摘要:

SummaryPhoto‐induced Electron Spin Resonance signals have been detected in basic aqueous solutions of humic acids from soil and from synthetic and commercial sources. Parameters of these signals under atmospheres of air, O2and N2were the same as or very similar to those of the already known ‘dark’ stable ESR‐signals of humic acids and melanins. The maximum increase of signal amplitude under the influence of 395–780 nm wavelength irradiation was one order of magnitude. The influence of microwave power on ESR‐signal amplitude was examined under different atmospheres. It has been found that oxygen strongly diminishes the saturability of signals. This indicates that oxygen has an influence upon relaxation properties of paramagnetic centres of humic acid. Photoinduced ESR signal is a newly discovered feature of humic acids, similar to that of melanin and may be expected to affect physico‐chemical processes occur

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1975.tb01934.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryMonomeric silica solutions were mixed with solutions containing AlCl3, or Al(OH)2‐55Cl0‐45to give a SiO2/Al2O3, ratio varying from 8 to 8.0 and were kept at pH 6–0, 7.0, or 8.0 over a period of about I year. All precipitates which formed from solutions with SiO2/Al2O3ratios of 1–0 or higher were X‐ray amorphous. The SiO2/Al2O2, ratio of the precipitate varied in the range from 1.0 to 3.0. It increased with the Si concentration and the SiO2/Al2O3ratio of the parent solution and with reaction time. The pH did not affect the SiO2/Al2O3ratio of the precipitate but did affect its dispersion and flocculation. Al3+and Al(OH)2.55+0.45reacted differently with silica and yielded different reaction products. These differences were interpreted in terms of the stability of hydroxy‐Al polymer units in the reaction. The amount of NaOH per Al atom which was required to reach and maintain the same pH, increased with the increasing SiO2/A12O ratio of the precipitate, but the value was generally lower than that predicted from ‘one in four’ substitution of Si by Al in four‐fold co‐ordination. A ‘neutralization’ of the positive charge on the hydroxy‐Al cations by silica was pointed out also to be a cause of the extra acidity. Implications of these observations on synthetic amorphous aluminosilicates to the genesis, structure, and properties of their natural co

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1975.tb01935.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryA rapid, simple, and precise density fractionation of soil mineral‐organic complexes, suitable for routine work, is described. Special features of the method are: low sample weight, use of glass‐fibre paper to collect the lighter fractions, and use of a modified Walkley‐Black procedure to determine the carbon content of the light fraction in test tubes. Density‐distribution curves of organo‐mineral soil complexes are shown to yield useful basic information on degradation processes of soil organic matter caused by cultivation. The results suggest that complexes between clay and organic matter tend to build up preferentially with a certain proportion between the c

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1975.tb01936.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryCorrection factors for neutron moisture meter measurements near the soil surface have been established from readings at several depths taken before and after the removal of 10 cm of surface soil. In determining the factors it is assumed initially that a uniform soil moisture profile exists. The factors are then applied to the measurements and, from calibration of the neutron meter, the soil moisture profile is established. If large variations with depth are revealed, the initial assumption of uniformity of moisture profile does not apply. A method of determining corrections to the computed factors to allow for the variations in the soil moisture with depth is described. This requires a knowledge of the variation of the correction factors with moisture content and methods of determining this are discussed.

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1975.tb01937.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryFive line transects were sited over grass‐covered, convex‐concave slopes in the Berkshire and Wiltshire chalk downs, with the object of describing and interpreting the variation in selected surface soil properties. Previous work had concentrated upon the correlation between single variables and slope gradient and slope length, whereas the emphasis of the present paper lies in examining the interrelationships amongst the variables through the use of principal components analysis.A consistent pattern of variation was established between the five sites. The first component derived from the analysis was interpreted as a combined organic matter and soluble constituents factor, which accounted for between 50 and 60 per cent of the total variance. The second component was identified as particle‐size variation and accounted for a further 13 to 18 per cent of the total variance.Whereas the distribution of the component scores for the second component supported the original idea of a sharp junction effect in the pattern of soil properties on the slope, the first and most important component indicated a more diffuse transition from net erosion to net deposition condi

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1975.tb01938.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryThe total length of soil boundary on a map can be measured by counting the number of intercepts between boundaries and a randomly distributed array of sampling lines. It is thus also possible to estimate the length of the same boundariesbeforesurvey by means of a similar array of field traverses. The per cent sampling error of estimates of boundary density (boundary per unit area), is approximately the reciprocal of the square root of the number of intercepts.

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1975.tb01939.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryComputer methods currently used at Aberystwyth for handling the many observations of soil and site during survey are described. While complex statistical analysis of the data is possible, the emphasis in this paper is on automatic sorting according to existing classifications and land–use, assessing the contents of map–units, and producing automatic dot distribution maps from grid data.Changes in class limits are easily made to give alternative maps. This is illustrated by land–use capability maps of Pembrokeshire.A feedback technique allows identification of sites like those growing particular crops or crop combinations, so that maps of potential crop land are produced. Provisional maps of potential barley and early potato land in Pembrokeshire illustrate the technique. Questions of computing strategy and the relevance of economic conditions are disc

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1975.tb01940.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryHydrolysis, defined as double decomposition between Na‐adsorbent and water, occurred to extremely limited extent in suspensions of Na or Na‐Ca smectites, soil, or Dowex‐50. High pH, near 10 or above, occurred only when CaCO3was present. Concentrations of Na were from 1–5 me/l in systems containing CaCO3, With Na or Na‐Ca Dowex‐5o and CaCO3, in CO2‐free water or NaCl solution, pH and concentrations of Na in solution‐phase were predictable from Na‐Ca exchange coefficients, CaCO3, solubility product, and ionization c

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1975.tb01941.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SummaryIn almost all soil surveys some attempt is made in the early stages to assess the scale on which the soil changes, and the information required is often obtained from transects. By recording soil properties at a constant close spacing on such transects methods of analysis, especially those devised for time series, data can be applied to reveal patterns of variation, and hence lead to rational mapping strategy. Correlograms, which show on average the relation of soil at one point to that at another, seem especially promising.The potential of time series analysis in soil survey was explored by measuring soil properties in three horizons in profiles at 10 m intervals along a transect across the Lower Jurassic outcrop in north Oxfordshire. Correlograms were computed for clay, silt, pH, CaCO3, colour value, and stoniness in each horizon. They showed that, for all the properties, the relation between sampling points weakened steadily over distances from 10 m to about 230 m. The average spacing between geological boundaries on the transect was also about 230 m, and outcrop lithology was inferred as one of the main sources of soil variation. The effect of rock type was eliminated by computing deviations of the original values from the means of the outcrops in which they occurred. Correlograms of these showed almost no relation between points more than 10 m apart; i.e. the only other major source of variation occurred within 10 m.In this instance mappable soil boundaries are likely to occur on average every 230 m, and sampling at a spacing closer than I15 m would be needed to detect them from profile inspection alone. Alternatively a map of the geological boundaries with descriptions of the soil for each map unit would constitute almost the best soil map that could be achieved in this area.

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1975.tb01942.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY