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MEASUREMENT AND MECHANISM OF ION DIFFUSION IN SOIL X. PREDICTION OF SOIL ACIDITY GRADIENTS IN ACID‐BASE TRANSFERS
Author(s) -
NYE P. H.,
RAMZAN M.
Publication year - 1979
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1979.tb00963.x
Subject(s) - chemistry , diffusion , rhizosphere , soil ph , base (topology) , soil water , inorganic chemistry , acid–base reaction , analytical chemistry (journal) , environmental chemistry , soil science , thermodynamics , environmental science , geology , mathematics , paleontology , mathematical analysis , physics , bacteria
Summary The concentration gradient of soil acid neutralised when a block of moist soil was placed in contact with a source of HCO 3 ‐ was predicted from an equation for diffusion of HCO 3 ‐, and its simultaneous reaction with the soil. The reaction was defined by empirical rate constants describing the changes of pH with time in a soil: M/100 CaCl 2 + KHCO 3 solution, suspension system. Values of these constants, determined independently, were too large resulting in prediction of steeper and leas extensive concentration profiles of soil acid neutralised than measured in the diffusion system. The true pH of the soil pore solution in the block would have been considerably greater than a predicted ‘equilibrium’ pH. The consequences for rhizosphere processes are discussed.