteria. Nitrification by the Nitrosomonas‐Nitrobacter group in culture media was also markedly inhibited at 37 °C as compared with that at 28 °C.

Chloromycetin at a concentration of 25 mg per 100 g soil, and potassium chlorate at a concentration of 10‐3m suppressed the formation of nitrate from ammonium, but did not exert any appreciable effect upon nitrate formation from inherent soil nitrogen. Sodium sulphacetamide inhibited the production of nitrate from ammonium‐N more strongly than that from inherent soil‐N.

Marked differences in the two nitrification processes in the soils investigated provided good evidence that the greater part of nitrate originating from soil‐N is produced by some process other than that which is responsible for nitrification of ammonium‐N.
A STEADY‐STATE METHOD FOR DETERMINING DIFFUSION COEFFICIENTS IN SOIL
Authors: TINKER P. B.
Published: July 2006

A simple method for determining steady‐state diffusion coefficients of cations in soil is described, with cation exchange papers as sources and sinks, which may be used at a range of moisture contents. It was tested on the inter‐diffusion of Ca and Mg in a Coral Rag clay soil. Sectioning and analysis of the soil after the steady state was reached gave a plot of composition with distance along the cell which was similar to the curved Ca‐Mg exchange isotherm, and indicated that nearly all the flux was through the liquid phase. Values of the tortuosity factor f1 could therefore be found. There were indications that HCO3 ions were formed, and increased the flux in some experiments. Transient‐state diffusion coefficients were measured in the same experiments, and agreed fairly well with the steady‐state results.
AN OSMOTIC METHOD FOR STUDYING THE SUCTION/MOISTURE CONTENT RELATIONSHIPS OF POROUS MATERIALS
Authors: PRITCHARD D. T.
Published: July 2006

Zur's osmotic method was simplified by placing 2 g particulate samples of finite size (e.g. 1–2 mm) in 6·5 mm diam sacs made of semi‐permeable membrane tubing and suspending these in solutions of polyethylene glycol (PEG), molecular weight approx. 20,000. Moisture content was measured daily by weighing the sacs.

PEG solutions of low pF were calibrated by hanging sacs containing water in them, and observing the difference in height of the liquid surfaces at equilibrium. The range was thus extended from pF 3·0‐4·2 to pF 1·5‐4·1.

Wetting over the whole range takes 8 days and drying, from saturation, 16 days. Six polythene boxes (each holding 3·25 1 of PEG) used simultaneously, give the equivalent of wetting curves for 24 samples per day.

In the isopiestic method, used for comparison over the range pF 3·5‐4·0, nickel crucibles containing 1 g samples were partly immersed in control solutions of sodium chloride, in vacuum desiccators, in a temperature controlled double water‐bath.

Structural stability is a problem with certain soils, and more durable membranes are desirable.
THE MEASUREMENT AND MECHANISM OF ION DIFFUSION IN SOILS V. DIFFUSION OF HYDROGEN ION IN SOILS
Authors: FARR E. , VAIDYANATHAN L. V. , NYE P. H.
Published: July 2006

The linear diffusion of H ion from a series of soil blocks, containing essentially H and Ca only as exchangeable cations, into a sink solution maintained at pH 5·2, has been studied.

In three separate series of experiments, first the total concentration of diffusible H, then the amount of diffusible H in the pore solution, and finally the amount of exchangeable H associated with the solid phase have been successively varied. Account has also been taken of the variation in activity ratio: aH/√a ca. The effect on the resulting flux and diffusion coefficients of the ion has been related to the H buffer power of the soil.

The impedance factor of the ion through the liquid pathway is slightly lower than that for other cations determined in soil. The diffusive flux of H occurs through the liquid pathway, and the contribution of solid‐associated H is small, except possibly at low H ion solution concentrations.
MICROPEDOLOGICAL STUDY OF A CHERNOZEMIC TO GREY WOODED SEQUENCE OF SOILS IN MANITOBA
Authors: PETTAPIECE W. W. , ZWARICH M. A.
Published: July 2006

Micromorphological studies were conducted on Orthic Black (chernozem), Orthic Dark Grey (degraded chernozem), and Orthic Grey Wooded (podzolic) soil profiles, developed on medium‐textured, moderately calcareous glacial till. The surface horizons ranged in characteristics from the plasma‐rich Ah horizon of the Orthic Black, which had chernozemic fabric, to the plasma‐deficient Ae of the Orthic Grey Wooded, which showed isoband fabric. The B horizons exhibited an increase in ped density, going from the Orthic Black to the Orthic Grey Wooded, with concomitant increase in cutan formation.

