Nitrogen flows in the food production chain of Hungary over the period 1961–2010

Nitrogen (N) emissions from food production can cause serious environmental problems. Mitigation strategies require insights of N cycles in this complex system. A substance flow analysis for N in the Hungary food production and processing chain over the period 1961–2010 was conducted. Our results show that the history of the total N input and output for the Hungary food chain consists of four distinct periods: 1961–1974 a rapid increase; 1974–1988 a steady increase; 1988–1992 a sharp decrease; 1992–2010 a period of large annual variations. The total N input to the food chain largely depended on N fertilizer input (on average 83 % of total input). Nitrogen losses were the largest outflows, particularly via ammonia emissions and denitrification from agricultural systems. The N use efficiency (NUE) for crop production sharply decreased from 1961 to 1974, but went up since the late 1980s. The NUE of animal production increased from 11 % in 1961 to 20 % in 2010. The N cost of food production in Hungary largely varied from 3 to 10 kg kg⁻¹ during 1961–2010, which was related to changes in fertilizer use and human dietary preferences. Increased dependence of crop yield on weather was observed since the early 1990s where large decrease in N fertilizer use occurred. The observed weather-dependence has resulted in large yearly variations in crop yields, the NUE of crop production and also the food N cost, which may pose a threat to food security of Hungary.