bluuebunny/crossref_metadata_2025_split huggingface dataset:
The application of some image‐analysis techniques to recognition of soil micromorphological features
Authors: TERRIBILE F. , FITZPATRICK E.A. 
Published: August 2005

SummaryA number of image analysis techniques, largely drawn from remote sensing, have been applied to soil thin sections in an attempt (i) to overcome some of the limitations of previous approaches and (ii) to identify some complex soil features.Using different wavelengths and light polarizations, microscopic images of thin sections obtained from different horizons were digitized. It was then possible to carry out a series of experiments including geometric corrections, creation of multilayer images, principal component transformation, classification procedures, morphological analysis and modelling of bi‐dimensional optical anisotropy of the soil matrix.As a special procedure, principal component images were included in the multilayer images, thereby improving the classification on which a morphological analysis was conducted. The reliability of the procedure was tested against point counting and was found to be successful. The overall procedure allowed the combination of brightness and shape classifications. Bi‐dimensional matrix optical anisotropy was detected at 256 levels and plotted as a three‐dimensional perspective view, thus creating a new way of studying this feature.
Adsorption of selenite to goethite in a flow‐through reaction chamber
Authors: GLASAUER S. , DONER H.E. , GEHRING A.U. 
Published: August 2005

SummaryAdsorption of selenite on goethites in NaCl and Na2SO4 solutions was performed in a newly designed flow‐through reaction chamber as well as in a traditional batch system. Six goethites with different morphologies were used as adsorbents. For the experiments the goethite was placed in the chamber prior to flushing with the salts. Introduction of the NaCl and Na2SO4 solutions only, and in combination with selenite, resulted in different responses with respect to the pH. The pH changes were explained by means of anion‐binding energies, with Cl− <SC42− <SeO32−. Neither the morphological characteristics of the adsorbents nor the electrolyte anion influenced the amount and the rate of selenite adsorption, The mixing mode in the reactor chamber affected the selenite adsorption density, as indicated by higher densities in the batch experiments.
Evaluation of two coal‐derived organic products in ameliorating surface and subsurface soil acidity
Authors: NOBLE A. D. , RANDALL P. J. , JAMES T. R. 
Published: August 2005

SummaryAcidity in the soil surface and subsurface is of major concern in horticulture, cropping and pasture production systems in southern Australia. Broadcast applications of lime to the surface have proved to be ineffective in ameliorating subsurface acidity in the short term. Two calcium‐saturated coal‐derived organic products, an ‘oxi‐product’ (OXPR) and an ‘oxi‐fulvate’ (OXFU), were evaluated for use as liming materials with specific consideration given to amelioration of subsurface acidity. The effects of these two organic products and of lime on the chemical composition of the A1 and A2 horizons of an acid red podzol were investigated in leaching columns, 20 cm long. OXPR and OXFU supplying 80 or 160 g Ca m−2 were compared to 160 g Ca m−2 applied as CaCO3 and a control receiving no amendments. The effects of CaCO3 on exchangeable Al and pH were limited to the surface 2 cm. In contrast, the two organic amendments were effective in decreasing exchangeable Al and increasing pH and exchangeable Ca to depth, the extent being a function of amendment and rate applied. The formation of inorganic and organic complexes were assumed to be responsible for the movement of Al out of the column in the leachate, although significant quantities of Al were precipitated in the column. Significant linear regressions were observed between the ionic strength and Al in the leachate. Significant quantities of Mg and K were displaced by Ca and leached from the column; consequently, this loss must be considered against the benefits of decreased exchangeable Al when assessing fertility for plant production.
Proton and copper binding by humic acid: application of a discrete‐site/electrostatic ion‐binding model
Authors: TIPPING E. , FITCH A. , STEVENSON F. J. 
Published: August 2005

SummaryA discrete‐site/electrostatic model of ion binding by humic substances has been applied to proton‐and copper‐binding data for a soil humic acid. The proton data cover the pH range 3–9 and the ionic strength range 0.001 m‐0.1 m, while those for copper refer to the pH range 4–5, ionic strengths between 0.005 m and 0.1 m, and p[Cu] values between 3 and 8. The model is able to explain the major observed trends, including the dependence of proton and copper binding on ionic strength and the binding of copper as a function of pH. However, the calculated ionic strength dependence of copper binding is slightly less than that observed. In addition, the model has been used to predict ratios of protons released to copper bound under different conditions, on the basis of the separately estimated parameters for proton and copper binding. The model correctly predicts the ratios to be between 1 and 2, and to decrease with increasing bound copper and with pH.
Iron(III) reduction by natural humic acids: a potentiometric and spectroscopic study
Authors: DEIANA S. , GESSA C. , MANUNZA B. , RAUSA R. , SOLINAS V. 
Published: August 2005