The interpretation of micromorphological features led to the conclusion that many field‐observed characteristics are manifestations of the microfabric of the various horizons. It is suggested that physical disturbances such as freezing and thawing, wetting and drying, and root pressures play an active role in pedogenesis.
MICROMORPHOLOGY OF SOME TROPICAL ALLUVIAL CLAY SOILS
Authors: SLAGER S. , JONGMANS A. G. , PONS L. J.
Published: July 2006

The micromorphological properties of some marine and estuarine tropical clays from Holocene coastal plain soils of Surinam and Thailand have been explained against the background of sedimentation and initial soil formation.

During geogenesis stratified sediments are formed, above which are sediments with slightly disturbed stratification, with or without matric faecal pellets.

Pedogenesis during the sedimentation phase included development of channels in the sediment, formation of channel neostrians, biological homogenization, possibly pyrite accumulation, and partial oxidation and precipitation of iron as ferric hydroxide.

During the brackish water phase pyrite accumulates in various amounts, mass illuviation may occur, part of the iron may oxidize and precipitate and part of the pyrite may be oxidized.

During and after the swamp phase further oxidation and precipitation of iron as ferric hydroxide occurs, ferric hydroxide crystallizes into goethite. Pyrite becomes oxidized, resulting in the formation of jarosite, gypsum, silica, and ferric hydroxide.
THE STABILITY OF DICALCIUM PHOSPHATE DIHYDRATE IN SOIL
Authors: PROBERT M. E. , LARSEN S.
Published: July 2006

The rate of dissolution of dicalcium phosphate dihydrate (DCP) when incorporated in moist soil was investigated using 32P. The moisture content of the DCP‐soil mixture, the surface area of the DCP particles and the temperature of incubation of the system are all directly related to the rate of dissolution of the DCP. These results may be explained using a diffusion model in which phosphate ions diffuse from a water film adjacent to the DCP towards a sink provided by the soil.
EVIDENCE OF DICALCIUM PHOSPHATE PRECIPITATION IN A CALCAREOUS SOIL
Authors: LARSEN S. , WIDDOWSON A. E.
Published: July 2006

The‘precipitated‐calcium/precipitated‐phosphorus’ mole ratio approached a limiting value of 1 as the amount of phosphate, added to a suspension of calcareous soil in 0·01m CaC12, was increased, indicating the precipitation of dicalcium phosphate. The phosphate and lime potentials provided further evidence that dicalcium phosphate was present at high rates of phosphate addition.
ENZYME ACTIVITIES AND OXYGEN UPTAKES OF SOILS UNDER PASTURE IN TEMPERATURE AND RAINFALL SEQUENCES
Authors: ROSS D. J. , ROBERTS H. S.
Published: July 2006

Some glycoside hydrolase activities, dehydrogenase activities, and oxygen uptakes were studied in New Zealand topsoils under pasture, arranged in two zonal soil sequences: one in which mean annual temperature varied (5 soils), and another in which mean annual rainfall varied (7 soils). Differences in other site factors were small.

All the biochemical activities were negatively, but not usually significantly, correlated with mean annual temperature. Activities did not appear to be influenced by differences in the proportions of grasses and legumes (mainly clovers) or in the clay contents at the different sites.

Activities of glycoside hydrolases (a) without added substrate and (b) with added starch were significantly correlated with mean annual rainfall, and with soil moisture and organic C contents; activities of (c) enzymes hydrolysing sucrose were significantly correlated only with soil organic C contents. The ratios of (c) to (b) declined significantly with increasing mean annual rainfall.

Dehydrogenase activities were highest in winter samples and significantly correlated with both soil moisture content and pH.

Oxygen uptakes were significantly correlated with numbers of viable bacteria in soils of the rainfall sequence although they were not significantly correlated with annual rainfall nor with soil organic C contents. Oxygen uptakes and dehydrogenase activities were not significantly interrelated.

