bluuebunny/crossref_metadata_2025_split huggingface dataset:
INCIPIENT FAILURE OF SOIL AGGREGATES
Authors: QUIRK J. P. , PANBOKKE C. R. 
Published: July 2006

SummaryA comparison of the rate of wetting of aggregates taken from a virgin and continuously cultivated Red‐brown Earth has been made. The aggregates were placed on a glass sinter which was connected to a horizontal capillary. The rate of water uptake was obtained from the rate of meniscus travel as water was adsorbed from the sinter by the aggregates.When air‐dry (P/P0≊ 0·50) aggregates were wetted at 2 and 10 cm. water suction the cultivated aggregates wetted more rapidly than the virgin aggregates. At a suction of 30 cm. both groups of aggregates exhibited almost identical rates of wetting. The difference in the rate of wetting could not be attributed to differences in pore structure since both groups of aggregates had almost identical total porosity and clay content and furthermore showed extremely similar rates of wetting when wetted at a low suction with a non‐polar liquid. When aggregates from a virgin and cultivated soil were wetted slowly the pF‐water content relationship was very similar; it was therefore concluded that organic matter did not give rise to a finite contact angle for the water advancing into the virgin aggregates.Because the cultivated aggregates when wetted at 30 cm. and then at 2 cm. ion did suctnot slake when placed in water, whereas cultivated aggregates wetted directly to 2 cm. suction from the air‐dry condition slaked when placed in water, the phenomenon is described as incipient failure. When the cultivated aggregates are wetted at 2 cm. suction the work done by the rapid wetting causes planes of failure to be set up and the soil moves from an over‐consolidated condition to that represented by the n o d or virgin consolidation curve (Croney and Coleman, 1954). It is proposed that the organic matter in the virgin aggregates strengthens the pores against failure and so this material retains its initial pore structure. Mechanical strength measurements on virgin and cultivated aggregates support this hypothesis.
DEVELOPMENT OF HYDROMORPHIC HUMUS PODZOLS AND SOME NOTES ON THE CLASSIFICATION OF PODZOLS IN GENERAL
Authors: DAMMAN A. W. H. 
Published: July 2006

SummaryHydromorphic humus podzols can develop under submerged conditions as a result of internal water movement, and their development is by no means dependent on the occurrence of a water table which descends, periodically, below the B horizon. The basic difference between podzolization under anaerobic and aerobic conditions is stressed, and it is suggested that classification of the podzols be based in the first place on these two processes, using the humus content of the B horizon for a further subdivision. It is pointed out that the humus content of the B horizon is unsuitable for the primary subdivision since it is governed by a number of independent factors.
CRITERIA FOR CLASSIFYING TROPICAL SOILS BY AGE
Authors: WAMBEKE A. R. VAN 
Published: July 2006

SummaryThree soil properties are proposed as criteria for distinguishing tropical and equatorial soils according to the age of their parent materials. The criteria are structure, silt‐clay ratios, and percentage of weatherable minerals. Assessments thus made agree well and conform closely to assessments based on geomorphology in Central Africa.
TERRACE CHRONOLOGY AND SOIL FORMATION ON THE SOUTH COAST OF N.S.W.
Authors: WALKER P. H. 
Published: July 2006

SummaryCyclic terraces and their soils developed in steeply graded drainage areas and gently sloping floodplains at the same time as the K‐cycle soil layers in the adjacent hill country. The K3 sediments are by far the greatest in volume while the K2 and K1 sediments are progressively smaller in volume.Radiocarbon dates for four terrace sites show that the K3 cycle commenced 29,000 years ago, the K2 cycle 3,740 years ago, the K1 cycle 390 years ago, and the present epicycle of erosion K0 0‐120 years ago. These dates do not correlate with the dates of past climatic events proposed by other Australian workers. They do show, however, that the soils on the N. S.W. south coast are rarely older than late Pleistocene.
WATER‐SUCTION CURVES OF LARGE‐GRAINED AGGREGATES
Authors: NAAR J. , WYGAL R. J. 
Published: July 2006

SummaryWater‐suction curves of large‐grained aggregates, when obtained from small samples, often do not represent the true moisture characteristics of the material. Gravity segregation of the fluids within the sample may cause the average moisture content to vary significantly from the true value that might be obtained could the measured suction be applied uniformly. A method for correcting these curves was derived to interpret correctly experimental results on such aggregates.
COPPER‐DEFICIENT SOILS IN SOUTH‐EAST SCOTLAND
Authors: PURVES D. , RAGG J. M. 
Published: July 2006

