Soil‐Conditioning Properties of Modified Agricultural Residues and Related Materials: I. Aggregate Stabilization as a Function of Type and Extent of Chemical Modification

The feasibility of producing soil‐conditioning agents from agricultural residues by chemical modification was investigated. Such reactions as xanthation, cyanoethylation, methylation, hydroxyethylation, sulfation, phosphorylation, acetylation, and oxidation were applied to wheat straw, corn stover, corncobs, bagasse, rice hulls, and their major components. From results of comparative reactions on cellulose, hemicellulose, and lignin, the major part of the soil‐conditioning activity of chemically‐modified agricultural residues was found attributable to the substituted cellulose fraction. The extent of substitution required to produce active products varies with the nature of the derivative but coincides in all cases with that required to give water‐soluble products. Within these limits the degree of polymerization has more influence on aggregate‐stabilizing activities than either the type or extent of substitution. Data on a number of microbial gums, plant polysaccharides, and starch derivatives are also presented.