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Inhibitory Effects of Crop Residue‐Derived Organic Ligands on Phosphate Adsorption Kinetics
Author(s) -
Ohno Tsutomu,
Erich M. Susan
Publication year - 1997
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1997.00472425002600030041x
Subject(s) - adsorption , chemistry , reaction rate constant , phosphate , kinetics , organic matter , phosphorus , residue (chemistry) , nuclear chemistry , organic chemistry , physics , quantum mechanics
This study was conducted to investigate the effects of dissolved organic matter isolated from field corn ( Zea mays L.) and wheat ( Triticum aestivium L.) residue on the kinetics of phosphorus (P) adsorption of an acidic soil. Phosphorus adsorption studies were conducted with the following experimental variables: P concentrations from 10 to 70 µ M , pH from 4.51 to 5.38 and surface area of soil from 13.3 to 39.8 m 2 L −1 . Initial rate of reaction was determined through polynomial fitting of solution [P] at 0, 2, 4, 6, 8, and 10 rain after soil addition. Double‐logarithmic plots were used to obtain reaction orders of 0.64 ± 0.05 for [P], −0.07 ± 0.04 for −log [H], and 1.04 ± 0.17 for surface area. Thus, the experimental rate equation was written as: d [P]/ dt = k f s [P] 0.64 , where [P] is the P concentration in solution, k f is the forward rate constant in L m −2 s −1 units, and s is surface area in m 2 L −1 . The rate constant, k f , was (1.61 ± 0.16) × 10 −6 L m −2 s −1 . The rate constant declined linearly and Al release into solution increased linearly with increasing concentration of dissolved organic matter in solution. This suggests that P adsorption is occurring through reaction with soil Al. Reaction rates determined at 8.8, 15.5, 20.0, 26.0, and 33.5°C demonstrated that Al release from the soil was surface controlled, while P adsorption was under diffusion control. The results of this study suggests that management systems that return crop residues back into the soil may increase the availability of P by decreasing the adsorption of P onto soil surfaces.