SummaryThe reduction of iron(III) by natural humic acid (NHA) was studied in aqueous solution as a function of pH, time and iron(III) concentration. The information gained from FTIR and ESR spectroscopies as well as potentiometric data suggests that redox reactions occur at a low pH due to the involvement of phenolic groups and radicals. At pH values higher than 3.5 the reaction is strongly inhibited by the formation of iron(III)–humate complexes.
Entropy and sustainability
Authors: ADDISCOTT T.M. 
Published: August 2005

SummarySoil–plant systems exchange both energy and matter with their surroundings and are consequently open systems thermodynamically. They should therefore tend towards a steady state described by non‐equilibrium thermodynamics and characterized by minimum production of entropy. The theory surrounding the principle of minimum entropy production provides a good analogue of the behaviour of natural and agricultural ecosystems subjected to perturbations. Entropy‐increasing processes are those that degrade complex, ordered structures of large molecular weight to small molecules such as CO2, NH3 and H2O. Processes such as photosynthesis that build small molecules into larger ones lessen entropy. These ordering processes are permitted by thermodynamic work performed when heat is transferred from the sun. They depend critically on the capacity of the system for self‐organization, which is identified with its biological potential. Several of the small molecules are environmentally undesirable in excess. This, together with the theoretical considerations above, suggests that minimum production of entropy should be a criterion of sustainability. It implies that agricultural systems should be allowed to become steady states where possible and that maintaining the biological potential is essential. An ‘audit of small molecules’ is suggested as a way of assessing sustainability.
Effects of addition of clay minerals on the fatty acid fraction of a podzol soil
Authors: JAMBU P. , AMBLÈS A. , MAGNOUX P. , PARLANTI E. 
Published: August 2005

SummaryThe Al horizon of a sandy podzol soil, with a very small proportion of clay‐sized material, was sampled and homogenized. Samples, both with and without supplementation with 150 g clay minerals kg−1, natural heteroionic bentonite (saturated with Na, Ca, Mg, K), Mg‐bentonite or Fe‐kaolinite, were moistened to two‐thirds of water‐holding capacity and incubated at 28°C for 16 weeks.After incubation, lipids were extracted with 3:1 light petroleum: ethylacetate mixture in a Soxhlet apparatus as unbound components (directly extractable by organic solvents) and bound components (only extractable after treatment with acids). Monoacids (free and esterified), diacids, ketoacids and hydroxyacids were isolated from the two lipidic fractions (unbound and bound) by column chromatography. The different components of each family were analyzed by gas chromatography (GC) or gas chromatography‐mass spectrometry (GC‐MS).Incubation without supplementation generated a selective decrease in abundance of free mono‐acids in unbound and bound fractions. The decrease was in inverse proportion to the chain‐length of components. Soil supplementation with bentonite (homoionic or heteroionic) did not induce an overall quantitative change, but promoted a transfer of fatty acids from the unbound to the bound fraction, increased the exchange between free and esterified monoacids (transesterification) and stimulated hydrolysis of glycerides. In contrast, soil supplementation with Fe‐kaolinite caused much decomposition or biotransformation of monoacids but it did not induce change either in the intensity of transesterification in the wax ester fraction or in the intensity of hydrolysis in the glyceride fraction.
Use and accuracy of the filter‐paper technique for measurement of soil matric potential
Authors: DEKA R.N. , WAIRIU M. , MTAKWA P.W. , MULLINS C.E. , VEENENDAAL E.M. , TOWNEND J. 
Published: August 2005

