bluuebunny/crossref_metadata_2025 huggingface dataset:
TURKISH FOREST SOILS
Authors: MITCHELL W. A. , IRMAK A.
Published: July 2006

An account of the distribution and botanical composition of Turkish forests is given along with analyses of some typical soil profiles. Extreme variations in climate have a strong influence on the country, and over large areas the low rainfall is a limiting factor for plant growth. The position is aggravated by soil erosion which has followed clearance of wood land. The result of mineralogical analyses of the clay fractions are discussed with reference to soil type, parent material, cation‐exchange capacity, drainage and productivity of the soils.
FEATURES OF SOME SEMI‐ARID SOILS IN THE DISTRICT OF KHARTOUM, SUDAN
Authors: WORRALL G. A.
Published: July 2006

The topographic, climate, geological, and vegetational setting of khartoum is briefly described. The field characterstics of the mail soil group, the High Level Dark Clays, are given, and the secondary minerals, the curved structures, and the interpenetrating horizons are described in some detail and their origins discussed. It is suggested that some features may be fossil.

Laboratory analyses show that the distribution of moisture, soluble salts, and sodium in the profile is uniform, with maxima in the second or third foot. Values in the top 6 in. are always low. The salts consist mainly of sulphate and chloride in the subsoil and of bicarbonate near the surface.The soil is strongly alkaline and consistently verylow in organic nitrogen in all horizons.

The coarsest fractions of the soil consist chiefly of secondary minerals with some quartz, but as the fractions become finer, quartz grains become increasingly abundant. The chemical and minerals composition of the calcareous concretions is given, and they are shown to have formed by replacement. The habit and crystallography of the fibrous and lens gypsum is described and its mode of formation discussed. Microscopic examination of the minerals of the fine fraction showed that, as the content of the light minerals consisted almost entirely of quartz and that the percentage of heavy minerals in the total fine sand averages only 4.3 percent., considerable weathring of the primary minerals must have occurred. From the species and proportions of the heavy minerals present, it is suggested that much of the material may have come from Sudan sources, and that colluviation may have played a large part in its formation.

The classification of the soil is discussed, and the name ‘Solonized Sub‐tropical Black Earth’ proposed.
NITROGEN STUDIES ON THE IRRIGATED SOILS OF THE SUDAN GEZIRA
Authors: JONES T. A.
Published: July 2006

The seasonal variation in the organic‐ and nitrate‐nitrogen content of Gezira soil under irrigated rotational cropping has been studied over six successive years. Accent so far has been placed on the cotton phase of the rotations and statistical analysis of the results has shown that the organic‐nitrogen content of the soil is not increased by rotational cropping beyond an equilibrium value which is presumably a function of the environmental conditions.

Increase of organic nitrogen in Gezira soil appears to be a function of seasonal conditions. Loss of organic nitrogen in marked excess of what could conceivably be explained by crop uptake is a definite feature. The loss occurs gradually throughout the whole season, giving a minimum organic‐nitrogen content in the soil during the hot dry period of February to May.

Accumulation of nitrate‐nitrogen, on the other hand, is dependent on the nature of the rotation and the period of the year. Nitrate accumulates at the beginning of the rainy season when it is rapidly leached to lower soil depths; it also accumulates on the bare fallows during the hot dry season. This latter finding is in accord with the statements of other workers.
A MINERALOGICAL STUDY OF WEATHERING AND SOIL FORMATION FROM OLIVINE BASALT IN NORTHERN IRELAND
Authors: SMITH J.
Published: July 2006

The composition of a soil profile derived from olivine basalt in Northern Ireland is described with the assistance of a series of diagrams of the cumulative curve type incorporating mineralogical and particle size data. The weathering sequence of primary minerals in the basalt is olivine, labradorite, augite. Olivine alters to vermiculite and labradorite to kaolin. The soil resisted all attempts to achieve complete dispersion and its high state of aggregation is considered to affect its physical properties. The presence of quartz is attributed to glacial contamination.
CHEMICAL STUDIES OF PODZOLIC ILLUVIAL HORIZONS
Authors: MARTIN A. E. , REEVE R.
Published: July 2006

A study of the effects of concentration of aqueous acetylacetone, extraction time, and of pH on the extraction of organic carbon and sesquioxides from four widely distributed podzol B horizons is reported. Reaction time has little influence on carbon extraction, but increasing reagent concentration causes, in general, an increase in carbon dispersion. Amounts of ether‐extractable Fe and A1 (removed as complexes of acetylacetone) increase directly with both concentration of reagent and time of contact. 0.2 M acetylacetone at pH 7 removes more carbon and in some cases more Al complex than at pH 4–2, but less Fe is extracted at the higher pH value. Pyrophosphate is more efficient than acetylacetone at the same concentration and pH, and tends to extract more Al and carbon, but less Fe. Sedimentation experiments suggest that the proportions of Al, Fe, and SiO2 remaining in some organic‐matter suspensions are physically distinct from the carbon fractions. An indurated iron‐humus pan from New Zealand yelded very small amounts of ether‐extractable Fe, suggesting that Al may play a predominant role in stabilizing the organic matter in this soil. Some of the extraction data given for the other soils suggest that A1 is likely to act in this way and it is suggested that the function of A1 in podzolization, previously assigned a secondary role, has possibly been overlooked.
THE EFFECT OF NITROGEN ADDITIONS ON FERTILIZER‐PHOSPHORUS AVAILABILITY. II1
Authors: RENNIE D. A. , SOPER R. J.
Published: July 2006

A field and greenhouse study has been made of the effect of nitrogen on the utilization of fertilizer phosphorus by cereal grains. A marked increase in utilization when nitrogen was mixed with either NH4H2PO4 or Ca(H2PO4)2 was shown to occur only when the nitrogen was in the ammonium form. Nitrate sources of nitrogen were relatively ineffective. Placement of nitrogen was important as increased uptake only occurred when the ammonium ion was intimately associated with the phosphorus fertilizer. This stimulative effect of the ammonium ion on phosphorus uptake occurred at a very early stage of crop growth.

Rapid ammonium‐ion absorption by young cereal seedlings occurred irrespective of whether the ammonium source of nitrogen was mixed with, or separated from, the phosphorus carrier. Thus the ammonium ion appears to be the dominant factor; it indirectly influences the plant's ability to take up phosphorus, rather than altering in any way the availability of the applied phosphorus fertilizer.
THE APPLICATION OF SOIL MICROMORPHOLOGY TO FOSSIL SOILS AND OTHER DEPOSITS FROM ARCHAEOLOGICAL SITES
Authors: DALRYMPLE J. B.
Published: July 2006

In 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

The 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

Wet 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

Seasonal 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

The 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

The 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

Drainage 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

The 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

Evidence 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

Data 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

A 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

The 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

An 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

Different 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

The 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

The 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

Bands 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

The 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

Remnants 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

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

The 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

Median 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

Thin 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

The 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

Experiments 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

It 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

The 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

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

image

is applicable to waterlogged soils.
THE AVAILABLE‐WATER CAPACITY OF A SANDY LOAM SOIL
Authors: SALTER P. J. , HAWORTH F.
Published: July 2006

To 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

Two 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

A 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

Hardpan 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

Three 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

A 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

The 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

It 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

Water‐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.