Soil-applied herbicides adsorption

Gaillardon, P., J.C. Gaudry, and R. Calvet (1981). Adsorption des herbicides par des acides humiques Remarques sur les sites d adsorption et le role cations fixes sur les acides humiques. In Proceedings of Symposium on Theory and Practice of the Use of Soil Applied Herbicides. Paris European Weed Research Society, pp. 3-9. 

This coefficient can be applied to all nonionic organic chemicals. Soil organic matter analysis has shown that approximately 58% is organic carbon,and a multiplication factor of 1.724 is therefore used to convert organic carbon to organic matter. Koc is an adsorption coefficient which describes the adsorption of a herbicide to soil based only on the properties of the molecule and therefore can be used to compare the relative amounts of adsorption of different herbicides. Table 7.1 gives some values reported... 

Many organic substances, notably fertilizers, herbicides, insecticides and fungicides, are applied to soils more or less regularly. The organic fertilizers include chiefly nitrogenous materials that are decomposed readily to ammonia and present no important problems with respect to adsorption apart from fixation of the ammonium, discussed in Chapter 11. It is the pesticides that are of most interest since they are being used in ever-increasing amounts and since some of them may persist in soils for many weeks and months. 

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