SummaryThe copper‐deficiency condition in cereals known as‘wither‐tip’has been found in a limited area in south‐east Scotland during the past ten years. This condition has been consistently associated with a low level of total copper in the surface horizon.The distribution of‘wither‐tip’and low copper content is directly related to the presence of one soil type, namely Eckford series, within the fields in question.Analysis of IOO surface soils sampled in south‐east Scotland suggests that a substantial proportion of the fields in this region are copper deficient or potentially copper deficient.
THE SOILS OF ISRAEL AND THEIR DISTRIBUTION1
Authors: DAN JOEL , KOYUMDJISKY HANNA 
Published: July 2006

SummaryThe main soil groups present in Israel are listed, their geographic distribution is described and related to pedogenic factors. Three physiographic‐lithologic regions are recognized: the coastal region, the mountain and hill region, and the valleys, plains, and plateaux. Climate ranges from Mediterranean in the north to extremely arid in the south. Depending upon climatic conditions in each of the physiographic‐lithologic regions, climatogenic soils range from those characteristic of the Mediterranean region (noncalcic brown soils, terra rossa, brown rendzina, grumusols) in the north to desert soils (serozem, hammada) in the south.
THE EFFECT OF FARMYARD MANURE ON THE MOISTURE CHARACTERISTIC OF A SANDY LOAM SOIL
Authors: SALTER P. J. , WILLIAMS J. B. 
Published: July 2006

SummaryAnnual applications of farmyard manure for 7 or 8 years have led to a significant increase in the available‐water capacity of a sandy loam soil and in the volume of water released at low tensions. The available‐water capacity increased, and the moisture characteristic altered, as the soil became more compacted during crop growth in both 1960 and 1961, and differences in moisture characteristics between the manured and unmanured soil were greatest at the harvest time of the crop.
CALCULATION OF NEGATIVE AND POSITIVE ADSORPTION IN SOME CLAY ELECTROLYTE SYSTEMS
Authors: HELMY A. K. 
Published: July 2006

SummaryCalculations are presented of the fraction of charge compensated by cations for some clay systems. Surface charge density, electrolyte type, concentration and composition are studied in their relation to positive adsorption and exchange of cations in some clay systems. It is calculated that the negative adsorption due to mono‐valent anions is about one‐third that due to divalent ones present at the same concentration.
MECHANISMS OF FORMATION OF SODIUM CARBONATE IN SOILS
Authors: WHITTIG L. D. , JANITZKY P. 
Published: July 2006

SummaryMechanisms of formation and accumulation of Na2CO3 have been studied in a graded sequence of salt‐affected soils of the Sacramento Valley, California. The soils are confined within a drainageway which is inundated during winter with flood waters containing relatively low concentrations of neutral sodium, calcium, and magnesium salts. Heavy inundations and high water tables within the basin lead to microbiological reduction of sulfate and ferric iron. The resulting sulfide is held within the soil as FeS whereas the CO2 released by biological oxidation of abundant organic matter forms bicarbonate. Lateral and upward migration of bicarbonate‐charged water from the drainageway basin to soils nearer the basin rim results in yearly increases in concentration of soluble salts within these soils. Ca(HCO3)2 and Mg(HCO3)2 migrate from the zones of maximum CO2 production and precipitate as carbonates. NaHCO3 continues to move, along with the capillary water, and accumulates in the rim soils. As water evaporates or is used by growing plants, loss of CO2 from the NaHCO3 occurs, resulting in the formation of Na2CO3. The high Na2CO3 concentration at these rim positions has resulted in removal of divalent bases from the exchange complex, an equivalent increase in exchangeable sodium, and high pH.
STUDIES ON SOIL POTASSIUM
Authors: TINKER P. B. 
Published: July 2006

SummaryThe composition of the topsoil in Nigerian oil palm plantations is expected to be closely related to the potassium status of the palms. K‐(Ca±Mg) activity ratios obtained from the equilibrium solution data presented in Part III of this series were not related to potassium yield response in field experiments on highly acid soils. This conclusion is supported by the failure of liming to affect potassium response, though the equilibrium activity ratios of acid soils are strongly affected by it.A relationship was found between yield response and the K‐(Ca±Mg) activity ratios of the soils determined in presence of sufficient lime water to remove soluble aluminium.A better relationship was obtained between yield response and a ‘unified activity (K±) ratio’
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, called ARu, the activities being those found in the true equilibrium solutions. ARu was found to be far less dependent on exchangeable Ca±Mg than the K‐(Ca±Mg) activity ratio.
TOXICITY AS A CAUSE OF THE INEFFICIENCY OF UREA AS A FERTILIZER.
Authors: COURT M. N. , STEPHEN R. C. , WAID J. S. 
Published: July 2006