SummaryA filter–paper technique that can be used to measure the matric potential of field soil is described in detail. When a calibrated batch of filter papers is used, the precision is limited by the variability between individual papers and the limitation of weighing to the nearest mg. The absolute accuracy is also limited by the instruments used for calibration. There was reasonable agreement between batches of the same type of paper, suggesting that our generalized calibration curves can be used for Whatman No. 42 filter papers where accuracy is not paramount.For potentials ≥−2.5 MPa, papers need to be equilibrated with the soil for 6 d. To achieve the same accuracy at lower potentials longer equilibration periods are required. Results suggest that the technique should be effective down to at least −100 MPa if soils are allowed to equilibrate fully with the papers. Coefficients of determination (r2) for the calibration lines were all ≥0.92. A regression of log(‐matric potential) measured by the filter paper technique against measurements made using tensiometers and a psychrometer over a range of potentials between −1 kPa and −10 MPa gave an r2 value of 0.995.
Field‐based partition coefficients for trace elements in soil solutions
Authors: GOODDY D.C. , SHAND P. , KINNIBURGH D.G. , VAN RIEMSDIJK W.H. 
Published: August 2005

SummaryA total of 48 elements was detected in the soil solutions centrifuged from two acid sandy (humus‐iron podzol) profiles from southern England. Concentrations ranged from mm for the major ions to mm for trace metals such as U and the rare earth elements. Field‐based solid/solution partition coefficients, Kd, were determined by calculating the ratio of the amount of an element extracted by 0.43 m HNO3 or a neutral salt (0.01 m CaCl2 or 0.1 m Ba(NO3)2) to the concentration in the soil solution. These partition coefficients did not show the expected trend in selectivity. For example, Cd consistently had one of the highest Kd values, higher even than Cu. This was thought to be due in part to the nature of the Kd which reflects a balance between binding to the soil solids and to the dissolved organic carbon (DOC), which is present at relatively high concentrations (1–20 mm) in the soil solutions. Because of the underlying functional similarity between metal binding by the solid and dissolved organic matter, the partition coefficient (and hence element mobility) will be relatively insensitive to changes in pH and metal‐ion activity in the soil solution.
Sorptive interactions of pesticides in soils treated with modified humic acids
Authors: ALMENDROS G. 
Published: August 2005

SummaryDifferent structural changes in peat humic acid (HA) were induced through treatments leading to chemical derivatization and/or the removal of functional groups. Eleven humic products were obtained after acetylation, amidation, ammonia fixation, methylation, nitration, oximation, sulphonation, selective degradations and ‘fixation’ of stearic acid. The sorption of 12 pesticides (alachlor, atrazine, carbofuran, 2,4‐D, 2,4‐DB, methyl parathion, metoxuron, monouron, prometryne, propanil, fenoprop and chloranil) on the above products was determined by ultraviolet derivatographic spectroscopy. In addition, pesticide sorption was evaluated on samples from neutral and calcic soils treated with the corresponding potassium humates. The most intense interactions occurred in samples from the neutral plot, whereas the greatest effect of the humic matter in enhancing pesticide sorption was found with the calcic soil. As expected, the sorption patterns in HA‐pesticide systems were poorly correlated with those in soil‐HA‐pesticide systems. In the former case, the sorption performance was influenced mainly by hydrophobic interactions, whereas in the latter it depended on the participation of multiple parameters suggesting that the molecular volume and the van der Waals energy of the pesticide molecule play a chief role. The HA characteristics most frequently correlated with pesticide sorption were those connected with the aromatic/aliphatic ratio and the particle size. In the calcic‐soil‐HA‐pesticide systems, the base saturation of the exchange complex correlated negatively with pesticide sorption.
Applications of the continuous‐flow stirred‐cell (CFSC) technique: II. The adsorption behaviour of Na, Cs, Sr, Cu, Ni and Pb on humic acids
Authors: RANDLE K. , HARTMANN E.H. 
Published: August 2005

SummaryThe first part of this paper deals with the sorption of Na, Cs, Sr, Ni, Cu and Pb on two humic fractions derived from a soil. The sorption data for individual elements were obtained using the continuous‐flow stirred‐cell (CFSC) technique, in which the metal sorptive solution is pumped through a cell containing a known mass of the humic acid retained by a filter and the solution emerging from the cell was analysed by either atomic absorption spectrometry (Cu, Ni and Pb) or by the combined use of radioisotope dilution and gamma‐ray spectroscopy (Na, Cs and Sr). Sorption isotherms were determined at two flow rates. It was found that, in general, the sorption isotherms for all the metals studied could be described by the Langmuir equation and parameters derived from the fitted line provided information on the metal‐humate binding strengths and the maximum amount of metal sorbed per unit mass of humic acid. Caesium showed anomalous behaviour at certain flow rates in both its sorption and desorption behaviour.In the second part of the paper we discuss the sequential sorption and desorption of one metal by another on the same humic fraction, using Na, Cs, Zn and Cd. The aim was to elucidate the nature of the binding process when several metals were competing simultaneously for the functional groups on the humic acids. In addition, at the end of the experiment, the humic material was isolated and analysed by gamma‐ray spectroscopy to determine the metals still bound in this fraction. Some tentative conclusions concerning the nature of the metal‐humate complexes are made on the basis of these data.
Zinc sorption by acid tropical soils as affected by cultivation
Authors: GUADALIX M.E. , PARDO M.T. 
Published: August 2005

