bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE APPLICATION OF SOIL MICROMORPHOLOGY TO FOSSIL SOILS AND OTHER DEPOSITS FROM ARCHAEOLOGICAL SITES
Authors: DALRYMPLE J. B. 
Published: July 2006

SummaryIn archaeological sites of Pleistocene and Postglacial age fossil soil horizons may be buried or form part of a composite soil profile when they may be either degraded or relic in nature. Since the A horizons of soils may be identified by their humus forms and the B horizon by their fabrics, both immature and mature fossil soil horizons may be identified and distinguished from man‐made deposits such as occupation layers and ditch fillings. Thus, micromorphology can be used as a geochronological technique for supplementing the existing knowledge of the mild and cold phases of the Pleistocene and to a lesser extent of the Postglacial.In mature fossil soils, since the fabrics of many B horizons are characteristic of certain soil types and are not altered by colluvial activity, it is possible to deduce something of the physiographic environment under which such fossil soil horizons were formed and, in particular, of the climate at the time of their formation. Thus, from composite soil profiles in archeological sections, relic fabrics have been observed and the primary origin of such colluvially derived soil material deduced. From buried profiles in loess sections of Europe the occurrence of braunerde fabrics with sol‐lessivé features confirms the other lines of evidence which suggest that the mild phases of the Pleistocene had similar climatic conditions and that these differ from those of today in the same area only in that the summers are today somewhat cooler and weetter.
CLAY MINERALOGY OF SOME AUSTRALIAN RED‐BROWN EARTHS
Authors: RADOSLOVICH E. W. 
Published: July 2006

SummaryThe clay mineralogy of Australian red‐brown earths has been investigated by X‐ray diffraction techniques supported by chemical analyses.A brief description of the morphology of this group of soils is given, and their geographical distribution indicated. Profiles have been studied from each of the major areas in which red‐brown earths are found.A large number of samples were examined by X‐ray diffraction. The results showed relatively little variation in clay mineralogy from one profile to another, or from one horizon to another within a profile. The dominant clay minerals in typical red‐brown earths in southern Australia are illite and kaolin, but in Queensland kaolin predominates.Chemical data (cation‐exchange capacity, SiO2: Al203 ratio) are consistent with the X‐ray results. There is evidence, however, that the illites in these soils are deficient in structural potassium, having K contents between 2.5 and 4.1 percent. K approximately. There is a consequent increase in the exchange capacity of these‘degraded’ illites.The variations in the clay mineralogy of these soils appear to depend mainly on the parent materials from which the soils are derived. Those red‐brown earths developed on alluvial and similar materials contain more illite than kaolin; those soils developed on materials such as granite, granodiorite, and basalt contain mainly kaolin in the clay fraction.
AN EXAMINATION OF THE METHOD OF AGGREGATE ANALYSIS BY WET SIEVING IN RELATION TO THE INFLUENCE OF DIVERSE LEYS ON ARABLE SOILS
Authors: CLEMENT C. R. , WILLIAMS T. E. 
Published: July 2006

SummaryWet sieving as a measure of the effect of leys on crumb stability is discussed, briefly nothing the significant details of sampling and analysis.The increase in water‐stable aggregation following several ryegrass/white clover leys of four years duration was of the same magnitude for both clay and sandy loam soils. The lighter soil, having the lower initial stability, showed the greater proportionate increase. Perennial rycgrass/white clover swards were consistent in giving higher values for water‐stable aggregation than other commonly sown grasses. It would seem that a large proportion of clover in a sward would not impair the stabilizing effect of a ley. There was no evidence of any significant variation resulting from different methods of grassland utilization. Data from Hurley soil suggest that intensive grazing did not reduce the effect of the grass ley on soil stability as long as a plant cover was maintained. Cocksfoot sown in drills for seed production had less effect on the soil than did swards of this grass sown with white clover. The application of nitro‐chalk to grass leys over a three year period at annual rates up to 16 cwt. per acre had no significant effect on either of the soils examined. Profiles to 1 ft. depth showed that, whereas the high stability found under permanent pasture extended throughout this profile, the increase in water‐stable aggregation under a three‐year ley was largely confined to the top few centimetres.
NITROGEN STUDIES ON THE IRRIGATED SOILS OF THE SUDAN GEZIRA II. EXTENDED FALLOWING IN COTTON ROTATIONS
Authors: JONES T. A. 
Published: July 2006

