bluuebunny/crossref_metadata_2025_split huggingface dataset:
CHEMICAL STUDIES ON PODZOLIC ILLUVIAL HORIZONS
Authors: MARTIN A. E. , REEVE R. 
Published: July 2006

SummaryIn qualitative studies with a number of soils, organic reagents such as aqueous acetylacetone or cupferron were found to extract a large fraction of the organic matter from podzolic B horizons; smaller quantities were removed from two humic‐gley A horizons. All other soil types tested yielded negligible amounts of carbon with this treatment. Substitution of Cu for the exchangeable cations of a typical Australian black earth followed by treatment with acetylacetone did not result in an increase in organic matter extracted over the untreated soil. It is concluded that, to be extracted by solutions of organic chelate compounds, soil organic matter must be immobilized by ions of one of the transition metals, and the H form must be readily dispersed; it is also possible that large amounts of clay may inhibit extraction. This type of organic matter probably occurs only in the podzolic group of soils.A comparison of the extractive properties of several reagents on two Queens‐ land ground‐water podzols is presented. Cupferron is the most efficient, but complete removal of excess reagent from the final suspension is difficult. Acetylacetone (in water) and oxine (in 50 per cent. acetone) extract a large fraction of the total organic carbon and most of the Al, but the presence of acetone partially inhibits the extraction of carbon. Aqueous oxine is unsatisfactory owing to the extreme dilution of the saturated solution. It is concluded that acetylacetone is the most useful reagent so far tested owing to its miscibility with water and formation of stable ether‐soluble complexes with Fe and Al. Attempts to fractionate the B‐ horizon humus, using salicylaldehyde, acetylacetone and oxine which form progressively more stable complexes with Fe and Al, were unsuccessful owing to the dispersing effect of the NaOH added to adjust the pH values of each reagent. It is suggested that factors controlling the flocculat on of organic colloids from soil suspensions are equally as important as the bonding energy of the metal‐organic matter bonds in determining the extent of dispersion.
MAJOR GENETIC SOILS OF THE ARCTIC SLOPE OF ALASKA1
Authors: TEDROW J. C. F. , DREW J. V. , HILL D. E. , DOUGLAS L. A. 
Published: July 2006

SummaryThe genetic soils of Arctic Alaska can be arranged in a drainage catena. The mature soils on well‐drained sites are Arctic Brown and related soils. The Tundra profile is an imperfectly‐ to poorly‐drained catenamember. The Bogs, with permafrost, occupy many of the broad, flat, very wet areas. No evidence of a qualitative soil‐forming process unique to the Arctic areas is found. Instead, the Arctic Tundra is primarily a northern extension of the hydromorphic soils of the forested regions, whereas the Arctic Brown arid related soils represent the northern extensions of the podzolic process. The term Tundra, when used in connexion with zonal great soil groups along with Podzols, Chernozems, Laterites and related soils, is an erroneous one and its use, except for a hydromorphic soil, should be discouraged. The podzolic process on the stable, well‐drained sites weakens northward, resulting in the successive development of Podzols, Minimal Podzols, Arctic Browns, Arctic Browns shallow phase, and, finally, no soil formation.
STUDIES ON THE BASALTIC SOILS OF NORTHERN IRELAND
Authors: McALEESE D. M. , McCONAGHY S. 
Published: July 2006

SummaryResults are given of the exchangeable calcium, magnesium, sodium, and potassium contents of the sand, silt, and clay fractions separated by purely physicaI methods from sixteen horizons, mainly subsoils from basaltic soil profiles in Northern Ireland. Relatively high exchangeable‐calcium values are recorded, ranging from 6.9 to 20.9 m.e. per cent. for sands, from g to 28 m.e. per cent. for ‘silts, and from 8.3 to 35 m.e. per cent. for clay separates.Exchangeable‐magnesium values are also high, particularly for separates from subsoils with imperfect drainage, and values as high as 17.2, 27.3, and 32–2 m.e. per cent. are recorded for sand, silt, and clay separates, respectively. The exchangeable‐magnesium contents usually increase with depth in the subsoil and in many cases the exchangeable‐magnesium values for silts are as high as or higher than values for corresponding clay separates. Comparisons of the values for sands, ‘ilts’ and for corresponding clays suggest that the high values exhibited by the silts (and often by the sands) cannot be attributed, to any considerable extent, to incomplete dispersion, e.g. to the presence of normally dispersible clay aggregates in the silts or sand separates. It is suggested that these high values and the associated high cation‐exchange capacities of these silts (and coarser fractions) may be due to the presence of partially weathered rock minerals which may be broken down, e.g. by acid treatments and dispersion procedures prior to detailed examinations.
IDENTIFICATION OF CLAY MINERALS FROM ACID SOILS
Authors: TAMURA TSUNEO 
Published: July 2006