Results were compared with previous studies of grassland soils.
CRUSTING OF RIVER ESTATE SOIL, TRINIDAD, AND ITS EFFECT ON GASEOUS DIFFUSION, PERCOLATION, AND SEEDLING EMERGENCE
Authors: AHMAD N. , ROBLIN A. J.
Published: July 2006

The River Estate Loam in Trinidad is micaceous. It is weakly structured and prone to surface crusting which results in decreased gaseous diffusion, infiltration‐ percolation, and seedling emergence. Mulching with ‘Encap’ (a liquid petroleum product) increased infiltration but not seedling emergence whereas ‘Krilium’ (sodium polyacrilonitrile) was more effective in improving seedling emergence. Bagasse mulch had a beneficial effect on infiltration but in common with pen manure was not very effective in aiding seedling emergence. Thin section examination showed that the uncrusted soil had an open structure with a large volume of pores, but, on crusting, the particles became densely packed with negligible air‐spaces. Soil particles on die surface of the crust showed some degree of orientation but below the surface there was no such tendency, although particles coalesced with negligible air‐spaces. The liquid petroleum mulch prevented crust formation and maintained a stable soil structure.
QUALITY CONTROL IN SOIL SURVEY INTRODUCTION: I. THE CHOICE OF MAPPING UNIT
Authors: BIE S. W. , BECKETT P. H. T.
Published: July 2006

The quality of a soil map depends on its utility for practical purposes and should be judged by this standard. The Introduction to this series suggests how utility may be measured, and briefly lists decisions in the planning and execution of a soil survey which determine the utility of the resulting soil map. Subsequent papers in the series discuss their influence separately.

Part I discusses the policy decision on the kind of mapping unit. It reviews different kinds of mapping units and presents a scoring procedure to compare the ceilings which each imposes on the utility of a soil map. The scoring procedure assumes that the whole extent of every mapped soil unit exactly matches its description in the map legend. On this basis it estimates the average probability that the soil profile class at any randomly located site within a survey area is correctly predicted. The score is a ceiling, attainable only if the execution of the survey were perfect, and no mapping unit contained profile classes not predicted from its legend. Even so the legends of many published soil maps achieve scores of 50 per cent or less. The paper stresses the importance of adequate aids to predict the occurrence of individual profile classes within compound mapping units containing more than one. These points are illustrated from Australian experience.
GENESIS AND MORPHOLOGY OF SOME ALPINE PSEUDOGLEY PROFILES
Authors: BOUMA J. , VAN DER PLAS L.
Published: July 2006

Two representative Alpine pseudogley profiles from a high Alpine region in Switzerland are described. Their genesis is mainly a function of illuviation, oxidation and reduction processes, and frost action. A relationship between soil type and vegetation was not found. The higher content of silt in the topsoil can be attributed largely to sedimentation of wind‐blown particles.
THE ADSORPTION OF ALUMINIUM FROM HYDROXY‐ALUMINIUM SOLUTIONS ON TO FITHIAN ILLITE
Authors: COLOMBERA P. M. , POSNER A. M. , QUIRK J. P.
Published: July 2006

The adsorption of aluminium from hydroxy‐aluminium perchlorate solutions on to Fithian illite in the presence of 0.06M and 0.5M NaClO4 is described by Langmuir‐type adsorption isotherms at constant OH/A1 ratio. The binding constant for aluminium, and the amount of aluminium that can be adsorbed, increases with increasing OH/A1 ratio of the solution from which it is adsorbed. The Langmuir‐type adsorption isotherms can be explained on the basis that hydroxy‐aluminium species present in solution are adsorbed in constant relative proportions and that the relative proportions of hydroxy‐aluminium species remain unchanged on dilution of the hydroxy‐aluminium solutions at constant ionic strength. If the ionic strength at which the isotherm is determined is decreased from 0.5M to 0.06M NaClO4, the binding constant for adsorption of aluminium is not significantly altered. This can be understood if the adsorption process is not one of exchange but rather the formation of H bonds between the hydrolysed polymer species and the surface.

Negative adsorption measurement at low and increasing ionic strength indicates the changes in charge on the adsorbed hydroxy‐aluminium polymers as their concentration in solution is increased.
SOIL FLUORINE
Authors: LARSEN S. , WIDDOWSON A. E.
Published: July 2006

The development of techniques for measuring soluble and labile soil fluoride using a specific‐ion fluoride electrode are described. The methods evolved were used to assess the fluoride status of numerous agricultural soil samples in addition soils which had received known fluoride additions. Two soil profiles were analysed with respect to distribution with depth of soluble and labile fluoride.

