ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1974.tb01135.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryIn comparison with the situation twenty‐five years ago, the analysis of soil‐water hysteresis has been transformed by the concepts of independent and non‐independent domains, and the analysis of the diffusion‐like movement of water in unsaturated soil has led to a theory of the development of water content profiles which was only vestigial at the time of the founding of the British Society of Soil Science. The theory of the control of ground water has greatly developed, mostly along established lines, as also have field methods of determining the hydraulic conductivity necessary for the application of this theory. In striking contrast, the debate about the assessment of soil texture pursues its course un

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1974.tb01136.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryFulvic acid extracted from peat was partially fractionated on anion and cation exchange resins. In the latter case the fractionation is attributed to the presence in fulvic acid of components possessing amine groups; this was confirmed by chemical means and by infrared spectroscopic evidence. The infrared and ultraviolet spectra of fulvic acid and its various fractions are discussed and the occurrence of carboxyl, phenolic, and amine groups in fulvic acid and the fractions obtained is considered. It was further established that nitrous acid can destroy the amine groups present in fulvic acid.

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1974.tb01137.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryEvidence is presented, based on sequestration, chemical behaviour, ultra‐violet and infra‐red spectroscopy, to indicate the formation between the non‐cationic fraction of fulvic acid and a variety of transition metal ions, of stable soluble complexes and also of insoluble complexes over the complete pH range. The soluble complexes formed under alkaline conditions are negatively charged. The fulvic material is very effective in competing with other ligands for the metal ions. Mechanisms for the flocculation of the soil organic matter in the presence of heavy metal ions are discussed. The formation of inert complexes between cobalt and the fulvic material is also demonstrated and its implications to the study of metallo‐organic complexes are di

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1974.tb01138.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryThe amounts of hydroxyl ions released from hydrous alumina during phosphate adsorption were measured at constant pH values and at different phosphate concentrations using an automatic titrator. The hydroxyl ions released were plotted against phosphate adsorbed and the equations that gave best fit to the data were differentiated. The variation in the differentials (dOH/dP) with increasing phosphate adsorption was consistent with the theory, proposed below, on the type of sites responsible for phosphate adsorption, by synthetic hydrous alumina containing bayerite and pseudoboehmite, at different concentrations.At low phosphate adsorption which corresponded to low phosphorus concentration, adsorption took place mainly by displacing aquo groups (Al‐H2O). With increase in phosphorus concentration hydroxo groups (Al‐OH) became the predominant sites of adsorption.At still higher concentrations, where phosphate adsorption displacing aquo and hydroxo groups was nearly completed, the hydroxyl bridges linking aluminium atoms (Al‐OH‐Al, ol groups) were broken. This created new sites which were responsible for additional adsorption of phosphate at these concent

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1974.tb01139.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryVegetation cover is shown to play a major role in determining the soil moisture content in the Front Range of the Rocky Mountains near Calgary. Thus lodge‐pole pine abstracts more moisture from the soil both in summer and winter than aspen, while least moisture loss is experienced on bare soil. Clearly vegetation cover must be kept constant when comparing two soils. Additional important variables are aspect and parent material. It was also found that permanent (IS bar) wilting‐point, as commonly used, bears little relation to the permanent wilting‐point of even the more moisture‐loving native trees studied. They all do not wilt until a much lower moisture content is

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1974.tb01140.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryIodine in each of the forms iodide, elemental iodine, and iodate was added, at a rate of 5 mg/kg to a sandy loam and to mixtures of the soil with composted grass roots, chalk and sesquixoides, and its solubility determined after various periods of incubation.With iodide, solubility in both 0.01 M CaCl2and 1.0 M NK4acetate (pH 4.8) declined rapidly over the period o to 3 days and subsequently reached approximate equilibrium levels of 2.8 per cent solubility in CaCl2and 7.8 per cent in NH4acetate, these values being the means of samples incubated for 48, 103, and 160 days. The partial (5 per cent) replacement of the soil by composted grass roots had no appreciable effect on the solubility of added iodide, while chalk, incorporated at a rate of 5 per cent, depressed the solubility of iodide in CaCl2to 1.8 per cent but caused a slight increase in solubility in NH4acetate. The incorporation of 2 per cent hydrated ferric oxide or of 2 per cent hydrated aluminium oxide reduced the solubility of iodide in CaCl2to 0.1 and 0.3 per cent, and in NH4, acetate to 3.8 and 5.7 per cent respectively. Elemental iodine was similar to iodide in its solubility in the two extractants and in its response to the various soil treatments. Iodate, however, differed considerably from the other two forms of iodine. With soil alone, and with the soil/chalk mixture, its decline in solubility with increasing incubation time was relatively slow, although after 160 days its solubility was similar to that of iodide and elemental iodine. The incorporation of composted grass roots caused a rapid reduction in iodate solubility, suggesting that the organic matter accelerated the reduction of iodate to elemental iodine or iodide. With the treatments involving the incorporation of ferric and aluminium oxides, there appeared to be considerable sorption of iodate during the 16 h extraction period and the effects of these materials on iodate solubility during incubation were therefore difficult to assess.

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1974.tb01141.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryIron chelates of some simple di‐and trihydric phenols can be decomposed by peroxide treatment or by hydrolysis to yield crystalline ferric oxides. The species of ferric oxide obtained depends upon the precipitating conditions and the nature of the chelating ligand. In oxidative virtually anion‐free conditions, decomposition of all aged chelates yields a precipitate of disordered ferric oxide, which is referred to as‘protohaematite’, since it ages to haematite in water even at room temperature. Protohaematite is considered to be a discrete form of ferric oxide similar in structure to δ‐FeOOH but devoid of hydroxyl groups and may be present in freely drained soils as a precursor of haematite. Hydrolysis of all unaged chelates, except that of iron protocatechuic acid, yields lepidocrocite. The redox cycle undergone by iron in this reaction may be analogous to one prevailing in gley soils. In the presence of montmorillonite, the iron‐catechol system forms a clay‐metal‐organic complex, which also decomposes to yield lepidocrocite provided chloride ions are present on the clay surface. The fact that various inorganic gels amorphous to X‐rays can also deplete the ligand content of the chelates indicates a possible inorganic decomposition mechanism for metal‐organ

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1974.tb01142.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryPolysaccharide material was isolated by absorption on charcoal from the acidified, non‐humic fraction extracted by alkali from three soils. The polysaccharides were used as substrates in soil incubation, perfusion, and suspension experiments. Concordant results were obtained with freely drained Countess‐wells and Insch Association soils derived from acidic and basic igneous parent materials respectively. Polysaccharide material added to soil at low concentration (I per cent) was apparently totally decomposed after 8 weeks when the amounts of polysaccharide in control and amended soils were statistically indistinguishable. At higher concentrations (2‐3 per cent) a significant difference in reducing sugar, equivalent to about 30 per cent of the substrate, remained after 32 weeks. Partial neutralization of the polysaccharide material with calcium hydroxide increased the rate of decomposition in Countesswells Association soil but had an opposite, smaller effect in Insch Association soil. Soil polysaccharide material was decomposed slightly faster in perfusion and suspension experiments than in moist soil. Only 20 per cent of the carbohydrate in the unfractionated alkali–soluble organic matter of soil was decomposed during incubation in soil for up to 133 weeks. There was usually little change in the carbohydrate content of soil incubated alone. The soil microbial population showed a marked increase in response to added polysaccharide material but only slight qualitative changes were detected.It is concluded that the persistence of naturally occurring polysaccharide in soil is related to inaccessibility caused by chemical combination, complexing or insolubility but not to a biologically‐stable molecular

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1974.tb01143.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

SummaryThe evaporation of polyethylene glycol zoo from three remoulded clay soils and a clay aerogel was observed by scanning–electron and incident‐light microscopy. Neither flexing of the fabric during recession of the liquid film, nor reorganization of clay domains during shrinkage, was detec

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1974.tb01144.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY