Nitrogen and phosphorus transport in the soil from the point of view of water pollution

Anotace: Soil functions are very important parameters of soil quality. The transport soil function plays a dominant role in terms of transport and accumulation of substances in a vertical and horizontal direction in the soil. The aim of this paper is to evaluate the soil transport function on the base of present knowledge of nutrients (nitrogen and phosphorus) transport in the soil. The soil transport functions were classified in five categories: (1) very weak, (2) weak, (3) moderate, (4) strong and (5) very strong. By this way is known from which localities can come the possible risk for water pollution. Moreover, it is very important at observance of the Nitrate Directive. The farmers can harmonise the nitrogen fertilisation with the soil categories. The result of this paper is the creation of the areas of individual categories of soil transport function in agricultural soils in Slovakia according to the soil transport function information. In case of nitrogen, more than 88% of the area of agricultural soils belong to the categories with very weak, weak and moderate transport. To these categories belong the deep soils (more than 0.6 m depth) with neutral soil pH and sufficient content of high quality organic matter, without the gravel in their horizons, which are located on the plains especially on warm south-west and south-east parts of Slovakia. The strong and very strong nitrogen transport is detected only in 11.4% of the soils in Slovakia. In case of phosphorus, in 73% of agricultural soils was recorded very weak, weak and moderate transport. In almost 27 % was recorded strong and very strong phosphors transport. To these soils belong shallow soils (less than 0.3 m depth), acid soils with low quality humus and with high content of gravel, which are located in alpine region mainly in northern parts of the country. In these localities can come to increased content of phosphorus in the water bodies and thus also to a decrease in water quality. Generally, soil transport function has extraordinary importance in term of water resources protection. The more pollutants are transported from the soils, the bigger is the danger to pollute the water.