bluuebunny/crossref_metadata_2025_split huggingface dataset:
SOLUBILITY OF ALUMINIUM IN SOILS OF THE HUMID TROPICS
Authors: RHODES EDWARD R. , LINDSAY W. L. 
Published: July 2006

SummarySoil samples obtained from genetic horizons of an upland and acid sulphate soil of Sierra Leone, were equilibrated with 0.01 M CaCI using a 1:2 soil to solution ratio. Al3+ activity was estimated from total Al measured in the equilibrium extract, by accounting for hydrolysis and the formation of other complex species.The Al3+ activity was pH‐dependent, but the Al(OH)3 ion product was I'airly constant throughout the upland soil profile; Al3+ activity was near that expected for equilibrium with kaolinite and quartz.In the acid sulphate soil alunite appeared to control the activity of Al3+.
EFFECT OF TEMPERATURE AND SOIL DRYING ON THE TRANSFORMATION OF (14C) GLUCOSE IN SOIL
Authors: CHESHIRE M. V. , SPARLING G. P. , MUNDIE C. M. , SHEPHERD H. , MURAYAMA S. 
Published: July 2006

SummaryTwo different soils, either fresh, or dried and remoistened, were incubated with 1% labelled glucose for 28 days at about 20° or 5 °C and the transformation of the glucose to other sugars measured.Xylose formed a much greater proportion of the sugars synthesized at low temperature in pre‐dried soil than in fresh soil, or at 20 °C in pre‐dried or fresh soil. Numbers of bacteria, fungi (including actinomycetes) and yeasts were determined for each type of incubation. Because the combination of conditions leading to xylose synthesis by yeasts in predried soil are unlikely in the natural state it is concluded that most soil xylose originates in the residues of plants.
EFFECTS OF CULTIVATION ON SOIL WATER RETENTION AND WATER USE BY CEREALS IN CLAY SOILS
Authors: GOSS M. J. , HOWSE K. R. , HARRIS W. 
Published: July 2006

SummaryThe effects are repotted of direct drilling and mouldboard ploughing on soil water retention and extraction in three soils over two to four years.In the years 1972–75 when winter rainfall was close to or greater than the long‐term average the maximum soil water content of the upper 100 cm differed little between the cultivation treatments. In contrast, after the dry winter of 1975–76, about 10 per cent more water was stored in the direct‐drilled soil, especially below 50 cm. In the following dry summer, winter wheat extracted up to 22 mm more water from uncultivated soil and this was associated with better growth of the crop than after ploughing.When simulated rain was applied, water infiltrated rapidly to a depth of 50–100 cm in direct‐drilled soil, whereas on ploughed land its movement was retarded below the plough sole even when cultivation had been carried out under conditions which minimized smearing. Water storage at depth was consequently greater under dry conditions in the direct‐drilled soil while excess water reached drain depth more rapidly in wet conditions.
PHENOLIC HYDROLYSIS PRODUCTS FROM GEL CHROMATOGRAPHIC FRACTIONS OF SOIL HUMIC ACIDS
Authors: TATE K. R. , ANDERSON H. A. 
Published: July 2006

SummaryHumic acids extracted from the Bh horizon of a kauri (Agathis australis) podzol and the A horizon of a yellow‐brown earth under hard beech (Nothofagus truncata), both New Zealand soils, were fractionated by a ‘salt boundary’ technique using a dextran gel, and the fractions hydrolysed with 6 M hydrochloric acid. Lignin‐derived phenolic acids were analysed by gas chromatography of the ether‐soluble hydrolysis products of the humic acids.The lignin derivatives from the kauri podzol humic acid are probably modern products derived from the present‐day scrub vegetation, whereas those from the yellow‐brown earth humic acid are derived from the deciduous vegetation.
THE RATE OF SOIL SURVEY IN BRITAIN
Authors: BECKETT P. H. T. 
Published: July 2006

SummaryTypical rates of soil survey (area, length of boundary and number of observations per day or hour) are presented for routine surveys on 1:25,000 and 1:10,560 base maps by the Soil Surveys of Scotland, and of England and Wales, in five areas.The distance a soil surveyor walks between observations sites each day is highly correlated with (Area surveyed x No. of observation sites).
PORE SPACE VARIABILITY IN A SUB‐SURFACE HORIZON OF TWO SOILS
Authors: MURPHY C. P. , BANFIELD C. F. 
Published: July 2006

