THE DETERMINATION OF IONIC DIFFUSION COEFFICIENTS IN FIELD SOILS. I. DIFFUSION COEFFICIENTS IN SIEVED SOILS IN RELATION TO WATER CONTENT AND BULK DENSITY

Summary A method for measuring diffusion coefficients in large cores of structured field soils has been developed and tested, in the first instance using sieved soil. Bromide-chloride and bromide-nitrate counter diffusion coefficients have been determined using ion exchange membranes as sinks for the diffusing ions. The effects of membrane selectivity, soil surface preparation, solution concentration, water content and bulk density have been investigated. The organic colloid content appears to have a considerable influence on the impedance factor-water content relationship of a soil. Increasing the bulk density at constant volumetric water content linearly reduced the impedance factor by up to 30 per cent. The relationship between impedance factor and bulk density is discussed.

[1]  W. D. Kemper,et al.  Movement of Nutrients to Plant Roots , 1968 .

[2]  P. F. Low.  EFFECT OF QUASI‐CRYSTALLINE WATER ON RATE PROCESSES INVOLVED IN PLANT NUTRITION , 1962 .

[3]  P. Nye,et al.  THE MEASUREMENT AND MECHANISM OF ION DIFFUSION IN SOILS III. THE EFFECT OF MOISTURE CONTENT AND SOIL‐SOLUTION CONCENTRATION ON THE SELF‐DIFFUSION OF IONS IN SOILS , 1967 .

[4]  S. A. Barber,et al.  Diffusion of Zinc in Soil: I. The Influence of Soil Moisture1 , 1972 .

[5]  I. Graham-Bryce.  SELF-DIFFUSION OF IONS IN SOIL: I. CATIONS , 1963 .

[6]  W. D. Kemper,et al.  Chloride diffusion in soils as influenced by moisture content. , 1960 .

[7]  W. D. Kemper,et al.  Mobility of Water Adjacent to Mineral Surfaces 1 , 1964 .

[8]  W. D. Kemper.  Water and Ion Movement in Thin Films as Influenced by the Electrostatic Charge and Diffuse Layer of Cations Associated With Clay Mineral Surfaces , 1960 .

[9]  M. Drew,et al.  THE MEASUREMENT AND MECHANISM OF ION DIFFUSION IN SOILS.: IV. THE CONCENTRATION DEPENDENCE OF DIFFUSION COEFFICIENTS OF POTASSIUM IN SOILS AT A RANGE OF MOISTURE LEVELS AND A METHOD FOR THE ESTIMATION OF THE DIFFERENTIAL DIFFUSION COEFFICIENT AT ANY CONCENTRATION , 1968 .

[10]  P. Nye,et al.  THE MEASUREMENT AND MECHANISM OF ION DIFFUSION IN SOILS: II. AN EXCHANGE RESIN PAPER METHOD FOR MEASUREMENT OF THE DIFFUSIVE FLUX AND DIFFUSION COEFFICIENT OF NUTRIENT IONS IN SOILS , 1966 .

[11]  Peter J. Gregory,et al.  Nutrient relations of winter wheat: 2. Movement of nutrients to the root and their uptake , 1979, The Journal of Agricultural Science.

[12]  P. Tinker.  A STEADY‐STATE METHOD FOR DETERMINING DIFFUSION COEFFICIENTS IN SOIL , 1969 .

[13]  I. Graham-Bryce.  SELF‐DIFFUSION OF IONS IN SOIL , 1963 .