SummaryPlant damage and reduced yields were associated with delayed ammonification or nitrification of added urea‐nitrogen. In a neutral sandy loam, the adverse effects of urea application were associated with the accumulation of toxic levels of first ammonia and later nitrite. Addition of hydrogen‐ion as phosphoric or sulphuric acid alleviated the damage thereby supporting the conclusion that ammonia and nitrite accumulation were the causes of phytotoxicity. In an acid sand, toxicity was associated first with the presence of large quantities of urea remaining in the soil though the evidence was insufficient to show in what way the urea was toxic. There was then a second phase of toxicity associated with the presence of considerable quantities of ammonium‐nitrogen under conditions where toxic levels of ammonia were likely to have occurred. The later phase (nitrite toxicity) did not occur. Phytotoxicity arising from urea addition to the soil could be due apparently to the persistence of urea as such in the soil and also to the accumulation of significant quantities of free ammonia and nitrite. The occurrence of one or more of these phases of urea toxicity depended on differences in soil conditions.
SOILS OF THE ULTRA‐BASIC ROCKS OF THE ISLAND OF RHUM
Authors: RAGG J. M. , BALL D. F. 
Published: July 2006

SummaryUltra‐basic and basic igneous rocks outcrop as a complex over about 20 square miles of the island of Rhum, off the west coast of Scotland. Here in a cool wet oceanic climate, where the annual rainfall varies from 55 to 130 inches, there has developed a sequence of soils from rankers to peat podzols or braunerden. The development is not a simple time relationship at a particular site because of the existence of a complex erosion, transport, and deposition cycle. There is evidence for a previous long stable period succeeded by more intense erosion, possibly ascribable to past land‐use. The podzols differ from typical podzols in having no AB horizon, high pH values, and high contents of exchangeable cations, especially magnesium.
MECHANISMS OF FORMATION OF Na2CO3 IN SOILS
Authors: JANITZKY P. , WHITTIG L. D. 
Published: July 2006

SummaryBiological transformations have been responsible for formation of Na2CO3 and resultant high alkalinity in some of the salt‐affected soils of the Sacramento Valley, California. Environmental factors favouring Na2CO3 formation are high ground‐water level to provide an anaerobic environment, supply of Na2SO4, and organic matter. Under these conditions, anaerobic micro‐organisms reduce sulphate to sulphide and oxidize organic matter to CO2. The sulphides hydrolyse to produce free OH which combines with CO2 to form HCO3. Reduced Fe in the system inactivates the sulphides and allows accumulation of NaHCO2. Loss of CO2 from NaHCO2 during dry periods of the year results in formation of Na2CO3.In the laboratory an anaerobic environment and a supply of readily decomposable organic matter have been shown to be essential for development of HCO3 and CO3. Ultimate development of high alkalinity depends upon inactivation of soluble and exchangeable divalent bases as precipitated carbonates. Inactivation of divalent bases favours a high exchangeable Na content as well as build up of soluble NaHCO3 and Na2CO3.There is an equivalent relationship between the amount of SO4 reduced and HCO3 formed by the processes involved. The anaerobic organisms involved in the transformations obtain oxygen from the SO4 and in turn oxidize carbon of the organic matter to CO2.Development of HCO3 and CO3 is favoured in situations where organic matter and Na2SO4 concentrations are both high, but is limited in systems with a relatively low organic matter content and a high concentration of Na2SO44, or conversely, when a high content of organic matter is combined with a low salt concentration.
A PHYSICO‐CHEMICAL STUDY OF THE PROPERTIESOF HUMIC ACIDS AND THEIR CHANGES DURING HUMIFICATION
Authors: VISSER S. A. 
Published: July 2006

