bluuebunny/crossref_metadata_2025_split huggingface dataset:
PROBLEMS OF SOIL EVALUATION IN THE SUDAN
Authors: FINCK A. , OCHTMAN L.H.J. 
Published: July 2006

SummaryThe present soil evaluation of alluvial clay plains in the Sudan is a selective land classification for cotton cultivation under irrigation and based mainly on the sodium‐value concept. This Na‐value, being a corrected Na‐figure (Na: clay ratio), was developed and used for pre‐estimations of cotton yield levels. It is now shown that owing to its similarity with the exchangeable‐sodium‐percentage concept and to the fact that it does not generally give a satisfactory yield correlation the Na‐value has in practice been useful only for the exclusion of sodic soils.Reexamination of the Na‐value concept reveals that, instead of sodium value the clay content is a superior criterion for yield estimations. Cotton yield levels are positively correlated with clay contents of 40‐70 per cent. A new clay‐yield formula, Y =−49.3 + 2.57 X, where Y= per cent, relative yield and X = per cent. clay content of the 0‐40‐cm. layer, has been developed as a preliminary basis for the evaluation of cotton soils.
MECHANICAL COMPOSITION OF solODIZED solONETZ AND solONETZ‐LIKE1 SOILS OF SASKATCHEWAN2
Authors: JANZEN W. K. 
Published: July 2006

SummaryMedian values of pH, conductivity, organic and inorganic carbon, and mechanical analyses are reported for nine solodized solonetz soils and eight solonetz‐like soils. These data show that for solodized solonetz soils the A horizons are moderately acid, with the A2 and A3 horizons showing the greatest acidity. The B1 is neutral, and the lower B and C horizons are alkaline in reaction. The solonetz‐like profiles show a similar trend, but pH values are higher in the A horizons. Conductivity rises progressively from the A1 horizon downward in the solodized solonetz group, whereas in the solonetz‐like group the conductivity remains very low throughout.A regional Dark Brown prismatic profile is included for comparison.
THE PREPARATION AND STUDY OF THIN SECTIONS OF WET ORGANIC SOILS MATERIALS1
Authors: MACKENZIE A. F. , DAWSONZ J. E. 
Published: July 2006

SummaryThin sections of wet samples of disintegrated peats, sedimentary peats, and mucks were prepared in Carbowax 6000. Conventional methods of thin section preparation following freeze drying of the samples were not suitable for the study of organic soils because of organic matter shrinkage. Microscopic examination of Carbowax sections revealed numerous blobs of organic matter about 0.02 mm. in diameter in sedimentary peats. These blobs are presumably fecal pellets evacuated by small aquatic animals. Disintegrated peats contained variable amounts of plant fragments showing cellular structure. Muck soils were highly granulated, and the granules were small compared with the upper size limit of very fine sand.
DEFINING THE STATE OF REDUCTION OF A PADDY SOIL
Authors: JEFFERY J.W.O. 
Published: July 2006

SummaryThe empirical terms ‘oxidizing conditions’, ‘healthy reducing conditions’, and ‘extreme reducing conditions’ as they are applied to paddy soils are discussed. The expression rEh= Eh+ 0.180 pH is used to define these conditions more precisely, on the assumption that the presence of ferrous and ferric iron is necessary for healthy reducing conditions for rice. The concept may be useful in both well‐established and newly developing rice‐growing areas.
CHEMICAL STUDIES OF SOIL ORGANIC MATTER
Authors: TINSLEY JOSEPH , SALAM ABDUS 
Published: July 2006

SummaryExperiments with an untreated calcareous meadow soil containing 18 per cent. organic matter, and with the sodium soil prepared after treatment with dilute hydrochloric acid, have confirmed that sodium pyrophosphate, citrate, and oxalate solutions are good reagents for partial extraction of organic matter from soils, and have further demonstrated that sodium‐sulphite solution is as effective as pyrophosphate at comparable concentrations and pH values. Boiling for 1 hour with 0.5 N sodium pyrophosphate and sulphite solutions at pH 8.4 dissolved almost 40 per cent. of the organic nitrogen from the untreated soil, which is more than double the quantity dissolved by shaking for 24 hours at 18° C.
THE FATE OF solUBLE PHOSPHATE APPLIED TO SOILS
Authors: CHANG S. C. , CHU W. K. 
Published: July 2006