The equilibrium‐fluoride concentration was determined after shaking the soil with a 0.01 M CaCl, solution. Isotopically exchangeable (labile) soil fluoride was determined by use of the radioactive fluorine isotope 18F. These labile fluoride values were well correlated with the amount of soil fluoride extracted by an anionexchange resin, and the latter method was consequently adopted for further determinations of labile soil fluoride.

Nearly half the 1OO agricultural soil samples examined gave fluoride concentrations < 0.2 ppm in 0.01 M CaCl, extracts whereas labile fluoride values were evenly distributed around a mean of 20 ppm. For any given pH value, there appeared be an upper limit to the solubility of soil fluoride. Application to soil of superphosphate (in the field) or of fertilizer containing fluoride (in the laboratory) brought about increases in soluble soil fluoride.
SOURCES OF ERROR IN THE DETERMINATION OF SOIL POTASSIUM ACTIVITY RATIOS BY THE Q/I PROCEDURE
Authors: MOSS P. , BECKETT P. H. T.
Published: July 2006

Equilibrium activity ratios such as aK/(aca+Mg)½ may be determined by analysing a solution in equilibrium with a soil. The Q/I procedure is one method for establishing the composition of such a solution. Several approximations have been proposed to simplify this procedure or the necessary calculations. This paper reviews the main sources of error in the Q/I procedure.

Errors may arise in the sampling, preparation, and storage of soil samples: it is best to analyse samples as soon as possible after sampling, with no preparation other than gentle sieving.

The Q/I procedure rests on certain implicit assumptions which will not strictly apply if there is any substantial exchange, between exchangeable cations and soluble salts or microbially dissolved carbonates, during determinations. This paper demonstrates that such exchange does indeed occur during the determination of the equilibrium activity ratios of soils at 5 < pH > 6, but that the errors may be ignored in British soils at pH > 5. Modified interpolation procedures designed to minimize errors from these causes appear to introduce larger errors than they avoid.

The paper also indicates the conditions under which various approximations in the calculations may be employed.
THE CLASSIFICATION OF ARID ZONE SOILS
Authors: WESTERN S.
Published: July 2006

Soils in regions of arid and semi‐arid climates exhibit only limited pedogenetic profile development, and they might be more usefully described, classified and mapped in terms of their depositional character. The main source of understanding of their origins and practical significance is likely to be the sedimentary geomorphology of the area concerned, rather than the minimal pedogenetic features. The term ‘sedosols’ is proposed for these soils and a method of classification is outlined, based on depositional features and origins.

Sub‐orders are based on mode of deposition to give four sedimentary families, viz. fluvial, littoral, aeolian, and anthropic.

In lower category classification, series based on pedogenetic features cannot be defined and are replaced by the ‘depositional series’ characterized by the types of sediment (e.g. coarse textured, fine textured; saline, non‐saline).

Typical phases are based on soil depth and degree of erosion. Salinity induced by irrigation is also best recognized at phase level as it is essentially an ephemeral feature.

The three major differentiating characteristics of sedosols are soil texture, degree of depositional stratification and effective soil depth.
NUCLEATION, POLYMERIZATION, AND PRECIPITATION OF FeOOH1
Authors: HSU PA HO
Published: July 2006

Fresh Fe(ClO4)3 solutions, 0.01 M or 0.001 M in iron (III), were seeded with iron (III) hydroxide brown sols and the reaction processes were investigated. In two experiments, HC1O4 was added to fresh Fe(ClO4)3 solutions to lower their degrees of super saturation with respect to iron (III) hydroxide. Depending upon the quantity of seeding solution added, it was found that samples differed greatly in appearance and in the stability during ageing. With a small amount of seeding solution added and following a relatively long induction period, the sample rapidly developed to a dense, cloudy yellow suspension with FeOOH precipitate settled shortly afterwards. With an increased amount of seeding solution added, the sample gradually became more brownish and less turbid and eventually a clear brown sol was observed. Although α‐FeOOH was the major hydrolysed species in all samples, a yellow precipitate which settled under gravity was found only in those containing a small quantity of seeding solution. The above results provide experimental evidence supporting the hypothesis (Hsu and Ragone, 1972) that the initial number of nuclei relative to the concentration of mono‐meric species is the key factor governing the appearance and the stability of an hydrolysed iron (III) solution.