SummaryA technique is described for the identification of clay minerals, the layers of which are difficult to expand or collapse by the usual treatment with glycerol and KCl. Samples are extracted for 3 to 6 hours in normal sodium citrate at pH 7–3 and 100° C. The citrate is renewed hourly. After the citrate extraction the inter‐ layer spaces of some minerals can be expanded with glycerol and CaCl2Basal spacings of minerals previously identified as ‘dioctahedral vermiculite’ expand to 16–18 A. after this treatment; hence, their identity is questioned.The widespread occurrence in the north‐eastem United States of clay minerals with 14‐A. spacing necessitates this extraction for correct identification.
THE GILGAIED AND BAD‐STRUCTURED SOILS OF CENTRAL IRAQ
Authors: HARRIS S. A. 
Published: July 2006

SummaryThe variable soils of the recent alluvium of parts of Iraq contain horizons falling into two groups, viz. bad‐structured horizons which are hard and dense with marked vertical cracking, and well‐structured horizons characterized by a friable consistency and higher porosity. Gilgai occurs as the extreme bad‐structured phase. The only constant difference in laboratory data between these groups is the low laboratory permeability in the bad‐structured horizons. These features cannot be explained using the causes so far put forward for gilgaied soils in Australia, but they suggest an explanation of the process of formation of bad structure (in the agricultural sense) in terms of compaction by weathering agents. It is suggested as being a process which is habitually taking part in the development of solonetz soils, since the latter always seem to be characterized by this bad structure.
A SEQUENCE OF BEECHWOOD SOILS ON THE CHILTERN HILLS, ENGLAND
Authors: AVERY B. W. 
Published: July 2006

SummaryThe chalk and associated superficial deposits of the Chiltern Hills give rise under beechwoods to a sequence of soils ranging from rendzina through brown earth (sol lessivé) to podzol, closely paralleled in developmental sequences established elsewhere on uniform calcareous materials. The salient features of the genetic soil types represented are described and their evolution discussed in relation to vegetation and site characteristics. On base‐deficient soils, mor formation under beech is conditioned by local climatic factors and management practices as well as by inherent fertility variations and is only associated with advanced podzolization on appreciably sandy materials. On silty plateau soils with imperfect drainage, ‘micro‐podzols’, which may be transitory, are formed.
THE GEOCHEMISTRY OF BASALTIC MATERIALS AND AUSTRALIA ASSOCIATED SOILS OF SOUTH‐EASTERN SOUTH AUSTRALIA
Authors: TILLER K. G. 
Published: July 2006

SummaryFour profiles in the Mt. Burr forest area of south‐eastern South Australia have been examined in detail. Two profiles were podzolized deep aeolian sands overlying buried soils which had developed on basaltic tuff, a third profile was developed on olivine basalt while the fourth was a composite profile developed on basaltic tuff and containing a buried profile formed on an earlier ash shower.The main factors operative in influencing the geochemical distribution of the elements in these profiles were the translocation of elements by plant growth and their relative mobility on weathering, association with the clay fraction, and restricted drainage. In the aeolian sands Ca, Mn, and V with lesser amounts of K, P, Mo, Cu, Mg, Zr, and Al, were the elements which generally accumulated in the surface horizon as the result of plant action. In the surface soils of volcanic origin Ca, Mn, P, and Mg with lesser amounts of Cu and K accumulated. The highest concentrations in the clay fraction were, in general, for the aeolian sands Al, Fe, Ga, V, and Ni, and in the basaltic soils Na, Al, Ga with, to a lesser extent, K, V, P, and Ni. In the soils developed on basaltic material the elements most readily lost from the weathering zones during soil formation were in decreasing order of magnitude, Ca, P > Na, Mg, Co, Zn > Cu, Mn > Ni. K, V, Ga, Mo, Fe, Al, Ti, and Zr were in general much less mobile and tended t remain incorporated in the weathering products and concentrated in the upper weathering zones. P, Zn, and Cu and to a lesser extent Mn, Fe, Ni, Co, and Ca were found to be more readily lost on weathering under conditions of restricted drainage.The elements most concentrated in the hardpan of a ground‐water podzol were, in decreasing order of magnitude, Fe > Al ≫ V, Zn, Ni > P, K, Mo > Na, Mn, Cu, and Ti. When the more strongly cemented nodules were separated for analysis it was found that relative to the matrix Fe > Al, V, and P, in that order, were most concentrated. Zn alone was lower in the nodules than the sandy matrix. Mn and Mo were most concentrated in the upper part of the hardpan, and Zn, V, Ni, Cu, Ti, and P in the lower part.Some of the mineralogical changes which have taken place during the weathering of the basaltic material have been studied by examination of sand and clay fractions of the soil and thin rock sections. In the olivine basalt, the plagioclase and, to a lesser extent, olivine have weathered most readily. The main weathering products of the soil developed on the olivine basalt were kaolin and haematite. In the tuff the first important weathering product was montmorillonite, formed by the breakdown of the volcanic glass. This montmorillonite was found to break down in the upper weathering zones of the soils formed on tuff to give kaolin and goethite.
CHANGES IN THE SOIL OF A LONG‐CONTINZIED FIELD EXPERIMENT AT SAXMUNDHAM, SUFFOLK
Authors: COOKE G. W. , MATTINGLY G. E. G. , WILLIAMS R. J. B. 
Published: July 2006

SummaryA four‐course rotation experiment was carried out on wheat, mangolds, barley, and legumes. Yields of all crops were much increased by phosphate fertilizers, nitrogen fertilizers increased yields of non‐legumes, extra yields from potash fertilizers were smaller. Fifty‐six years of continuous manuring caused the following changes in the calcareous boulder clay soil: Plots receiving farmyard manure contained half as much again organic carbon as plots receiving fertilizers, plots receiving N and P fertilizers contained slightly more organic matter than plots without these fertilizers. Total soil nitrogen was considerably increased by farmyard manure and was slightly higher on plots receiving sodium nitrate than on plots without nitrogen fertilizer. Total soil phosphorus was built up by farmyard manure and by bone meal, and to a smaller extent by light annual dressings of superphosphate. ‘Soluble phosphorus’ determined by three methods differentiated clearly between plots which had received phosphate fertilirs and those which had received none. An accumulation of bone meal residues was demonstrated by dilute hydrochloric‐acid extraction, but not by methods involving extraction with 0.5 M sodium bicarbonate or equilibrium with 0.01 M calcium chloride. Soluble‐phosphorus values by all three methods indicated the presence of fertilizer residues more clearly than did values for total soil phosphorus. The soil contained a large quantity of total potassium and the values were not materially affected by manuring. Dilute‐HCl‐soluble‐K and exchangeable‐K values differentiated between plots which had received potash fertilizers and those which had received none. They also reflected changes in soluble potassium caused by the different amounts of potassium removed in the crops grown.
THE BUTANA GRASS PATTERNS
Authors: WORRALL G. A. 
Published: July 2006

SummaryA study has been made of the features associated with repeating bands of vegetation in the Butana region of the Sudan. Aerial observations show that they have similar features to those described by MacFadyen in British Somaliland except that the curved bands lie on the interfluves and are convex downslope.The patterns consist entirely of grasses and herbs, and lie on very gentle slopes of about I in zoo; there is no measurable difference in elevation between the grasses and bare areas. Slopes of less than I in 500 have no patterns. The width of the bands is variable, but commonly between 8 and 12 m., and the bare ground about twice the width of the grass.The profile consists of a grey‐brown clay loam, with an A horizon slightly lighter in colour and texture. No difference in profile, composition, or properties between the soil under grass and under bare ground has been detected, except in pH, nitrate, and moisture. There are differences in soil surface, the bare areas being smooth and the grassed areas broken by cracks and potholes which form at the beginning of the rains and concentrate just upslope of the previous season's grass. Experiments to simulate on the bare ground the moisture and growth conditions obtaining under the grass bands were partially successful.The current season's grass concentrates at, and in advance of, the previous season's front, and there is an annual migration of the grass bands upslope. The vegetation consists dominantly of the grasses Aristida spp., Schoenfeldtia gracilis, Cymbopogon nervatus, and Sehima ischaemoides. Species of grass may have a restricted position in the grass band, the most striking being Schoenfeldtia. Herbs are more ephemeral, but are prominent during the rains in the old grass areas.The origin of the patterns appears to be related to water supply, topography, and soil, but not to wind. Comparison with gilgai is made, but reasons are given for considering that the patterns have a different mode of origin, and an initiation due to a type of soil slip or to a rhythmic deposition of vegetation is considered possible.
WATER‐TABLE HEIGHTS IN A DRAINED HOMOGENEOUS SOIL OVERLYING AN INFINITELY PERMEABLE LAYER
Authors: YOUNGS E. G. 
Published: July 2006