SummarySeasonal fluctuations in organic nitrogen and nitrate nitrogen in the soil of the Sudan Gezira are described under conditions of extended fallowing in cotton rotations. Statistically, results show that soil organic nitrogen is independent of rotational phase. Cotton yields are not limited by the content of organic nitrogen in the soil, but by soil physical conditions which improve by extended fallowing. Evidence is presented to show that soil organic nitrogen and nitrate nitrogen in this soil do not function in close interdependence. This conclusion was drawn in other work previously published.
A STUDY OF CARBON‐NITROGEN RATIOS ON THE IRRIGATED SOILS OF THE SUDAN GEZIRA
Authors: JONES T. A. 
Published: July 2006

SummaryThe seasonal fluctuations and rotational differences in carbon‐nitrogen ratios are reported under irrigated rotational cropping in the Sudan Gezira. Statistical analysis shows that there are no rotational differences in carbon‐nitrogen ratios.Seasonal fluctuations in the ratio reflect the cropping period in the rotation and also display marked activity during the period of the year when it is very hot and dry.
STUDIES ON THE BASALTIC SOILS OF NORTHERN IRELAND
Authors: McALEESE D. M. 
Published: July 2006

SummaryThe fine sand separates (0.02–0.2 mm.) from five basaltic soil profiles have considerable cation‐exchange capacities (C.E.C.) ranging from 16.5 to 31.4 m.e. per cent. Only a small part of the C.E.E. is due to clay minerals (diameter > 2μ) cemented into aggregates of fine‐sand dimensions by free sesquioxides.Mineralogical studies of the fractions obtained, after separation by the bromoform technique, show all heavy mineral groups (s.g. > 2.85) to have a high content of pyroxenes (principally augite) followed by the opaque minerals (mainly magnetite). The heavy groups have small C.E.C., i.e. < 7.5 m.e. per cent., as expected from the mineralogical composition.In the light fractions (s.g. < 2.85) which account for 57–80 per cent. of the total fine‐sand separates, quartz predominates in fractions from surface horizons of the profiles. In the lower horizons where quartz is less abundant, greenish‐yellow particles (pseudo‐aggregates) predominate and comprise over 45 per cent. of the light fractions. Whilst zeolites occur only in negligible amounts and feldspars do not represent more than 10 per cent. of the light fractions, yet the C.E.C. of these fractions are considerable, ranging from 41.7 to 72.4 m.e. per cent. Refractive‐index measurement and colour indicate that the pseudo‐aggregates are mainly chlorites. They must be individual particles, since prolonged reduction failed to cause any further disruption.The calculated values for the C.E.C. of the pseudo‐aggregates range from 90 to 110 m.e. per cent.; the same order of magnitude as that for vermiculite and montmorillonite.X‐ray photographs of the isolated pseudo‐aggregates from three fine sands show that the particles are of two types: (a) principally vermiculitic under good drainage conditions, (b) principally montmorillonitic where the drainage conditions are poor. Chlorites could not be detected, but there was a small amount of kaolinite and some amorphous material.It is suggested that the pseudo‐aggregates are individual particles representing an intermediate stage in the weathering of ferromagnesian rocks to the clay minerals, vermiculite or montmorillonite.The high C.E.C. of the fine sands are due to (i) a small contribution from clay minerals (diameter < 2μ) present in the fine sands as the result of aggregation and cementation by free sesquioxides, and (ii) a major contribution from the pseudo‐aggregates, which have C.E.C. between 90 and 11O m.e. per cent.
THE NATURE OF THE DRAIN CHANNEL AS A FACTOR IN THE DESIGN OF A LAND‐DRAINAGE SYSTEM
Authors: CHILDS E. C. , YOUNGS E. G. 
Published: July 2006

SummaryDrainage theory is customarily discussed on the assumption that the drainage channel is uniformly permeable. In practice such channels often consist of short lengths of relatively impermeable pipe separated by gaps. It is shown here that the appropriate modification to the theory in order to embrace such channels is to substitute an equivalent permeable channel of smaller radius.Experiments described here enable one to evaluate the equivalent drain radius, and show that this radius is not solely dependent upon the geometry of the gappy channel but is markedly affected by the ratio of intensity of rainfall to soil hydraulic conductivity. In the examples shown a tenfold increase of rainfall rate causes a hundredfold increase of effective drain radius.
A TREATMENT OF THE CAPILLARY FRINGE IN THE THEORY OF DRAINAGE
Authors: CHILDS E. C. 
Published: July 2006

