Molecular complexes of peloids enter the soil structure, and their presence highly increases the exchange capacity of the soil. Adsorbed forms of nutrients do not bind with soil and are not washed out with water, so they are available for nutrition of plants. Plants use these adsorbed substances more intensively than nutrients of the soil solution. The humic substances are able to prevent the fixing of potassium by clayish minerals due to the formation of chelate-type compounds. Useful minerals, being metals, together with molecules of humic compounds form chelates in soil and penetrate plants, providing them with nutrients, and iron and manganese, according to some scientific soil researches, are absorbed by plants only in the form of organically bonded complexes.