SummaryDrainage investigations in the past have been mostly Concerned with soils which are infinitely deep or which overlie impermeable beds, and little attention has been paid to soils which overlie a more permeable layer. Electric‐analogue experiments are described which give solutions to the particular case of a homogeneous soil, drained by a uniform system of ideal drain tubes and overlying an infinitely permeable layer, for different ratios of rainfall intensity to hydraulic conductivity and for various depths of the permeable layer below the drain level. The results are presented in terms of a correction factor which, when multiplied by the height of the water table above the drain level midway between the drain lines which would be observed if the topsoil extended to infinite depth with the same ratio of rainfall to hydraulic conductivity, gives the maximum water‐table height for a given depth of boundary between the soil and permeable layer below the drain level, expressed as a fraction of the half‐spacing of the drains. The correction factor varies with the ratio of rainfall intensity to hydraulic conductivity and the depth of the permeable layer below the drain, approaching unity as this depth increases beyond one‐third of the half‐spacing of the drains. The correction factor obtained here is compared with that obtained for the case of the soil overlying an impermeable bed for the values of the ratio of rainfall intensity to hydraulic conductivity of 0.1, 0.02, 0.05, and 0.10. The two sets of results represent the extreme cases of water‐table heights which can be observed in a two‐layered soil with the drain laid in the top layer.
THE USE OF CHELATING REAGENTS AND ALKALINE SOLUTIONS IN SOIL ORGANIC‐MATTER EXTRACTION
Authors: EVANS L. T. 
Published: July 2006

SummaryThe extent of organic‐matter extraction tended to rise with the pH of the extractant solution, as did the proportion of the humic‐acid fraction in the extracts. Chelating reagents extracted more organic matter than other extractants of comparable pH, but extraction by all reagents rose with increasing time and temperature of extraction. The equivalent weights of both the humic and fulvic fractions of alkaline extracts rose with the temperature of extraction, as did the extent of conversion of the humic‐acid fraction to acid‐soluble compounds. The humic‐acid fraction was flocculated by various salts to a much greater extent than the fulvic fraction. The nature of soil organic‐matter extraction is considered in the light of these results.
THE ORIGIN AND DEVELOPMENT OF BROWN EARTHS ON CLAY‐WITH‐FLINTS AND COOMBE DEPOSITS
Authors: AVERY B. W. , STEPHEN I. , BROWN G. , YAALON D. H. 
Published: July 2006

SummaryField investigation of the origin and development of three brown‐earth (sol Zessiwk) profiles has been supplemented by mechanical and mineralogical analyses and micromorphological studies. Two profiles, representative of the Batcombe and Winchester series, were on Clay‐with‐flints and the third, of the Charity series, on a Coombe deposit.Particle‐size distribution and petrographic data strongly suggest that all three soils are derived in part from loess. The Charity is interpreted as an autoch‐ thonous profile formed in a Head deposit composed of chalky and flinty detritus mixed with loess by soliflwion, whereas the Batcombe and Winchester are two‐ stage profiles, formed in composite (non‐uniform) parent materials resulting from the superficial incorporation of loess with the truncated or redeposited remains of previously weathered horizons with rotlehm and/or braunlehm fabrics. These Clay‐with‐flint substrata contain materials derived from Chalk and Eocene beds in varying proportions, weathered in Tertiary or interglacial periods and rearranged by periglacial agencies. Clay‐with‐flints sensu stricto, as represented in the Win‐ chester subsoil, has distinctive physical, mineralogical, and micromorphological characteristics, and appears to have originated by sub‐surface solution of the Chalk and illuvial accumulation of clay derived for the most part from overlying deposits.The land surfaces concerned have probably been subjected to at least one alternation of periglacial and temperate conditions after the addition of loess. Hence the extent to which either profile reflects the influence of the contemporary environment is not readily assessed, but evidence is adduced that the upper horizons of each profile bear the impress of similar pedogenic processes, including eluviation of clay‐size material and acidic weathering leading to the accumulation of vermiculite, modified in the Winchester by the effects of erosion and soil creep.
A MODIFIED PERMEABILITY TEST FOR MEASURING THE COHESION OF SOIL CRUMBS
Authors: DETTMANN MARGARET G. , EMERSON W. W. 
Published: July 2006