SummaryThe hodograph treatment of the problem of drain design, as developed by van Deemter, is suitably modified to take into account the presence of a capillary fringe above the water table. Examples are presented to show that the presence of the fringe requires an increase of optimum drain size, and that thick fringes are accommodated mostly above a water table which is not proportionately much depressed below that which is appropriate to an absence of fringe, while thin fringes are accommodated in approximately equal proportions above and below the level of the fringeless water table.
A TWO‐CYCLE THEORY OF TROPICAL PEDOLOGY
Authors: OLLIER C. D. 
Published: July 2006

SummaryEvidence from geomorphology and mineralogy is presented which indicates that many tropical soils in Uganda are formed on pre‐weathered rock. The first cycle of weathering took place before the formation of the African surface, probably in Mid‐Tertiary times or earlier. Further weathering and pedological change is taking place in the present cycle.A variety of profiles are explained on this basis and some catenary relationships are also described. A number of previous ideas are discussed to indicate how the present theory differs from earlier ones.
GENERALIZATIONS ON SOME TANGANYIKA SOIL DATA
Authors: CALTON W. E. 
Published: July 2006

SummaryData on a number of Tanganyika soils are studied in regard to their origins and fertility improvement. Significant differences are shown between the various groups of soils and their clay type is deduced. Cation saturation adjustment—or the controlled addition of Ca, Mg, and K to give saturations for the particular colloid complex optimal for plant growth—is put forward as a new and practicable means of markedly and permanently improving the fertility of highly leached tropical soils.
THE STRUCTURE OF SOIL CRUMBS
Authors: EMERSON W. W. 
Published: July 2006

SummaryA model of a soil crumb is proposed in which the crumb consists of domains of orientated clay and quartz particles. A clay domain is defined as a group of clay crystals which are orientated and sufficiently close together to behave in water as a single unit. In normal agricultural soils, where calcium is the dominant exchangeable cation, the clay crystals in the crumbs are all aggregated into domains by drying. Drying to the wilting point is apparently sufficient. In the model the domains and the quartz particles may be linked to each other by organic matter or soil conditioners. The domains may also be held together by electrostatic forces. The model satisfies four conditions derived from experiment on the effect of organic matter on soil crumbs:

The crystalline swelling of the clay in the crumb is unaltered—the individual crystals within the domains are unaffected by organic matter and are free to take up water.
Slaking is prevented—the strains set up in the crumb on wetting are shared between several domains through their common linkages by organic matter to quartz particles.
Dispersion of Na‐saturated crumbs is prevented—the linkages of the domains by organic matter restrain the diffuse double layer swelling of the clay.
pF—moisture content curve is unaltered—the stabilization by organic matter does not require a rearrangement of the structure of the crumb.

On the basis of the model, conventional wet‐Sieving or dispersion tests assess the strength of the organic‐matter linkages. Remoulding crumbs breaks many of the Previously Stable quartz‐domain bonds, so that on drying and re‐testing the stability of the crumbs has decreased.The model has been shown to be consistent with present knowledge of the action of cement and h e in stabilizing soil, cement or lime being substituted for organic matter in the model. It also accounts qualitatively for the sensitivity of Soils, that is the decrease in shear strength after remoulding. On the basis of the model the amount of organic matter resistant to microbial attack should be proportional to the surface area of the clay domains. Remoulding soil (or tillage) by breaking the organic‐matter bonds joining the clay domains to the quartz will free organic matter for microbial attack.This model does not apply to soil crumbs in which the crystalline swelling of the clay is prevented, for example by heat treatment.
CUTANS: THEIR DEFINITION, RECOGNITION, AND INTERPRETATION
Authors: BREWER R. 
Published: July 2006