SummaryThe sorption of zinc (Zn) by two acid tropical soils, Mazowe clay loam (kaolinitic, coarse, Rhodic Kandiustalf) and Bulawayo clay loam (coarse, kaolinitic, Lithic Rodustalf), was studied over a wide range of Zn solution concentrations. Samples of the two soils used in the experiments were collected at both uncleared, uncultivated (virgin) sites and cultivated sites. The two virgin soils showed similar abilities to bind Zn. Mazowe soil (40 g organic matter kg−1) presented the highest affinity for Zn. Yet, Bulawayo soil (23.5 g organic matter kg−1) sorbed almost the same amount. Bulawayo soil had higher pH and Fe and Mn‐oxide content than Mazowe soil. Once cultivated, the two soils behaved quite differently. After 50 years, Mazowe soil had lost 60% of its organic matter and effective cation exchange capacity (ECEC). In this soil, Zn sorption capacity had also been decreased by 60%. Clearing and 10 years under cultivation had affected neither the organic matter content nor the ECEC of Bulawayo soil. For this soil, Zn sorption was even higher in the cultivated soil, presumably due to an increase in the amount of Fe and Mn oxide from subsoiling. Zinc sorption was dependent upon pH, with retention dramatically increasing in the pH range 6–7. Sorption occurred at pH values below the point of zero charge (PZC), indicating that the sorption reaction can proceed even in the presence of electrostatic repulsion between the positively charged soil surface and the cation. In the two soils, the reversibility of the sorption reaction was very low. More than 90% of the sorbed Zn was apparently strongly bonded.
Water retention models for fractal soil structures
Authors: BIRD N.R.A. , BARTOLI F. , DEXTER A.R. 
Published: August 2005

SummaryA review of water retention functions based upon fractal soil structures is presented. We consider the modelling approach for a fractal fabric, a fractal pore boundary and a fractal pore space, identifying the latter case as one of particular complexity. In each case, the water retention function is derived from the pore volume distribution arising from the structural model in question. We examine published models and highlight problems, namely lack of generality and inconsistency with the assumed fractal structure. The models considered in this paper do not account for the effects of pore connectivity, and as such their validity as a necessary condition for the existence of fractal structure is questionable.
Spectroscopic control of iron oxide dissolution in two ferralitic soils
Authors: MALENGREAU N. , BEDIDI A. , MULLER J.‐P. , HERBILLON A.J. 
Published: August 2005

SummarySecond derivative diffuse reflectance spectroscopy (DRS) in the visible range has been used to characterize changes in colour and identify the nature of Fe oxides which withstand reduction during experimental yellowing of reddish materials. It is accepted that haematite dissolves preferentially and faster than goethite, and Al‐substitution controls the dissolution kinetics of Fe oxides. However, DRS has shown that haematite is more resistant than predicted and that some Fe‐oxides, probably trapped within kaolinite particles, are inaccessible to solvents. DRS allows the nature of dissolved phases at each deferration step to be determined and changes in Al‐content of residual phases throughout deferration to be followed. It also demonstrated that Helmholtz coordinates correlate very well with changes in Fe‐oxide mineralogy and are preferable to redness ratings when monitoring differential dissolution of Fe oxides through colour measurements. DRS is a powerful and sensitive technique for monitoring the dissolution of Fe oxides in soils.
Organic matter composition in sewage farm soils: Investigations by 13C‐NMR and pyrolysis‐field ionization mass spectrometry
Authors: LEINWEBER P. , BLUMENSTEIN O. , SCHULTEN H.‐R. 
Published: August 2005

