Sorption of Nonionic Organic Compounds by Corn Residues from a No‐Tillage Field

Abstract

AbstractThe sorptive uptake of three representative nonionic organic compounds (NOCs) from water by corn (Zea mays L.) residues and surface soil from a no‐tillage field was evaluated. Sorption isotherms of benzene, ethylbenzene, and 1,2,3‐trichlorobenzene by the corn residues and soils were linear, and the degree of uptake was inversely related to the water solubility of the NOC. Sorption coefficients of the corn residues were from 35 to 60 times greater than for the surface soil (1.9% organic matter), demonstrating the high sorptive capabilities of these residues. The sorptive characteristics of isolated plant cuticle were also evaluated. The linear isotherms, lack of competitive effects in binary solute systems and similarity of cuticle Kom values to the corresponding Kow values provided strong mechanistic evidence for the role of cuticle as a partition phase in the sorption of NOCs by corn residues. The sorptive capabilities of corn residues and soil organic matter for NOCs were nearly identical as indicated by the similarity of the corresponding Kom values. This suggests it may be unnecessary to distinguish crop residue C and soil humus C when predicting NOC sorption coefficients from the organic C content of soil.