The agricultural nitrogen surplus in the danube river basin- development from 1980 to 2021

Nitrogen is a key nutrient essential for plant growth in agriculture, playing a central role in ensuring adequate food supply to meet rising demands of a growing population. Technological innovations such as the Haber-Bosch process enabled the synthesis of ammonia (NH3) from nitrogen gas (N2) and hydrogen gas (H2), forming the basis for the production of inorganic fertilizers. Without this process, the level of global food production needed to sustain the world population would not be attainable. Mismanagement or overapplication of inorganic fertilizers, however, leads to a nitrogen surplus in the soil, which carries the risk of fortifying environmental pressures such as eutrophication of surface waters, N2O emissions, or acidification of soils. Hence, there is an urgency to safeguard the appropriate use of inorganic fertilizers in agriculture, ensuring that the nitrogen surplus in the soil is mitigated.This thesis outlines the development of the nitrogen surplus in the Danube River Basin, at the example of Austria, Hungary, and Romania by calculating the respective surplus for each country from 1980 to 2021. In doing so, the research examines the impact of geopolitical events – i.e. the dissolution of the Soviet Union in 1991 – and implemented EU agricultural policy provisions on the nitrogen surplus development. To calculate the agricultural nitrogen surplus in the three countries, the OECD method is applied, whereby the nitrogen surplus is determined as the difference between nitrogen input flows and nitrogen output flows. The research concludes that both geopolitical events and enacted EU agricultural policy have influenced the development of the nitrogen surplus in the three countries observed. The former induced lower inorganic fertilizer application rates, while the latter contributed to a higher nitrogen use efficiency (NUE) of nitrogen input flows, particularly inorganic fertilizers.