Contaminated runoff from the excessive use of nitrogen and phosphorus is problematic in freshwater systems and also presents significant risk from the flow of these systems into the ocean. Such flows of phosphorus have the potential to lead to large-scale ocean anoxic events (insufficient dissolved oxygen in the ocean), which have previously been associated with mass-extintion events. Similarly, excessive flows of nitrogen into the ocean cause eutrophication of aquatic ecosystems, wherein excessive algal blooms create dead zones and fish kills.

A few agricultural regions globally with very high fertiliser use have historically contributed disproportionately to Nitrogen and Phosphorus Loading. However, excess fertiliser use in any location contributes to global and local risks.

Global to local connections

Our waterways are vulnerable to the effects of Nitrogen and Phosphorus Loading, which makes this both a global and a local issue to address. Minimising the effects of Nitrogen and Phosphorus Loading in Greater Melbourne can be achieved through regenerative farming and related methods that focus on alternatives to synthetic fertilisers to build soil health. This includes shifting agricultural activities occurring in the metropolitan area, as well as incresing consumption of products grown regeneratively outside of the city.