Dynamic tools unify fragmented 4Rs into an integrative nitrogen management approach

Excerpt

Nitrogen (N) is an essential nutrient for crop production, and the manufacture of synthetic N fertilizer has facilitated impressive advances in food production that have assisted in the avoidance of widespread hunger despite a rapidly growing twentieth century global population. However, this nutrient also causes major environmental concerns, including nitrate (NO₃⁻) contamination of groundwater in agricultural regions and hypoxia and dead zones in estuaries. Also, gaseous forms of N contribute to air quality issues. Nitrous oxide (N₂O), a potent greenhouse gas, contributes to climate change, and ammonia (NH₃) emissions contribute to fine particulate air pollution, a cause of respiratory diseases (Pinder et al. 2007). Anthropogenic N pollution, therefore, has large social costs, with estimated potential ecosystem and health damages of US$157 billion annually (Sobota et al. 2015). Despite many mitigation efforts, the N loss from agricultural systems continues to be a major concern, and in 2017 the hypoxic zone in the Gulf of Mexico reached the greatest extent ever recorded (NOAA 2017).

There is a pressing need to improve the management of agricultural N, and the 4R concept has been proposed as a conceptual path toward more efficient N management (Snyder et al. 2009; TFI 2017). This approach promotes field…