SummaryThe term cutans is proposed for a broad group of pedological features, including so‐called‘clay skins’, associated with the surfaces of the skeleton grains, peds, and various kinds of voids within soil materials. The chief differentiating characteristics of cutans are the kind of surface with which they are associated, the mineralogical nature of the cutanic material, and the fabric of the cutans themselves. Cutans can be interpreted on the basis of their characteristics in terms of the genetic processes of soil formation, and classified into simple and compound groups, each of which can be sub‐divided into illuviation, diffusion, and stress types, composed of particular materials. The effects of cutans on profile development and plant growth may be considerable and their characteristics may dominate the characteristics of the soil material.
CARBON, NITROGEN, SULPHUR, AND PHOSPHORUS IN SOME SCOTTISH SOILS
Authors: WILLIAMS C. H. , WILLIAMS E. G. , SCOTT N. M. 
Published: July 2006

SummaryAn examination has been made of carbon, nitrogen, sulphur, and phosphorus relationships in ten surface soils from each of five parent‐material groups (calcareous, granite, slate, Old Red Sandstone, basic igneous) in North Scotland. Except that the calcareous soils contain about 40 per cent. less organic carbon, there are no significant differences in the mean contents of total nitrogen and organic carbon. These are highly correlated, but the C: N ratio varies inversely with the base status of the parent material, ranging from 11·3 in the calcareous group to 17·0 for the granite soils.The total sulphur content is very similar for the four non‐calcareous groups, but much higher in the calcareous soils, due to the presence of varying amounts of water‐insoluble sulphate, closely related to the calcium carbonate content. Small proportions of this sulphate may be combined with barium and strontium, but most of it is probably present as a co‐crystallized impurity in the calcium carbonate. There is a close overall relationship between total sulphur, nitrogen, and organic carbon in the non‐calcareous soils and a similar relationship for nonsulphate sulphur in the calcareous group, giving a mean C:N:S ratio of 140: 10: 1·4 for the five groups. This is similar to ratios from other countries, indicating the general importance of sulphur in soil organic matter.The organic phosphorus is highest in the basic igneous group and lowest in the calcareous soils, where it comprises 40 per cent. of the total phosphorus compared with 52‐61 per cent. in the non‐calcareous groups. The proportion of organic phosphorus to the other elements is about 50 per cent. less in the calcareous group, the mean C: N: S: P ratio being 113:10:1·3 :1·3, compared with 147: 10:1·4: 2·5 for the non‐calcareous soils. Probably due partly to varying accumulation of inositol phosphates and other resistant forms, the correlations of organic phosphorus with carbon and nitrogen are much lower than for sulphur, and it appears to be a less integral part of the organic matter.
CHANGES IN LEAF LITTER WHEN PLACED ON THE SURFACE OF SOILS WITH CONTRASTING HUMUS TYPES
Authors: GILBERT O. , BOCOCK K. L. 
Published: July 2006

SummaryDifferent trends have been demonstrated in the changes in composition taking place in sub‐samples of the same ash litter placed in nylon hair‐nets on neighbouring sites with mull and moder‐type humus forms. Similar trends have been shown to occur for oak litter and ash litter placed on the same moder site. The percentage nitrogen content of ash litter on the mull site remains virtually constant during the first 7 months of decomposition whereas on the moder site the content increases steadily for both ash litter and oak litter. The nitrogen content of oak litter is increased by considerable addition from outside. Possible sources of this additional nitrogen are considered. Extraction with hot water of litter at different stages of decomposition shows that the initially large water‐soluble fraction, which is poor in nitrogen, is leached out more quickly from ash than from oak litter.
POLYPHENOLS IN PLANT, HUMUS, AND SOIL
Authors: COULSON C. B. , DAVIES R. I. , LEWIS D. A. 
Published: July 2006

SummaryThe polyphenols of fresh green and dried leaves, litter, and superficial humus from mull and mor sites were examined by paper chromatography and paper electrophoresis. The greatest diversity and quantity of phenolic substances obtained in the extract of the fresh beech leaves from the mor site. There was a change in quantity of simple polyphenols grading from a maximum in fresh growing green leaves, falling through senescent leaves to dead leaves to fresh fallen leaves, to a minimum in decayed leaves and humus or stored dry leaves. Tannin stripping and especially hydrolysis and reduction of the decayed leaves and superficial humus released polyphenolic substances. The role of polyphenols in mull and mor formation is discussed.
POLYPHENOLS IN PLANT, HUMUS, AND SOIL
Authors: COULSON C. B. , DAVIES R. I. , LEWIS D. A. 
Published: July 2006

