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Mathematical models to study the kinetics of potassium release from swell‐shrink soils of Central India in relation to their mineralogy
Author(s) -
Rao Ch. Srinivasa,
Pal D. K.,
Takkar P. N.
Publication year - 1998
Publication title -
zeitschrift für pflanzenernährung und bodenkunde
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 0044-3263
DOI - 10.1002/jpln.1998.3581610111
Subject(s) - soil water , silt , chemistry , diffusion , potassium , mineralogy , soil science , analytical chemistry (journal) , geology , environmental chemistry , thermodynamics , physics , paleontology , organic chemistry
Employing four mathematical models (first‐order, parabolic‐diffusion, Elovich and zero‐order), kinetics of potassium desorption from eight soils with and without cropping were studied to evaluate their ability in explaining K release from soils. The decline in the soil test K in cropped soils over original soils was drastic in easily desorbable forms compared to that of strongly held forms like 3 M H 2 SO 4 K. Results showed that parabolic diffusion as well as first‐order kinetic equation explained the K release data well for both original and K depleted (cropped) soils. Elovich and zero‐order equations were not suitable to describe the kinetic data. However, zero‐order equation explained K release data better in case of K‐depleted soils as compared to original soils. Soils with higher initial K contents registered higher release rate constants. Over the entire period of cropping the range of release rate (b) decreased from 1.26 to 1.53 × 10 −2 to values ranging from 1.12 to 1.30 × 10 −2 h −1 . In contrast, the first‐order equation, parabolic diffusion showed higher b values for cropped soils as they represent the diffusion gradient. Mica and its biotite content in both silt and clay fractions showed significant correlation (r) with b values. Similarly with the rate of K release, clay content of soils maintained significant r whereas the silt content did not.