SummaryIt is commonly known that the soluble phosphate added to soils is largely changed into iron and aluminium phosphates in acid soils, and into calcium phosphate in calcareous soils. Recently Chang and Jackson (1957a) employed a method to fractionate the inorganic soil phosphorus into four principal forms, namely, aluminium phosphate, iron phosphate, calcium phosphate, and occluded phosphate, enabling more detailed examination of the fate of applied phosphate to be made using the method of Chang and Jackson (1958). The purpose of this investigation is to study the fixation and transformation of soluble phosphate added to soils of different characteristics under different conditions.
THE ADSORPTION OF CATIONS FROM solUTION BY ALLOPHANE IN RELATION TO THEIR EFFECTIVE SIZE
Authors: BIRRELL K. S. 
Published: July 2006

SummaryThe amounts of cation physically adsorbed from neutral‐salt solutions by allophane and co‐precipitated silica‐alumina mixtures are dependent upon the effective radius of the cation. For non‐hydrated cations, the B.E.T. theory indicates that about the same area of surface is covered by a monolayer of cations, the sizes of which may vary considerably. The results for hydrated cations are consistent with the idea of effective size as a factor in the mechanism of adsorption if the hydration numbers of Glueckauf are regarded as relevant to the process. When using leaching methods which allow the retention of most of the physically adsorbed cation (as is the case when alcohols are used to remove excess salt), cation‐exchange‐capacity values are in inverse order to the effective radii of the cations. This will apply to silica‐alumina catalysts as well as to soils containing allophane.
MEASURING THE STATE OF REDUCTION OF A WATERLOGGED SOIL
Authors: JEFFERY J.W.O. 
Published: July 2006

Summary Eh and pH measurements and the term rEh=Eh+3 × 2·3 RT/FpH have been tested under simulated field conditions and errors assigned to them. The author considers that, whilst Ehmeasurements in the field may be used to differentiate between reduced and oxidized soils, their error is too large for them to supply more precise information about the state of reduction of a waterlogged soil; he also considers that there is little point in adjusting these measurements for pH change.It is proposed that an estimation of the concentrations of the two states of iron in a waterlogged soil should be used as the basis of a field method for measuring the soil's state of reduction.The results give some support for the argument that the equation
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is applicable to waterlogged soils.
THE AVAILABLE‐WATER CAPACITY OF A SANDY LOAM SOIL
Authors: SALTER P. J. , HAWORTH F. 
Published: July 2006

SummaryTo assess the effects of cultural and manurial treatments on the available‐water capacity of a sandy loam soil it was necessary to determine the upper and lower limits of the available water.The results of determining the moisture content of the soil at field capacity (FC) by two methods have been compared. It has been found that the direct method involving soil sampling after irrigation and when drainage had almost ceased, gave more accurate and consistent results than the suction‐plate method using any single tension.With the soil which had received farmyard manure, the permanent wilting percentage (PWP) determined on undisturbed cores and on crushed samples of soil by the sunflower technique showed significant differences and for critical work the results of determinations made on soil cores were preferred. The desiccator method of determining PWP was found to be insufficiently accurate for use in this type of work.
AN INVESTIGATION OF THE PRESSURE‐MEMBRANE METHOD FOR MEASURING THE SUCTION PROPERTIES OF SOIL
Authors: COLEMAN J. D. , MARSH A. D. 
Published: July 2006

SummaryTwo new forms of pressure‐membrane apparatus are described. One has been developed for routine use, while the other has been used for pressure‐membrane tests at very high pressures (up to 1,500 atmospheres, or pF 6·2).For soil in both the wetting and drying condition it is shown that the relation between suction and moisture content determined by pressure‐membrane tests agrees with that obtained using the suction plate, the centrifuge, the vacuum desiccator, and the sorption balance. The rate of attainment of moisture equilibrium in the pressure membrane is also examined experimentally, for a very wide range of air pressures.
AN INCUBATION TECHNIQUE FOR ASSESSING THE NITROGEN STATUS OF SOILS NEWLY PLOUGHED FROM LEYS
Authors: CLEMENT C. R. , WILLIAMS T. E. 
Published: July 2006