SummaryHumic acids extracted from decomposing plant and peat core samples and changes in them during the process of humification were investigated in terms of their elementary composition, the acidity and the equivalent weight, the infra‐red, visible and ultra‐violet spectra and the shape and size of the molecules and their weight. With progressive humification in peat and decomposing plant samples, increases were noted for the carbon content and the aromatic character of the humic‐acid molecules and in the number of their alcohol and ether groups, aliphatic side chains and double bonds, while decreases were observed for the hydrogen content, the molecular weight, the equivalent weight, and the hydrophilic character of the humic acids and possibly to a minor extent also for the ionization constant and the alkoxyl and alkimide groups. It was noticed that the presence of charcoal and, to a minor extent also, of clays in decomposing plant material promoted the formation of humic acids which were very similar to those found in older peat deposits, while the presence of ash did not seem to have much effect. Humic acids derived from different peat materials were found to be very similar in structure and composition, but when different types of plant material were mixed, the humic acids formed during the first stages of decomposition were very similar to those from more decomposed samples containing only the separate components.
A PRELIMINARY STUDY OF SOME SLOPE SOILS IN WALES AND THE WELSH BORDERLAND
Authors: MACKNEY D. , BURNHAM C. P. 
Published: July 2006

SummaryData are given concerning four profiles developed in materials of loam or clay‐loam texture, representative of soils found on moderate or steep slopes in Wales and the Welsh Borderland. Two acid well‐drained soils with A(B)C profiles are correlated with sols bruns acides, differences in soluble Fe2O3 content probably being the result of more intense weathering in districts of greater rainfall. A humus‐iron podzol described differs from typical profiles of this class in being finer in texture, and there is a significant divergence in micromorphology. The remaining soil is regarded as transitional because it has some properties of both classes. It has a prominent brown B horizon of redder hue than the overlying unbleached A horizon; organic carbon values are distinctly greater than for solsbruns acides, but there is no horizon of accumulation; SiO2/R2O3 ratios follow the pattern of variation typical of podzols though differences are less marked; the micromorphological characters of the B horizon are very similar to those of the Bs horizon of the humus‐iron podzol.
A CATENA OF SOILS ON THE NORTHERN RHODESIA PLATEAU
Authors: WEBSTER R. 
Published: July 2006

SummaryThe plateaux of Northern Rhodesia have a characteristic pattern of soils which, with variations, covers many thousands of square miles. A representative sequence of soils ranging downslope from red, through yellowish brown to grey is described. The soils are composed of material in an advanced stage of weathering and are shown to be developed more or less in situ from biotite gneiss. Redeposition of material once eroded is relatively unimportant. The colour sequence in this instance is attributed to the proportion of free iron oxides in the soil.
SLOPE DEVELOPMENT AND SOIL MORPHOLOGY IN A PART OF SOUTH‐WEST NIGERIA
Authors: MOSS R. P. 
Published: July 2006

SummaryThe soils of two cuestas developed on ferruginous sandstones, one of Cretaceous, and the other of Eocene/Pliocene age, were studied in relation to the slopes and planation surfaces with which they were associated. The processes involved in the retreat of hardened plinthite breakaways are shown to account for the principal morphological features of the soils, especially the lower diagnostic horizons, and thus throw light upon the mode of formation of the ‘Acid Sands’ of southern Nigeria, and the ‘terre de barre’ of the ‘Continental Terminal’ of southern Dahomey. A distinction is made between sheet plinthites and flanking plinthites according to their mode of occurrence, both being related to periods of stillstand in the evolution of the slopes.
A SURVEY OF ACTIVITIES OF ENZYMES HYDROLYSING SUCROSE AND STARCH IN SOILS UNDER PASTURE
Authors: ROSS D. J. 
Published: July 2006

SummarySome climatic and soil factors influencing the activities of enzymes hydrolysing sucrose and starch in New Zealand soils under pasture were studied.Amounts of reducing sugars produced on incubation of soils without added substrate were related very closely to soil organic C content.Activities of (a) enzymes hydrolysing sucrose and (b) enzymes hydrolysing starch decreased and increased, respectively, with increasing rainfall; the ratios (a)/(i) were highest in the driest groups of soils.Variations in annual rainfall and soil organic C together, but not separately, explained much of the variation in sucrose‐hydrolysing activities; these activities appeared to be related more to the composition than the amount of organic matter in a soil.Variations in activity of enzymes hydrolysing starch could be explained by variations in soil organic C, clay content, and, in some cases, other factors associated with different soil groups; these activities were increased by irrigation and reduced by drainage of soils.The activity of starch‐hydrolysing enzymes, compared with sucrose‐hydrolysing enzymes, was relatively greater under legumes than under grasses at the same site but could differ considerably at different sites. Activities also differed under forest and pasture at adjacent sites.
THE VOLUME AND POROSITY OF SOIL CRUMBS
Authors: CURRIE J. A. 
Published: July 2006