SummaryImage analysis was used to investigate the variability of pore space in soil thin sections. Two fine‐textured soil profiles (or pedons) were sampled by inserting eight Kubiena tins (7.5 × 6 × 4 cm) in ledges at 50 cm depth. From each soil block three horizontal thin sections (7.5 × 6 cm) were made and photographed. Each photograph was then divided into nine ‘frames’ so that the voids in each of these frames could be measured using the Quantimet 720 Image Analysing Computer.The results show the variability of three specific pore‐space characters and the consequent need to sample a number of large thin sections from several sample blocks for each soil horizon to obtain estimates of sample means with suitable accuracy.
REACTIONS OF AMMONIA WITH SOIL II. SORPTION OF NH3 ON ENGLISH SOILS AND ON WYOMING BENTONITE
Authors: ASHWORTH J. 
Published: July 2006

SummarySorption isotherms and heats of sorption of NH3 gas on soils, Wyoming bentonite and silica gel were measured at 27 °C after preliminary drying at 22°‐290 °C. Sorption of NMe3 was also measured on some of the materials.Sorption on soils was not very sensitive to change in drying temperature, even though soil water content was markedly affected. Sorption on bentonite was dependent on drying temperature because this affected ease of lamellar separation.The results suggest that under the conditions employed, NH3 sorption on the English soils studied is predominantly due to its protonation at pH‐dependent charge sites and partly to co‐ordination with exchangeable Mg or Ca (but not Na or K). Sorption through mechanisms involving hydrogen bonding is apparently negligible.
REACTIONS OF AMMONIA WITH SOIL, III SORPTION OF AQUEOUS NH3 BY HOMOIONIC SOIL CLAYS
Authors: ASHWORTH J. , PYMAN M. A. F. 
Published: July 2006

SummaryHomoionic clay suspensions were equilibrated at 25°C with aqueous NH, (0.01 to 0.30 M) by agitating for several days. Using clays extracted from three different soils, sorption of NH3, measured by titration, followed the order Na > Ca > NH4 ‐clay. The difference in NH3 sorption between Na‐clay and NH4 ‐clay was matched by an increase in Na + ion concentration in the aqueous phase of suspensions of Na‐clay treated with NH3, but there was no such effect with Ca‐clay.Sorption of NH3 on NH4 ‐clay in aqueous suspension is considered due to proton donation at sites of pH‐dependent charge, and the additional sorption on Na‐clay to displacement of Na + by NH4+ ions. The additional sorption on Ca‐clay seems largely due to co‐ordination of Ca2+ ions with molecular NH. Exchangeable cations affect NH3 sorption differently when an aqueous phase is present than when dried homoionic materials are treated with NH3 gas.
EFFECTS OF solUTION: SOIL RATIO AND VIGOUR OF SHAKING ON THE RATE OF PHOSPHATE ADSORPTION BY SOIL
Authors: BARROW N. J. , SHAW T. C. 
Published: July 2006

SummaryThe effects were measured of varying the solution: soil ratio, and the vigour of shaking on the rate of adsorption of phosphate. One soil appeared to break down with vigorous shaking, prior to adding phosphate, especially at low solution: soil ratio. As a result, subsequent phosphate adsorption was faster. With gentle shaking, there was no effect of solution: soil ratio with the soil. Another soil was more stable and there were only small differences due to vigour of shaking and no effect of solution: soil ratio with any method of shaking.The change in phosphate concentration was not proportional to the reciprocal of time as reported by Ryden and Syers (1975) and Hope and Syers (1976). Hence the validity of extrapolating from short sections of reciprocal‐time graphs in order to estimate equilibrium is questioned.
EFFECTS OF BENOMYL ON IRON AND MANGANESE REDUCTION AND REDOX POTENTIAL IN FLOODED SOIL
Authors: PAL SUDHANSU S. , SUDHAKAR‐BARIK  , SETHUNATHAN N. 
Published: July 2006

SummaryBenlate (50 per cent wettable powder), the commercial formulation of the systemic fungicide benomyl, was applied to a flooded alluvial soil at concentrations of 5 to 100 μg/g active ingredient. At about the field application rate (S μg/g), benomyl retarded the decrease in the redox potentials of the flooded soil and curtailed the accumulation of iron and manganese in solution, both without and with added rice straw (0.5 per cent).
COMPARISON OF MEASURED AND PREDICTED SOIL MOISTURE DEFICITS
Authors: HALL D. G. M. , HEAVEN F. W. 
Published: July 2006

SummaryThe moisture regimes of two fen soils and two chalk soils in Lincolnshire were investigated using a neutron probe moisture meter. Soil moisture deficits were calculated and compared with those predicted using meteorological data. Measured deficits were in fairly close agreement to those predicted by two separate models, the main variation seeming to depend upon the dryness of the year, the crop and the soil type.Measured deficits were also compared with laboratory estimates of available water and it was found that the chalk soils dried to higher suctions than was at first expected.
OXYGEN CONCENTRATIONS IN A CLAY SOIL AFTER PLOUGHING OR DIRECT DRILLING
Authors: DOWDELL R. J. , BURFORD R.CREES.J. R. , CANNELL R. Q. 
Published: July 2006

SummaryThe concentration of oxygen at three depths (15, 30 and 60 cm) has been measured in a direct‐drilled or ploughed clay soil of low hydraulic conductivity (Evesnam series) which was cropped with winter wheat in three consecutive growing seasons (1972/73 to 1974/75). The mean oxygen concentrations between January and March varied with the seasonal rainfall; in the relatively dry winter of 1972/73they were 20 per cent (v/v) at 15 cm and 12 per cent (v/v) at 60 cm, but in the wetter winters of 1973/74 and 1974/75 they were less than 11 and 6 per cent (v/v) at 15 and 60 cms respectively. Direct drilling resulted in higher oxygen concentrations at 15 cm than ploughing in both wetter winters, the mean concentration being 10.2 and 7.2 per cent (v/v) in direct‐drilled and ploughed plots respectively. Frequency distributions of values obtained at individual sampling points showed that when the mean oxygen concentration of the soil at 15 cm decreased to its annual minimum (in January‐March), a significantly higher proportion of the sampling points under direct drilling continued to show concentrations of oxygen greater than 10 per cent (v/v).The results are interpreted as indicating that the higher oxygen concentrations found in this soil after direct drilling are due to the development of a system of continuous large pores and channels which would otherwise be destroyed by annual ploughing.
STRUCTURAL STUDIES ON SOIL POLYSACCHARIDE
Authors: CHESHIRE M. V. , BRACEWELL J. M. , MUNDIE C. M. , ROBERTSON G. W. , RUSSELL J. D. , FRASER A. R. 
Published: July 2006

SummaryThe polysaccharide extracted by alkali from a Countesswells series soil has been fully methylated and the hydrolysis products identified by GC‐MS. The parent neutral sugars are galactose, glucose, mannose, arabinose, xylose, fucose and rhamnose and these constitute about 40 per cent of the polysaccharide. The analysis shows that hexose components are predominantly present in 1 → 3 and 1 → 4 linkages and pentose sugar in 1 → 4 linkages. About 20 per cent of the residues were in branching positions.From the number of non‐reducing terminal groups present the average molecular weight of the methylated material has been calculated to be about 1460 compared with a value of 2700 obtained by vapour pressure osmometry. This contrasts with much higher values reported for unmethylated soil polysaccharides.The mixture of derivatives obtained supports the concept that soil polysaccharide originates in both plants and microorganisms.
SYNTHETIC ALLOPHANE AND IMOGOLITE
Authors: WADA S.‐I. , ETO A. , WADA K. 
Published: July 2006

SummaryIn order to prepare allophane and imogolite in the laboratory, solutions containing l–2× 10–3 M orthosilicic acid and 4–0.5 × 10–3 M A1C13 (SiO2/Al2O3 molar ratio; 0.5, 1.0, 2.0, 4.0 and 8.0) were heated at 95–100°C for 113 hours after addition of NaOH (NaOH/Al molar ratio; 1.0, 2.0, 2.8 and 3.0). Boehmite was found in the precipitates from all solutions with initial SiO2/Al2O3 ratios of 0.5. Imogolite was found with allophane II in the products from solutions with SiO2/Al2O3 ratios of 1.0 or greater and with NaOH/Al ratios of 2.8 or less (final pH 5.0), whereas allophane I was found in the precipitates from solutions with the same SiO2/Al2O3 ratios but with the NaOH/Al ratio of 3.0 (final pH = 5.0–6.3). The mode of formation, chemical composition, infrared spectra, electron micrographs, electron diffraction patterns and differential thermal analysis curves of synthetic imogolite and allophanes (I and II) were compared with those of their natural counterparts.
A CRYSTALLINITY INDEX FOR SOIL KAOLINS AND ITS RELATION TO PARENT ROCK, CLIMATE AND SOIL MATURITY
Authors: HUGHES J. C. , BROWN G. 
Published: July 2006