SummaryA technique is discussed whereby the level of mineral nitrogen present in the soil after incubation has been used to estimate differences in the nitrogen status of an arable soil after leys. There was an appreciable increase in the mineralization of nitrogen in arable soil after 3 years under ley, despite any immobilization which may have resulted from the decomposition of grass roots. The uptake of nitrogen by the winter wheat which followed the leys was closely related to the nitrogen status of soil so determined.
HARDPAN IN SOILS OF SEMI‐ARID WESTERN AUSTRALIA
Authors: LITCHFIELD W. H. , MABBUTT J. A. 
Published: July 2006

SummaryHardpan cemented by silica occurs widely in semi‐arid Western Australia below a variety of soils, mainly at shallow depth but more deeply in more permeable soils.Strongly cemented hardpan is widespread on gentle alluvial slopes formed by partial destruction of a lateritized Tertiary land surface; it also occurs in sand plain on remnants of this surface, but occurs only locally in the saline alluvial plains in the lowest areas of interior drainage.Hardpan results from silica cementation and clay deposition. As suggested by Teakle (1936), it may be due to leaching following episodic sheet flooding. Its formation appears to have kept pace with deposition of alluvium, and continues at the present time. Irregularities in or absence of hardpan formation are shown to relate to changes of slope, local drainage, and to certain soils.
SOIL LAYERS ON HILLSLOPES: A STUDY AT NOWRA, N.S.W., AUSTRALIA
Authors: WALKER P. H. 
Published: July 2006

SummaryThree separate soil systems occur on hillslopes near the N.S.W. south coast. The proof of separateness lies in pedologic, stratigraphic, and geomorphological criteria by which the soil layers are shown to be independent entities.The sequence of soil layers is considered to be evidence of a K‐cycle soil history (after Butler, 1959) involving alternating stable and unstable conditions. Evidence suggests that K‐cycle instability (Ku) has resulted from a change to relatively dry climatic conditions and has involved processes such as hillwash, gully erosion, and soil creep; K‐cycle stability (Ks) is characterized by soil development during relatively humid phases. On the south coast the Minnamurra layer (minimal prairie soil) represents the youngest or Kl cycle; the Nowra layer (grey‐brown soils) represents the next oldest or K2 cycle; the Wandandian layers (red podzolic and yellow podzolic soils) represent the oldest or K3 cycle.
THE ADSORPTION OF INOSITOL PHOSPHATES AND GLYCEROPHOSPHATE BY SOIL CLAYS, CLAY MINERALS, AND HYDRATED SESQUIOXIDES IN ACID MEDIA
Authors: ANDERSON G. , ARLIDGE E. Z. 
Published: July 2006

SummaryA study has been made of the adsorption of inositol phosphates and β‐glycerophosphate by soil clays and minerals in a wide range of acid media.Of the adsorbents tested, the most active were boehmite, a soil clay with a high sesquioxide content, ferric oxide gel, and montmorillonite.Generally, in the case of the inositol phosphates, the higher the number of phosphate groups in the molecule, the greater was the degree of adsorption. There were exceptions in the case of some of the ferric hydroxide‐inositol phosphate systems.Adsorption of inositol hexaphosphate was favoured in two distinct acid media, at pH 3 to 4, and in acid of concentration about 0·1N. Montmorillonite was reactive at pH about 4, apparently owing to its content of active aluminium; X‐ray examination gave no indication that an ordered clay‐organic complex was formed. Montrnorillonite, kaolinite, and an illitic soil clay sorbed negligible amounts of the ester in strongly acid media. Ferric oxide gel removed considerable amounts of inositol hexaphosphate from strongly acid solution, presumably partly by adsorption, and partly by precipitation of insoluble salts or complexes of the ester. At pH 3 to 4 the gel was relatively ineffective, Boehmite was very reactive over a wide range of acid concentrations, from pH 4 down to concentrations of 4N with respect to hydrochloric acid; greatest sorption occurred at pH about 1. The sesquioxide rich soil clay had a high sorption capacity for inositol hexaphosphate in a wide range of acid concentrations. Removal of active iron and aluminium destroyed its activity at pH 4, but the clay was still reactive at pH 1.Inositol mono‐, di‐, and triphosphates were adsorbed by boehmite to a greater extent in IN HCl than in 0·1N HCl. This was true also of β‐glycerophosphate which was sorbed to a greater extent at pH 2·4, and in IN HCl than in 0·1N HCl.The adsorption of phosphate esters in equivalent concentrations of hydrochloric and sulphuric acids was often markedly different.
THE CHARACTERISTICS AND GENESIS OF A FERRITIC BROWN EARTH
Authors: STORRIER R. R. , MUIR A. 
Published: July 2006

SummaryThe surface soil of the Banbury clay loam is a moderately to slightly acid, wellstructured, brown to reddish‐brown, clay loam. With depth both structure and texture become coarser; the lower (B) horizons are characterized by a stone line, probably resulting from frost action. The profile examined shows no evidence of contamination by extraneous material. Weathering has taken place in situ and the clay minerals are derived from the parent material.The sequence of soil formation appears to be: chemical weathering of the solid rock with the conversion of siderite and chamosite to goethite followed by physical breakdown of the rock and redistribution of iron among the different particle size fractions. The latter is caused by mobilization, translocation, and flocculation of iron oxide, particularly in the coarser clay fraction and most noticeably in the (B)2, horizon. Iron has also been lost from the soil.
THE MOISTURE PROFILE ABOVE A MOVING WATER TABLE
Authors: CHILDS E. C. , POULOVASSILIS A. 
Published: July 2006

SummaryIt is shown on theoretical grounds that the shape of the moisture profile about a moving water table depends upon both the rate of infiltration at the soil surface and the rate of rise or fall of the water table. The profile shape may be computed provided that the moisture characteristic and the dependence of the hydraulic conductivity of the material on moisture content are known, and also provided that if the water table should be falling its velocity should not exceed the value of dK/dc at the moisture content Cu, prevailing at the surface of infiltration, where the hydraulic conductivity, Ku is equal to the infiltration rate. Experiments are described and the results are presented to show agreement between observed and computed profiles when the limiting condition is satisfied, for various combinations of rate of infiltration and rate of fall of the water table. Even when the limitation is not satisfied fair agreement is found over much of the range of moisture content, the discrepancy where it occurs being in the expected sense.
COMPARATIVE WATER‐USE OF SOFTWOOD PLANTATIONS AND BAMBOO FOREST
Authors: PEREIRA H. C. , HOSEGOOD P. H. 
Published: July 2006

SummaryWater‐use of indigenous bamboo forest was compared with that of pine and cypress plantations, in an area where both evaporation and strongly seasonal rainfall have average annual totals of about 45 inches. Water‐use was determined by a combination of continuous soil‐moisture tension records with seasonal, well‐replicated soil samplings, to a depth of 6 ft. from 1948 to 1950 and 10 ft. from 1951 to 1961. Root bisects and profiles of physical properties of the soil are illustrated and the soil moisture tension profiles are summarized in a diagram.Continuous canopies of 120‐ft.‐high Radiata pine, 50‐ft.‐high Monterey cypress, 40‐ft.‐high bamboo thicket, and 20‐ft.‐high young Patula pine all used about the same amounts of water, which were approximately 90 per cent. of that evaporated from an open water surface. Tall woody weeds, which invaded clearings and young pine plantations before the latter had achieved closed canopies, proved equally effective in removing water. Water is saved over 2 to 3 years and soil‐moisture tensions remain low enough throughout the profile to permit recharge of groundwater when the felling and replanting are accomplished under conditions of clean cultivation.
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

SummaryFactorial 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

SummaryIn 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

SummaryA 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

SummaryThe 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

SummaryThe 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

SummaryThis 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.