bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE PERCOLATION OF RAINWATER THROUGH SOIL DEMONSTRATED BY FLUORESCENT DYES
Authors: REYNOLDS E. R. C. 
Published: July 2006

SummaryTwelve 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

SummaryThe 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

SummaryInvestigation 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

SummarySeveral 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

SummaryThe 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

SummarySemi‐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

SummaryUsing 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

SummaryField 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

SummaryPotassium 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

SummaryIncreasing 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

SummaryConventional 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

SummaryPhysical 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

SummaryThe 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

SummaryA 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

SummaryZur'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

SummaryThe 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

SummaryMicromorphological 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

SummaryThe 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

SummaryThe 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

SummaryThe‘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

SummarySome 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.