Nitrogenius 2: A web-based decision support system for nitrogen governance and learning

CONTEXT The Netherlands faces an acute nitrogen governance challenge. Intensive agriculture and industry cause freshwater eutrophication, terrestrial acidification, and climate change, while most Natura 2000 areas exceed critical deposition thresholds. A key barrier is limited shared understanding of how nitrogen flows connect ecological, economic, and social processes. OBJECTIVE This paper presents the design and evaluation of Nitrogenius 2, a web-based decision support system and serious game that makes nitrogen system dynamics, trade-offs, and stakeholder interdependencies explicit and accessible. METHODS Nitrogenius 2 integrates activity-based emission accounting, spatially explicit deposition modelling across a 1520-cell grid of the Netherlands, and composite socio-economic indicators within a turn-based simulation covering 2025–2035, incorporating 137 policy measures across four stakeholder roles. Evaluations included a validation test against official Dutch reference data and a classroom deployment at two Dutch universities ( n = 52), complemented by a comparative analysis of environmental-economic trade-offs. RESULTS AND CONCLUSIONS All modelled values fell within 3% of official reference values. Over 80% of participants agreed the system improved their understanding of stakeholder roles and policy complexity, though lower scores on emission-deposition items indicate scope for improving interface transparency. Comparative analysis identified “Switch to Organic Dairy” as the most cost-effective agricultural measure, while targeted buyouts yielded the largest improvement in Natura 2000 protection. SIGNIFICANCE Nitrogenius 2 is an open-source platform bridging the analytical rigor of decision support systems with the participatory strengths of serious games. Its modular architecture supports adaptation to other geographic contexts and environmental policy domains.