SummaryA simple and inexpensive apparatus (a test‐tube, burette, and pin) is described for measuring volumes by liquid displacement to an accuracy of greater than 0.5 per cent. This has been adapted to measure soil crumb porosities, εc, by saturating 3–4 g samples of crumbs with kerosene, measuring the weight of kerosene retained internally, then measuring their volume by displacement. Three estimates of crumb porosity from these measurements are compared. Experimental values range from εc= 0.205 for the headland of an arable field to εc= 0.351 for a permanent pasture. Crumb porosity is proposed as a measure of structural status for soils because it assesses the degree to which soil management has succeeded in holding the constituent primary particles apart from the positions of inherent closest packing that they would ultimately assume in an unstable soil. By comparison, the inter‐crumb porosity, εv, can be used as a measure of cultivation status. In the form expressed, these two porosities are related to the more frequently encountered total porosity εt by the relation

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A KINETIC APPROACH TO THE DESCRIPTION OF SOIL PHOSPHATE STATUS
Authors: COOKE I. J. 
Published: July 2006

SummaryA kinetic factor is used to describe soil phosphate status. It is supplementary to capacity and intensity factors which are essentially static factors.The rate of release of phosphate ions from the soil solid phase was measured by the use of an anion exchange resin and a numerical parameter assigned to the release rate. A highly significant correlation was found between this parameter and the uptake of phosphate by ryegrass from a wide range of soils.
THE INFLUENCE OF TEXTURE ON THE MOISTURE CHARACTERISTICS OF SOILS
Authors: SALTER P. J. , BERRY G. , WILLIAMS J. B. 
Published: July 2006

SummaryA quantitative assessment was made of the effect of the proportion of sand, silt, clay, and organic matter in twenty‐six soils on the available‐water capacities (AWC) of the soils. The AWC of a soil was negatively correlated with percentage coarse sand and positively correlated with the percentages of International fine sand (or American silt) and organic C. Using a regression equation, the AWC's of the soils were estimated from mechanical analysis data with a mean accuracy of ± 16 per cent of the mean AWC.
A SIMPLE AND RELIABLE TENSION TABLE
Authors: CLEMENT C. R. 
Published: July 2006

SummaryA tension table may be constructed from a Perspex tray ⅝ in. thick, approximately 12 in. wide and 19 in. long with 21 drainage channels. With a filter paper membrane, which gives rapid transmission of water and can be readily changed when contaminated it may be used to equilibrate 3–4 kg of moist soil overnight at suctions up to 100 cm of water. Several small samples may be handled at once by using small filter‐paper trays.
THE MINERALOGY OF THE CLAY FRACTION FROM BASALTIC SOILS IN THE GALILEE, ISRAEL
Authors: SINGER ARIEH 
Published: July 2006

SummaryThe mineralogy of the clay fraction from basaltic soils in the Galilee, Israel, has been studied by X‐ray and differential thermal analysis techniques, supplemented by electron‐micrographs and chemical determinations.The mineralogical composition of the clay was greatly influenced by the amount of rainfall. In SE Galilee, where rainfall is 400–550 mm/annum, the dominant clay mineral is montmorillonite, with kaolinite as the second most important component. With increasing rainfall the amount of montmorillonite in the clay falls, and the amount of amorphous oxides of Fe and Al increases. In N and NE Galilee, rainfall is 550–700 mm/annum and the major part of the clay is composed of kaolinite or halloysite, quartz, and amorphous oxides of Fe and Al. The decrease in the amount of montmorillonite with increasing rainfall is explained by decomposition to kaolinite and amorphous oxides.
THE MEASUREMENT AND MECHANISM OF ION DIFFUSION IN SOILS
Authors: VAIDYANATHAN L. V. , NYE P. H. 
Published: July 2006

SummaryThe diffusive flux of soil cations and anions to an absorbing surface may be measured by a simple, quick, and accurate method using ion exchange resin paper as a sink maintaining, initially, zero concentration of the diffusate at the soil surface.The quantity of ions diffusing from the soil of semi‐infinite thickness is directly proportional to the square root of the diffusion time until about half the counter‐ions originally on the resin have been exchanged. Values of average effective diffusion coefficients are calculated using this proportionality constant and the concentration of total exchangeable ions. The effect of the counter‐ions of the resin on soil‐ion flux is small but measurable.