Premium
Effect of shape on oxygen diffusion and aerobic respiration in soil aggregates
Author(s) -
Greenwood D. J.,
Goodman D.,
Nelder J. A.
Publication year - 1964
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740151107
Subject(s) - diffusion equation , regular polygon , oxygen , volume (thermodynamics) , chemistry , work (physics) , rate equation , mathematics , geometry , thermodynamics , physics , classical mechanics , economy , service (business) , organic chemistry , economics , kinetics
An equation that related the shape of irregular soil aggregates to their respiration rates and the oxygen concentration at their surfaces was verified experimentally. For this purpose, models of soil aggregates were prepared by cutting shapes from agar containing yeast and glucose. The respiration rates of these shapes when surrounded by different oxygen partial pressures approximately fitted the equation when the shapes had shape factors [surface area/(volume) 2/3 ] of between 5.5 and 6.8. Since sieved soil aggregates had shape factors independent of size and had values of between 5.3 and 6.1 it was concluded that the equation also applied to soil aggregates. To facilitate the foregoing work, a method was developed for determining the surface area‐to‐volume ratios of soil aggregates from measurements of the mean lengths of random chords through the aggregates. It was found that the equation previously used 3 for relating these two parameters held only if the chords were thrown at random in a certain way. A different equation was deduced which applied when the chords were thrown in a slightly different random way. Experimental verification of the two equations was obtained for a range of convex and non‐convex bodies.