In another experiment, varying amounts of a seeding solution were added to a fresh, pure 0.001 M Fe(ClO4)3 solution to which no HC1O4 was added. All samples rapidly hydrolysed to clear brown sols in less than 6 hours and no noticeable seeding effect was observed. It is suggested that a pure 0.001 M Fe(ClO4)3 solution is highly supersaturated with respect to iron (III) hydroxide and a large number of nuclei spontaneously form in situ shortly after preparation.
A COMPARISON OF DATA FROM AGRICULTURAL SOIL SURVEYS WITH ENGINEERING INVESTIGATIONS FOR ROADWORKS IN AYRSHIRE
Authors: McGOWN A. , ILEY P.
Published: July 2006

Recently a number of outline soil survey maps, on a scale I: 25 000, each covering some IOO km square, have been made available by the Soil Survey of Scotland to County Advisory Officers) Planning Officers, and others who have specialist requirements. In North Central Ayrshire a number of major roadworks have been completed in recent years and the Kilmarnock and Hurlford Bypasses are at present under construction. Site investigations have been undertaken in connection with these works and construction records kept. These make possible the assessment of the usefulness of the soil survey maps for initial route and realignment planning of roads.

The delineation of the various soil associations on the soil survey maps related very closely to the limits of the various engineering soils encountered. The groupings adopted by the soil surveyors for boulder clays have, however, been found to be narrower than presently required by engineers) while the groupings adopted with respect to the raised beach and alluvial deposits too wide.

It is suggested that the engineering behaviour of boulder clays needs closer examination and any correlations between engineering and soil association groupings should be sought. Also if the grading, water content, and bulk density of the raised beach sands and gravels could be given by the soil survey, this information would permit engineers to make a much better judgement of the road‐bearing capacity of these materials. Alluvial deposits should be similarly tested and distinguished as either riverine or lacustrine deposits.

To avoid duplication of effort in the future when geotechnical maps are produced and to gain the maximum benefit of the information so far collected, a closer liaison between engineers and the Soil Survey of Scotland is suggested.
DISTRIBUTION OF INOSITOL PHOSPHATES, PHOSPHOLIPIDS, AND NUCLEIC ACIDS AND MINERALIZATION OF INOSITOL PHOSPHATES IN SOME BANGLADESH SOILS
Authors: ISLAM A. , AHMED B.
Published: July 2006

Concentration of inositol phosphates, phospholipids, and RNA and its derivatives of ten Bangladesh soils varied between 17.5 and 150 ppm, 0.5 and 11.0 ppm, and 0.22 and 1.30 ppm respectively. Variation in inositol phosphates was related to total phosphate and organic phosphate contents. Variation in phospholipids was associated with total phosphate, organic phosphate, and organic matter contents whereas the variation in RNA and its derivatives was related to total phosphate contents of the soils. Maximum mineralization of inositol phosphates was obtained in the first 30 days either when incubated with lime or when submerged under water. A moderate rate was observed in the subsequent 30‐day incubation periods. The mineralization was greater in soil which contained more organic matter and inositol phosphates. Mineralization also increased with pH. Liming enhanced mineralization as it induced conditions for the proliferation of phosphate transforming organisms.
INTERACTION OF BTPYRIDYLIUM HERBICIDES WITH ORGANO‐CLAY COMPLEX
Authors: KHAN S. U.
Published: July 2006

The adsorption of diquat (1,1′‐ethylene‐2,2′‐bipyridylium dibromide) and paraquat (1, 1′‐dimethyl‐4,4′‐dipyridylium dichloride) by an organo‐clay complex has been investigated. Paraquat was adsorbed by the organo‐clay complex in greater amounts than was diquat. Infrared studies suggest the formation of charge‐transfer complexes between diquat or paraquat and the organo‐clay complex. Organic matter upon interaction with clay may facilitate the adsorption of diquat and paraquat on clay minerals in soil.
STUDIES ON SOIL COPPER
Authors: McLAREN R. G. , CRAWFORD D. V.
Published: July 2006

Adsorption isotherms were determined for the specific adsorption of copper by soils and soil constituents. Adsorption was found to conform to the Langmuir equation. The Langmuir constants, a (adsorption maximum) and b (bonding term), were calculated. Soils were found to have specific adsorption maxima at pH 5.5 of between 340 and 5780 μg g−1, and a multiple regression analysis revealed that organic matter and free manganese oxides were the dominant constituents contributing towards specific adsorption. Adsorption maxima for soil constituents followed the order manganese oxides > organic matter > iron oxides > clay minerals, which supported the findings for whole soils.

The cation exchange capacities (non‐specific adsorption) of the test soils were found to be far greater than the specific adsorption maxima. However, evidence suggests that, for the relatively small amounts of copper normally present in soils, specific adsorption is the more important process in controlling the concentration of copper in the soil solution.
STUDIES OF SOIL ORGANO‐MINERAL FRACTIONS
Authors: WATSON J. R. , PARSONS J. W.
Published: July 2006

Sand‐, silt‐, and clay‐size organo‐mineral fractions were isolated in bulk from surface horizons of five soils following ultrasonic dispersion in water. Good clay separation was achieved for all except one highly organic, calcareous clay soil. Organic‐N and ‐C were concentrated in the clay and silt fractions but for each soil the organic C : N ratio decreased in the order sand > silt > whole soil > clay. Acid hydrolysis of the silt and clay fractions revealed a slight concentration of amino acid‐N and NH4‐N in the clays but only small differences in the distribution of individual amino acids were observed. The results suggest that both silt and clay fractions may be important in the stabilization of soil organic matter.
STUDIES OF SOIL ORGANO‐MINERAL FRACTIONS
Authors: WATSON J. R. , PARSONS J. W.
Published: July 2006

Organ‐mineral particle‐size fractions, isolated from five soils by ultrasonic dispersion in water, were extracted with anhydrous formic acid/acetylacetone before and after treatment with aqueous HF partially to destroy silicate material. The resulting residues from two of the clay fractions, one montmorillonitic the other kaolinitic, were extracted further using the same reagents and also with 0.5M NaOH. The pattern of nitrogen extraction and nitrogen distribution data for the size fractions of four soils was similar but those of a fifth soil, with a high content of amorphous oxides, were quite different. There was evidence that the increasing nitrogen contents of successive samples of extracted material were mainly due to an increased amino acid content, especially dibasic acids. A serial extraction of clay fractions using formic acid/acetylacetone followed by HF followed by formic acid/acetylacetone and finally NaOH dissolved approximately 90 per cent of the organic‐N.
A RELATIONSHIP BETWEEN PHOSPHORUS REQUIREMENT, THE IMMOBILIZATION OF ADDED PHOSPHATE, AND THE PHOSPHATE BUFFERING CAPACITY OF COLLIERY SHALES
Authors: FITTER A. H.
Published: July 2006

Soluble phosphorus was allowed to age in contact with four colliery shales for up to 6 months. The ageing process apparently involved three stages–(i) a rapid initial drop controlled by pH; (ii) a steady‐state period; and (iii) an exponential decline whose rate was proportional to buffering capacity. Using this relation‐ship a model was derived to predict soil phosphorus requirement.
MINERALOGY AND GENESIS OF CLAYS IN RED‐BLACK SOIL TOPOSEQUENCES ON BASIC IGNEOUS ROCKS IN KENYA
Authors: KANTOR W. , SCHWERTMANN U.
Published: July 2006

The clay mineralogy of two red‐black soil toposequences on basic igneous rocks in Kenya has been investigated. Besides some illite and amorphous material kaolinites predominate in the slope soils (ultisols) whereas smectites are the main clay minerals in the soils of the depressions (vertisols). The kaolinites are poorly crystalline and have high surface area. According to chemical analysis, IR spectroscopy, and D.T.A. the smectites appear to be a ferriferous member of the montmorillonite‐beidellite series having approximately 0·5 Fe3+ in octahedral and 0·2 Al per O10(OH)2 in the tetrahedral position. The profile and slope distribution of kaolinites and smectites led to the conclusion that the smectites are the first weathering product and, depending on hydrological conditions governing the soil solution composition (Si, Mg, pH), either persist (depression) or are decomposed (slope) and followed by kaolinites.
GENESIS OF RED AND BLACK SOILS ON BASALT ON THE DARLING DOWNS, QUEENSLAND, AUSTRALIA
Authors: BECKMANN G. G. , THOMPSON C. H. , HUBBLE G. D.
Published: July 2006

Shallow friable red soils (euchrozems) and shallow cracking clays (black earths) occur in close proximity on basalt hills of the Darling Downs of Queensland. The euchrozems are mainly restricted to fiat hill crests and are associated with lithosols; the shallow black earths occur on upper pediment slopes, on small convex crests and on depressions on flat crests. The euchrozems are moderately leached and contain kaolin minerals and hematite with minor montmorillonite, while the black earths are dominantly montmorillonite with minor kaolin and hematite. It is proposed that the euchrozems have developed by long continued weathering under stable well‐drained conditions while the black earths have formed in sites prone to erosion and in situations with less water available for weathering. The weathering products produced in each situation have ensured continuation of the processes. The presence of two red soils in anomalous positions have been ascribed to (a) soil formation on exposed ‘bole’ (compacted red clay) layers and (b) local peculiarities of parent material controlling the course of weathering.
CHARACTERISTICS OF NUBIAN SANDSTONE‐DERIVED SOILS
Authors: SINGER A. , AMIEL A. J.
Published: July 2006

Nubian sandstone exposures in sub‐humid, semi‐arid, and arid environments have given rise to red, sandy but in other respects very different soils. Soils have a fairly well developed profile only in the sub‐humid zone, including a textural B horizon and are free of soluble salts and carbonates. In the semi‐arid and arid zones, profile differentiation is weak or non‐existent. Soils are shallow and contain carbonates, and in the arid zone also soluble salts, including gypsum. Kaolinite is the only clay mineral which is common to all the nubian sandstone parent materials. It is the major clay mineral in the sub‐humid zone soil. In the semi‐arid soils smectite is a second major clay component. In the arid zone both smectite and palygorskite, in minor amounts, accompany kaolinite. Both smectite and palygorskite are probably pedogenic neoformation products. Material of aeolian origin has probably been introduced into the silt and fine sand fractions of both the semi‐arid and arid soils. Some contamination of the clay fractions may have also occurred.
KINETICS OF ION EXCHANGE IN SOIL ORGANIC MATTER
Authors: BUNZL KURT
Published: July 2006

The rate of ion exchange of humic substances (humic acid and peat in the hydrogen form) with lead ions was investigated. As in processes occurring in nature, the lead solution was added in all our experiments slowly and continuously at a constant feed rate to the well‐stirred water‐suspended humic substances. Control experiments were also performed with a well‐defined synthetic ion‐ exchange resin (carboxylic acid type). The uptake of divalent lead ions by the humic substance and by the ion‐exchange resin, which is coupled with the release of an equivalent amount of hydrogen ions, proceeds as a function of time according to a characteristic sigmoidal curve. During the initial phase, the rate of ion exchange increases continuously with time, even though the humic substances become more saturated with lead ions.

Theoretical calculations, based on a film diffusion process as the rate‐determining step, show that this behaviour should indeed be observed if any solution, containing exchangeable counter ions, is added continuously to an ion exchanger suspended in a solvent.

The theory predicts further, in agreement with the experimental results, that in the initial phase of the ion‐exchange reaction, the uptake of the counter ions is proportional to the square of the time. If experiments are performed with different rates of addition of the counter ions, the time required to exchange a certain amount of counter ions should be proportional to α‐1/2, where α is the rate at which the ions are added. This prediction is also in accordance with the experimental results.
THE CALCAREOUS SOILS OF AZERBAIJAN.
Authors: ABEDI M. J. , TALIBUDEEN O.
Published: July 2006

The surface properties of soil carbonate were related to its distribution in thirteen profiles of a catenary sequence of calcareous soils from Azerbaijan.

When carbonate surfaces were contaminated by Mg2+, 45Ca was used as a tracer for Mg2+ as well as Ca2+, thus enabling the carbonate surface areas to be estimated. These were shown to be inversely and curvilinearly related to soil carbonate contents, but with some abnormality for the three extremely saline/alkaline soils. Na+ does not appear to be specifically adsorbed on carbonate surfaces in the latter.

The specific and the total surface areas of carbonate in the surface soils are very sensitive indices of profile development, and are combined with the content and particle‐size distribution of carbonate in the profiles to show the variation in soil development along the catenary sequence.