SummaryThe two pure polyphenols, D‐ and epi‐catechin, known to be present in the fresh green leaves of a number of tree species, have been shown to be capable of reducing ferric iron, in the form of hydrated ferric oxide, to an organic ferrous complex and solubilizing it in much the same way as do Bloomfield's leaf extracts. These polyphenols can remove iron, even when held firmly as in Triassic sand, and transport it as ferrous iron at low pH. Model soils, consisting of alumina and diatomaceous earth impregnated with ferric chloride, were treated with catechin solutions and fresh green‐leaf extracts. Both produced dark coloured bands in which substantial amounts of ferric iron had been converted to ferrous iron. Extracts of green beech leaves from a mor site were more effective than those from a mull site (June leaf collection). Extracts of humus and litter were singularly low in reducing and iron‐complex‐forming substances, corresponding to their low free polyphenol status.The illuvial horizon of a podzol formed on Barton sand has yielded organic matter on extraction with acetyl acetone. This contained much material of polyphenol origin associated with iron.The role of polyphenol activity towards iron is discussed in relation to podzolic and other soils.
TREE PATTERNS IN THE SUDAN
Authors: WORRALL G. A. 
Published: July 2006

SummaryBands of acacia trees rhythmically disposed occur in the Sudan in a form resembling grass patterns. They have been found only on the red sand belt of Western Sudan, and aerial and ground observations and measurements seem to indicate that they all lie on gentle slopes very roughly on the contour, that they are as much as zoo m. wide with similar or wider spaces between them usually occupied by ground patchily covered by grass.Though sometimes tree bands may have a man‐made origin, the cause is generally natural and is probably the same as that producing grass patterns.
THE RED EARTHS AND THE COLLOIDS OF THE RED EARTHS
Authors: LISANTI LUIGI ENRICO 
Published: July 2006

SummaryThe chemical composition of the soils and of the colloidal separates of twelve red earths from three widely differing locations in Italy has been determined. The red earths of southern Italy are characterized by low organic matter, little if any CaCO3, and appreciable quantities of soluble salts. Those of northern Italy have opposite characteristics. The SiO2/R2O3 ratios of the colloids range from 1.60 to 2.09 and bear no relationship to location or climatic factors.It is concluded that similar pedogenetic processes have occurred throughout the Italian peninsula and are independent of geographical position or climatic conditions. In particular the SiO2/R2O3 ratio of the colloids of the southern soils is not unusually low as has been suggested by other workers.
THE LATERITIC SOILS OF THE SOUTH‐EASTERN PORTION OF THE AUSTRALIAN ARID ZONE
Authors: JESSUP R. W. 
Published: July 2006

SummaryRemnants occur in arid Australia of a formerly extensive land surface on which deep lateritic soils were developed. The lateritic profile, which contained silicified layers in the upper portion of the pallid zone, was subsequently truncated and water‐transported deposits containing lateritic detritus were laid down over the exposed mottled or pallid zones. Silicification of the upper portions of these deposits resulted in the formation of surface silcretes (the duricrust).The silcrete capping on the lateritic plateaux is overlain by either younger soils formed on deposits of wind‐transported materials, or by deposits of wind‐blown gypsite. Gypsum, leached from the latter, has accumulated in the mottled and pallid zones of the lateritic profile.
SOILS OF THE QUEEN ELIZABETH ISLANDS (CANADIAN ARCTIC)
Authors: McMILLAN N. J. 
Published: July 2006

SummaryA geological reconnaissance of the northernmost group of islands of the Canadian Arctic (Queen Elizabeth Islands) afforded an opportunity to study the nature of the soils. Profile development is rare, and the nature of the soil surface mainly depends on the slope of the ground and the type of bedrock. Chemical weathering and plant action are almost negligible in the arctic environment. Three profiles were examined in detail, two in well‐drained positions and one probably water‐logged for most of the thaw period.It is concluded that soils of this area should properly be regarded as polar equivalents of lithosols and regosols and that they should not be classed with the Tundra Great Soil Group. The name Rawmark Great Soil Group is suggested to encompass such soils of polar environment both in the northern and southern hemispheres.