摘要:

SummaryAn equation has been derived for the relation between permeability and the size distribution of the pores in isotropic material. If the mean radius of the pores in each of n equal fractions of the total pore space is represented in decreasing order of size by r1, r2., and rn cm. respectively, then permeability is given bywhere is the porosity in cm.3/cm.2of porous material, and K is in units of cm.2By this means, permeability can be calculated from she curve relating water content to suction. This has been tested on published data for flow of air through porous stones and flow of water through saturated and unsaturated sands. Calculated values have been found to agree satisfactorily with measured values over a wide range of permeability.The Kozeny equation is discussed as a particular case of this equation

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1958.tb01892.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SummaryThere are two possible ways of ordering natural formations: (1) by simplification in order to save time and to make possible an easy grouping by forgoing detailed specification (ordering by one or by a limited number of definite properties); (2) by forgoing simplification and by giving full weight to detailed specification in the establishment of the systematic units, in order to make possible the application of the system in every branch of general and applied science that deals in some way or other with the natural formation to be defined and ordered (ordering by differential diagnosis with no restriction to number or kind of properties).Both the above systems of ordering are possible with soils. Both are justified, their respective application depending on aims, purposes, and necessities. They could neither fight nor help each other; they are divided from the very beginning by their different principles and goals which lead necessarily to two independent branches of soil systematics.

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1958.tb01893.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SummaryNo mature soils were observed in the area round Kerman, much of which was occupied by lithosols and regosols. The profiles of immature soils on the fine outwash alluvium occupying some of the broad valleys suggested that the zonal Great Soil Group would be a Reddish Desert Soil. Phosphate and potassium levels of cultivated soils on the fine alluvium are adequate or good; the total nitrogen content is low, though higher on cultivated than on uncultivated soils.

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1958.tb01894.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

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

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1958.tb01895.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SummaryEight krasnozem (red‐earth) profiles representing a wide range of environments have been studied. Contrasting features of the soils can be explained by differences in parent material, climate, vegetation, and land use. The main effects corresponding to these variations are seen in the relative contents of total and readily soluble aluminium, organic carbon, nitrogen, organic phosphorus, and of exchangeable metal cations.Land utilization appears to have led to losses in organic carbon, nitrogen, organic phosphorus, exchangeable cations, and ‘available’ manganese. These losses suggest the possibility of a potassium deficiency and are in agreement with observed nitrogen deficiencies.The cation‐exchange capacity of the organic matter is much greater than that of the inorganic matter, and in some soils extrapolation suggests that losses of organic matter threaten the capacity of the soils to retain

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1958.tb01896.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SummaryChemical data are presented for a number of related topsoil, subsoil, and termite‐soil samples collected in mulched coffee established on a laterized red loam coffee soil.The comparisons of mean values for soil organic carbon, total base‐exchange capacity, total exchangeable bases, exchangeable calcium, and exchangeable magnesium show that there is no statistically significant mean difference between the topsoil and termite‐soil sample results. The subsoil sample results, however, are significantly lower than either the topsoil or termite‐soil samples in all these results.Similar comparisons of the mean values for soil pH and exchangeable calcium plus magnesium, when expressed as a percentage of the total exchangeable bases, show that the soil has been altered byOdontotermes badius(Hav.) in constructing the ‘runs; it is left with a higher pH value and with an increased proportion of the total exchangeable bases present as calcium plus magnesium.It is not possible from these results to say conclusively whether the termite soil samples are derived from the adjacent topsoil or subsoil.It is concluded that the presence of the termite soil which eventually becomes intimately mixed with the topsoil during cultivation and weed‐control operations is not a point to be considered againstOdontotermes badius(Hav.) when assessing the ‘pros and cons’ of its presence in

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1958.tb01897.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

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 deta

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1958.tb01898.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SummaryThe clay separates (<2μ) isolated from the horizons of ten basaltic soil profiles are shown by X‐ray analysis to have a mixedmineralogical composition; the type and amount of each mineral present being dependent on the drainage conditions within the profile.Kaolin, the end product of weathering, generally predominates in surface horizons. Vermiculite is formed in well‐drained profiles, but where gleying symptoms are evident vermiculite is replaced by montmorillonite, the amount of which increases with increased degree of waterlogging. Illite occurs in only two profiles to any appreciable extent.It is inferred that soil separates other than clay are contributing to the cationexchange capacity of these s

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1958.tb01899.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SummaryX‐ray and chemical studies of silt separates (2–20μ) from basaltic soils were made to determine the origin of the rather high cation‐exchange capacities (C.E.C.) found for these separates. The silts as isolated by the usual method of mechanical analysis consisted in the main of quartz and feldspars with variable amounts of clay minerals which occurred as aggregates. These aggregates were of two types:(a) Composed of clay‐size particles, i.e.<2μ cemented or bound into silt‐size aggregates by ‘free’ sesquioxides of which the basaltic soils have a high content. The aggregates were disrupted by reduction and the clay particles subsequently released.(b) ‘Pseudo‐aggregates’ which were shown to be individual particles of silt‐size dimensions and having a flaky appearance. These particles were either vermiculitic (under good drainage conditions) or montmorillonitic (under poor drainage conditions), and it is suggested that they form intermediate products in the weathering of primary‐rock minerals to clay minerals.Whilst the major contributor to the C.E.C. of the silts was undoubtedly the ‘pseudo‐aggregates’ and to a lesser extent the true clay aggregates, most of the silt separates had a much higher C.E.C. than implied by

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1958.tb01900.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SummaryTitration curves of humus suspensions (prepared from some representative podzol B horizons by acetylacetone extraction) in o.1 N KCL are Presented. The shape of each curve (in absence of added metal ions) and the apparent PKvalue (PKe) derived from it are affected by the amount of Al contained in the suspension. One soil extract (initial PH 3.6) had a C/Al ratio of 4.9 and gave PKe= 6.21, Whereas the amberlite‐treated extract (initial PH 2.6) had a C/Al ratio of 152 and PKe= 4.12. Extrapolation of PKevalues to zero concentration of Al gave limiting values of 4.o and 3.8 for the humus extracted from a Queensland and a New Zealand podzol respectively. These figures are lower than those normally quoted for humic acid, but they may be characteristic of the translocated humus of podzols.Titration curves of fresh humus extracts with added Al+++, Fe+++or divalent transition metal ions did not suggest the presence of complex sites although the results for Fe+++are uncertain owing to the complexity of the equilibria involved Similar titrations with added Al+++and Cu++using amberlite‐treated extracts did not indicate potential complex sites and, as before, the Fe+++data were inconclusive. By analogy with Cu++it is unlikely that Fe complexes ate present in these systems. It is concluded that humus is immobilized in these horizons by elexctrostatic bonding with Al+++(since free Fe+++would not exist at the soil PH), and the residual Al contained in the organic micelles in suspension is probably also bound by Coulomb forces. It is pointed out that the approximate methods used in this study for practically metal‐free preparations may not reveal the presence of the type of complexes found by other workers for some synthetic Polyelectro

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1958.tb01901.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY