There is more than 800 000 ha of grassland in Slovakia. Besides its primary productional-function, grassland has also non-productional functions, which are performed mainly by its root biomass. The amount of roots in grassland soils is several times higher in comparison with annual crops on arable land. In grassland soil there is about 7.3 – 8.3 t DM (dry matter).ha-1 of root biomass depending on grassland type, its management and mineral nutrition.
The root biomass of grassland is an important resource of organic matter, which improves soil structure and fertility. A dense rooting of turf layer and a higher humus content are important for better utilisation of soil humidity and cause the high ability to protect soil against nutrient leaching into water resources.
The root biomass is also a resource of nitrogen and other mineral substances. Their accumulation in the root biomass is following: N - 112, P - 11.8, K - 60, Ca - 28 and Mg - 18 kg.ha-1. In the process of mineralisation they become the potential nutrients for the further grassland production. Thus the root system contributes to an organic matter cycle and to the cycle of mineral nutrients in grassland ecosystem.
The root system has also an important role in the environment protection. Besides its erosion-controlling role it also protects the aboveground biomass against the increased concentration of heavy metals, which could penetrate otherwise the food-chain. The roots work as a certain biological barrier of the first contact of the sward plants with heavy metals elements in the soil. There is concentrated the highest level of heavy metals, it decreases in the tillering zone and their substantially lower level was found in the tissues of the above-ground parts of the sward which serve as a feed-food-chain resource.Key-words: environment, grassland ecosystem, heavy metals, root biomass, R/S ratio.