SummaryTo sub‐divide the large group of kaolinitic soil clays a new empirical index of crystallinity was obtained from the X‐ray diffraction patterns of eight standard kaolins. The index used is the ratio of the intensity above background of the peak at 4.46Å to the intensity above background at about 2.43Å (43.2° 2θ CoKα) and ranges from 4.8 for halloysite to 83 for a well‐ordered triclinic kaolinite. For the kaolins from a group of soils from S.W. Nigeria, the ratio lies between 4.3 and 13.7 and can be tentatively related to the presence of weatherable minerals in the soil and/or the length of the dry season.
EFFECTS OF DIFFERENT METHODS OF CULTIVATION AND DIRECT DRILLING, AND DISPOSAL OF STRAW RESIDUES, ON POPULATIONS OF EARTHWORMS
Authors: BARNES B. T. , ELLIS F. B. 
Published: July 2006

SummaryNumbers of earthworms collected from direct‐drilled or ploughed land were studied during successive years on contrasting soil types sown with cereals.Samples were taken in autumn using a combination of chemical expulsion and hand sorting of soil. The population was consistently larger on direct‐drilled than on ploughed land, and the difference became greater in each successive year. Deep burrowing species were affected similarly to the population as a whole. Population differences on the two treatments were greater with spring — than autumn ‐ sown crops. After tine cultivation numbers were usually similar to those after ploughing.On a direct‐drilled clay soil on which straw had been either burned, or chopped and spread, no differences were recorded in the overall population. However, significantly larger numbers of deep burrowing species were found on the chopped and spread areas, whereas on the burned areas numbers of Allolobophora chlorotica were significantly greater.
SELECTIVE EXTRACTION OF AMORPHOUS IRON OXIDES BY EDTA FROM A DANISH SANDY LOAM
Authors: BORGGAARD O. K. 
Published: July 2006

SummaryEDTA extracts (pH 7.5–10.5) from a Danish sandy loam showed no significant (95% level) increase in amounts of aluminium, calcium, iron, and magnesium between three and nine months' shaking. The amounts were independent of the soil: solution ratio (1:10–1:50), the EDTA concentration (0.01 M–0.2 M), and crushing the soil (< 0.25 mm or < 2 mm). IR spectroscopy and X‐ray diffraction showed no change in the mineral composition of the soil during the extraction. The extracted iron was equal to that extracted after 2 h by ammonium oxalate at pH 3.0. EDTA extraction at pH > 7.5 seems to extract selectively iron oxides with solubility products > ∼ 10−41.
UV AND VISIBLE ABSORPTION SPECTROSCOPIC INVESTIGATIONS IN RELATION TO MACROMOLECULAR CHARACTERISTICS OF HUMIC SUBSTANCES
Authors: GHOSH KUNAL , SCHNITZER M. 
Published: July 2006

SummaryHumic substances were investigated by both UV and visible absorption spectroscopic methods with special emphasis on their macromolecular characteristics. The spectral ranges examined were 200–350 nm and 350–700 nm. Conclusions were drawn on the basis of absorption intensities in optical density (O.D.) vs. wavelength (λ) curves, slopes of log O.D. vs. log λ plots, nature of shoulders in the 250–270 nm region, and E4/E6 ratios. As macromolecular characteristics are expected to be dependent on the medium, studies were carried out at different pH values as well as at different neutral salt concentrations, the two major parameters influencing the soil environment.It was noted that with increasing neutral electrolyte concentrations, the particle size decreased, probably due to the coiling of the macromolecule.On increasing the pH from 6.5 to 9.5, the particle size increased slightly, possibly because of partial association through homolytic bonding. At pH 3.5 (with FA only), the degree of association was greater than that at pH 9.5. However, here association occurred by a different mechanism, that of intermolecular hydrogen bonding. At pH 2.0 (with FA only), association was markedly pronounced because of the very dominant role played by intermolecular hydrogen bonding.
RELATION OF SEVERAL PEDOLOGICAL CHARACTERISTICS TO ENGINEERING QUALITIES OF SOIL
Authors: DE LA ROSA D. 
Published: July 2006

SummaryAn attempt to predict engineering qualities which are needed in soil evaluation and to enhance nonagricultural use of soil survey data was made. Data from a variety of soils were subjected to simple correlation and multiple regression analyses to relate three pedologic characteristics: clay content, cation‐exchange capacity (CEC), and organic matter content to two engineering qualitites: plasticity index, and optimum moisture. Simple correlation coefficients showed that clay content and CEC correlated significantly with the engineering determinations. The relationship between organic matter content and these engineering determinations was weaker. Multiple regression analyses showed that the three pedologic characteristics accounted for most of the variation in each of the engineering qualities, and that prediction was feasible.
THE PLASTIC LIMIT, AS DETERMINED BY THE DROP‐CONE TEST, IN RELATION TO THE MECHANICAL BEHAVIOUR OF SOIL
Authors: CAMPBELL D. J. , STAFFORD J. V. , BLACKWELL P. S. 
Published: July 2006

