Evaluation of actual sulphur supply in soil and forecast of its development in the Czech Republic

This thesis contains summary information about the importance of sulphur as an important macrobiogenic element in plant nutrition, as well as about sulphur cycle in soil, development of sulphur content in recent years and possibilities of sulphur supply to crops being grown. Sulphur is an important macroelement in plant nutrition and it is part of important amino acids, vitamins and proteins. Sulphur content in crops predetermines the quantity and quality of harvested products. Sulphur in our latitudes entered in soil particularly due to atmospheric depositions. With desulphurization of power plants, there has been a significant decline in sulphur entering soil in recent decades, from an approximate figure of 120 kg of pure sulphur per hectare in 1990 to mere 6 8 kg of sulphur per hectare in 2013. Due to small intake of sulphur in soil, plants that draw off large amounts of sulphur and due to the fact that sulphur is swiftly washed off from the topsoil to deeper soil layers where it is inaccessible to the crops, there is often lack of sulphur in the nourishment of crops being grown, which regards both sulphur demanding crops, such as oil crops, and crops such as cereals where lack of sulphur has not manifested itself as much so far. Soil contains sulphur in an inorganic and organic form. Inorganic sulphur in agricultural land is represented to a lesser extent than organic sulphur, but it is the main source of plant available sulphur and it is a highlydynamic soil component. In soil, it is usually contained in the form of sulphates. Intake of sulphates and their concentration in the soil solution impacts pH, amount of Fe and Al oxides and behaviour of soil colloids. We can influence the content of inorganic sulphur by supplying mineral fertilizers, but we cannot increase the overall long-term supply of sulphur in soil in this way. Long-term and main supply of sulphur in soil is represented by organic sulphur bound in sulphur amino acids, sulfolipids, sulphonic acids and sulphated polysaccharides. We can influence this component of the overall sulphur content by organic fertilization, green manuring, afterharvest residues and sewage sludge application