How sustainable is the nitrogen management in Brazil? A sustainability assessment using the Entropy Weight Method.

Nitrogen pollution is one of Brazil's most threatening and challenging environmental problems, caused mainly by productive activities aimed at meeting the demand of food, energy, and housing by a fast-growing population. Sustainable nitrogen management involves optimizing the beneficial effects of reactive nitrogen (N) use and, at the same time, mitigating the negative impacts of its excess on the environment and human health. Here we conduct an assessment of nitrogen sustainability in Brazil from 2000 to 2018 applying the Entropy Weight Method (EWM) to a set of nitrogen-related indicators within four subsystems: environmental, economic, social, and institutional. Our research objectives are to determine an overall Nitrogen Sustainability Index and discuss the relevance of indicators linked to the main anthropogenic sources of nitrogen pollution. By our analysis, the following indicators play a key role in determining nitrogen sustainability levels in the country: political stability, fertilizer consumption, population growth, and investments in water and sanitation. Our findings suggest that political and institutional concerns are greatly impacting sustainable actions towards nitrogen management, leading Brazil to reach only a weak-to-basic level of sustainability in the studied period. We highlight that neglecting the problems caused by the unsustainable nitrogen management can increase environmental, economic, and social issues, and jeopardize the achievement of the Sustainable Development Goals (SDGs). In addition to fostering of sustainability goals on the agriculture and energy sectors from the environmental, socioeconomic, and political perspectives, the importance of this assessment lies in supporting governments, policymakers, and civil society to develop sustainable nitrogen roadmaps to significantly reduce nitrogen waste by 2030, as outlined in the 2019 Colombo Declaration on Sustainable Nitrogen Management backed by the UN Environment Programme.