In this textbook the author has sequentially described the history of soil chemistry, application of soil chemistry in agriculture, chemical properties and composition of the principal types of soils, important chemical processes and chemical equilibrium in soils, fundamental laws of ion-exchange capacity of soils, formation of acidity and alkalinity as well as oxidation-reduction conditions. Also described are the principles of structure and formation of specific humic compounds and clay minerals. The author also examines the applied problems of chemical amelioration of soils and soil pollution.