The inflence of humidity and soil type on the degradation process of clomazone, metazachlor and pendimethalin immobilized in the alginate matrix were studied under laboratory condi tions, and herbicidal degradation parameters obtained for alginate systems and commercial formulations (Command 480 EC, Metazachlor 500 SC and Panida 330 SC) were compared. Two soils with different organic content were used in the experiment: loamy sand (S1) and sand (S2). The effect of soil humidity on the rate of herbicide degradation was assessed for soil S1 at 15% and 60% of maximum water holding capacity. Herbicides residues were analyzed using GC/MS method. The experimental data were fited to the mathematical model based on the fist-order reaction kinetics. There was no signifiant effect of soil type on the degradation rate of herbicides immobilized in the alginate matrix. For all alginate systems analyzed process was faster with an increased soil moisture. Formulation is a signifiant factor affecting the degradation process of herbicides in soil.