SummaryThe composition of soil organic matter (SOM) on sewage farms south of Berlin was investigated by solid‐state CP/MAS 13C‐NMR and pyrolysis‐field ionization mass spectrometry (Py‐FIMS) of freeze‐dried sewage solids and soil samples of differing contamination. These were an untreated soil (USOIL), a former sewage farm used as arable land since 1990 (SF90A), and a recent sewage farm (SF1994). The CP/MAS 13C‐NMR spectra showed enrichments of the sewage‐treated soils with aliphatic C and C in OCH3‐groups and amino acids. In the Py‐FI mass spectra the major markers of sewage and SOM in sewage farm soils were (i) N‐containing compounds, in particular peptides, (ii) dimethylphthalate (m/z 194), (iii) sterols, and (iv) signals in the mass range m/z 502 to 554 of mono‐ and diaryl esters which were substituted by long aliphatic chains. The latter signals were intense in the sewage solids, increased in intensity from sample SF90A to SF1994; but they were not present in the USOIL, thus clearly indicating anthropogenic origin. Temperature‐resolved Py‐FIMS showed that the SOM compounds in the sewage farm soils were generally incorporated into bonds with widely different stabilities which could be relevant for SOM turnover and environmental effects. This is demonstrated for the trapping of dimethylphthalate in a modelled humic substance.
Total carbon and nitrogen in the soils of the world
Authors: BATJES N.H. 
Published: August 2005

SummaryThe soil is important in sequestering atmospheric CO2 and in emitting trace gases (e.g. CO2, CH4 and N2O) that are radiatively active and enhance the ‘greenhouse’ effect. Land use changes and predicted global warming, through their effects on net primary productivity, the plant community and soil conditions, may have important effects on the size of the organic matter pool in the soil and directly affect the atmospheric concentration of these trace gases.A discrepancy of approximately 350 × 1015 g (or Pg) of C in two recent estimates of soil carbon reserves worldwide is evaluated using the geo‐referenced database developed for the World Inventory of Soil Emission Potentials (WISE) project. This database holds 4353 soil profiles distributed globally which are considered to represent the soil units shown on a 1/2° latitude by 1/2° longitude version of the corrected and digitized 1:5 M FAO–UNESCO Soil Map of the World.Total soil carbon pools for the entire land area of the world, excluding carbon held in the litter layer and charcoal, amounts to 2157–2293 Pg of C in the upper 100 cm. Soil organic carbon is estimated to be 684–724 Pg of C in the upper 30 cm, 1462–1548 Pg of C in the upper 100 cm, and 2376–2456 Pg of C in the upper 200 cm. Although deforestation, changes in land use and predicted climate change can alter the amount of organic carbon held in the superficial soil layers rapidly, this is less so for the soil carbonate carbon. An estimated 695–748 Pg of carbonate‐C is held in the upper 100 cm of the world's soils. Mean C: N ratios of soil organic matter range from 9.9 for arid Yermosols to 25.8 for Histosols. Global amounts of soil nitrogen are estimated to be 133–140 Pg of N for the upper 100 cm. Possible changes in soil organic carbon and nitrogen dynamics caused by increased concentrations of atmospheric CO2 and the predicted associated rise in temperature are discussed.
Analysis of the green fraction of humic acids
Authors: WATANABE A. , FUJIMORI H. , NAGAI Y. , MIYAJIMA T. , KUWATSUKA S. 
Published: August 2005

SummaryThe green fraction of humic acids (HAs), Pg, was fractionated by gel chromatography on Sephadex G‐50. Repeated chromatography of the crude Pg obtained by the first chromatography of HA yielded a sharp peak (G1) and two broad bands (G2) of purified Pg. The recovery of Pg in G1 and G2 as percentages of the total Pg content of the HA were 16.2 and 14.5%, respectively. Distinct peaks were detected at 615, 570, 450 and 280 nm in the UV‐visible spectra of both G1 and G2 in alkali solutions. Estimates of weight‐average molecular weight were 9.7 * 103 for G1 and 1.23 * 104 for G2. In the 1H‐NMR spectra the percentage of hydroxyl groups of 4,9‐dihydroxy‐perylene‐3, 10‐quinone (DHPQ) nuclei, which are known to be the chromophore of Pg, was 4.1 and 4.5% of the total H, respectively. Based on these values and the H/C ratios, DHPQ‐C was estimated as 28% of total C. 13C‐NMR spectra obtained using inverse‐gated decoupling yielded 40–41% aromatic C, which suggested the presence of aromatic rings other than DHPQ. All of the IR, 13C‐ and 1H‐NMR spectra indicated that the two purified Pg samples largely differed from each other in their contents of alkyl and polysaccharide components.