SummaryThe variation with water content is examined of soil cohesion, soil‐metal friction, susceptibility to soil compaction, implement draught and the slope and intercept of the virgin compression line of critical state soil mechanics theory. For a given soil, all these relations are shown to exhibit turning points at a similar water content which corresponds to the cone penetrometer plastic limit, as determined with a drop‐cone penetrometer, rather than the Casagrande plastic limit. The cone penetrometer plastic limit, which can also be more reliably determined than the Casagrande plastic limit, is the better indicator of soil behaviour in the field and of the water content at which the soil changes from the brittle to the plastic state.
A LYSIMETER STUDY USING NITROGEN‐15 ON THE UPTAKE OF FERTILIZER NITROGEN BY PERENNIAL RYEGRASS SWARDS AND LOSSES BY LEACHING
Authors: DOWDELL R. J. , WEBSTER C. P. 
Published: July 2006

SummaryPerennial ryegrass growing in monolith lysimeters and treated with 400 kg N ha‐1 as calcium nitrate labelled with nitrogen‐15 (10.5 atoms per cent), during one growing season recovered between 43 and 54 per cent of the fertilizer nitrogen. In the following year without further nitrogen additions 4.6–9.5 per cent was taken up, whilst in the fifth year the recovery was less than 1 per cent. The contribution of non‐fertilizer sources of nitrogen to the total nitrogen taken up by the plants during the season that nitrogen was applied was estimated using tracer methods to be about 13–14 g N m‐2 year‐1. The estimate from measuring the nitrogen content of an unfertilized sward was 7 g N m‐2 year‐1. The residual effects of a fertilizer application are likely to be detectable for a period of between 6 and 9 years.Losses of nitrogen to drainage in the winter after application represented 2–5 per cent of the fertilizer applied, whilst in subsequent years the amounts did not exceed 0.1 per cent. Mean concentrations of nitrate ranged between 4 and 16 mg N I‐1. Fertilizer contributed about 60–70 per cent of the total nitrogen lost in the first winter after nitrogen application and 45–60 per cent averaged over three winters.
THE EFFECTS OF GRINDING ON MICROBIAL AND NON‐MICROBIAL ORGANIC MATTER IN SOIL
Authors: POWLSON D. S. 
Published: July 2006

SummaryGrinding more than doubled the respiration rate of two silt loam soils, one arable and one grassland. The increases were smaller when the grinding treatment was given to portions of soils that had previously been fumigated with CHCI3and incubated, a treatment that greatly decreased microbial biomass.The results indicate that the flush of decomposition caused by grinding was in part derived from killed organisms and in part from enhanced decomposition of non‐biomass sections of the soil organic matter. Grinding killed about a quarter of the biomass in both soils. Carbon from killed organisms accounted for a quarter of the extra CO2–C evolved after grinding in the arable soil and almost half in the grassland soil. The extra non‐biomass organic matter decomposing after grinding amounted to about 0.5% of the soil organic carbon in both soils. This non‐biomass material rendered decomposable by grinding had a higher C/N ratio than the organic matter decomposing in unground soil.
CLAY AND SILT MINERALOGY OF SOME SOILS FROM QASIM, SAUDI ARABIA
Authors: MASHHADY A. S. , REDA M. , WILSON M. J. , MACKENZIE R. C. 
Published: July 2006

SummaryQasim, some 500 km north‐west of Riyadh, is one of the agriculturally important areas of Saudi Arabia. Silt fractions of the soils of the Wadi ar Rimah and side wadis, classified as Torrifluvents, are characterized by high quartz contents and the universal occurrence of kaolinite and felspar, generally with plagioclase predominant; mica, chlorite and hornblende also generally occur. The clay fractions contain mainly palygorskite and a smectite‐mica interstratification with smaller amounts of kaolinite, traces of quartz and occasionally chlorite. Palygorskite generally increases in content with depth. Variations in mineralogy probably reflect changes in depositional conditions rather than pedogenic processes; possible reasons for the high palygorskite content are discussed. Sedentary soils (Torriorthents) reflect the mineralogy of the rock from which they were derived. In clay fractions from salt‐marsh soils (Salorthids) calcite reacts strongly with smectite‐mica during DTA.