Production function of agricultural ecosystems provides not only food and feed but also determines further ecosystem functions and services. Production from agricultural ecosystems consist of economically used and at present unused phytomass. State and development in economically used and unused agricultural phytomass in Slovakia was set up by material flow analysis introduced by Eurostat. The method offers new comprehensive view at natural resources utilisation, including biomass. The system of material flow accounting and derived indicators is descriptive tool aimed at information on the overall material inputs into and outputs from the economy / from the process. There were derived related indicators and completed material balance of cereals which indicates potential in utilisation of phytomass in other economy spheres, e.g. in energy for heating or biofuels production.