SummaryThe technique previously described (Emerson, J. Soil Sci., 6, 160, 1955) has been improved. A I‐cm. thickness of soil crumbs of standard size (1–2 mm. diameter) is supported on a 1‐cm, layer of glass spheres (0·5–1 mm. diameter), and the permeability measured by percolation of 0·05 N NaCl‐the so‐called ‘initial’ test. Then 3 litres of the same solution are percolated in 24 hours, after which the permeability measurement is repeated—the ‘final’ test. The ratio, K2/K1, of final and initial permeabilities of the crumbs is regarded as a measure of soil cohesion.The technique has been applied to a wide range of soils, on some of which other structural tests had already been made. The results, in four tables, show: (a) a continuous arable system produces very bad structure; (b) a short‐term ley produces an improvement‐as does wheat‐and some of the improvement is detectable after a subsequent year in arable cultivation; (c) attainment of maximum stability is very slow, for 100 years in grass may not be enough; (d) farmyard‐manure residues increased crumb stability on a clay soil, but not on a sand;(e) a ley, and lucerne too, produces a greater increase than root crops.Limitations of the test are: (a) It should not be used unless the soil acidity is approximately the same for all samples. Very acid clay (pH 4 to 5), known to possess a very poor structure, gives a value of K2/K1 close to unity. (b) It may not be safe to compare soils of differing clay content. A poorly structured sandy loam (12 per cent. clay) gives a much higher value of K2/Kl than a clay loam (31 per cent. clay) that field experience would assess as having the better structure.
STUDIES ON THE ORGANIC MATERIAL EXTRACTED FROM SOILS AND COMPOSTS
Authors: GOULDEN J. D. S. , JENKINSON DAVID S. 
Published: July 2006

SummaryThe infra‐red absorption spectra of the ligno‐proteins described in Part I of this series of papers were examined and absorption bands characteristic of the peptide link identified.A reference sample of lignin was prepared from wheat straw and was found to be relatively unchanged by boiling with 2 N sodium hydroxide for 4 hours in the absence of air.The infra‐red spectra of the residues from acid and alkaline hydrolysis of the ligno‐proteins were found to be very similar to that of straw lignin.
THE SOILS OF MAZANDERAN IN NORTHERN IRAN AND THEIR SUITABILITY FOR PADDY‐RICE IRRIGATION
Authors: ANDRIESSE J. P. 
Published: July 2006

SummaryThe soils which occur along the southern shore of the Caspian Sea, in the Mazanderan Province, which is one of the main rice‐producing regions in Iran, are formed mainly from young alluvial deposits in which pedo‐climate is considered to be the major soil‐forming factor.According to differences in pedo‐climate, the soils have been differentiated into soil associations which are related to the topographical situation in which they occur, namely the several landscapes characteristic of the morphology of a we11‐developed riverine plain.The occurrence of salty soils can be explained by the influence of the Caspian in the past, and their reclamation, although theoretically possible by drainage improvement, the application of soil amendments, and adequate leaching, has been found to be very difficult in practice. Soil analyses have shown interrelationships between natural vegetation or crop yield and salty conditions.The soils have been further classified according to their suitability for paddy‐rice cultivation, particularly with regard to the economy of irrigation water.As none of the irrigability classifications yet devised appears to be suitable for the purpose of classifying rice soils, a special system has been developed to meet the circumstances prevailing in Mazanderan.