Lunch Seminar "Plant nutrients as a resource – nitrogen vs. phosphorus, taking sulphur and potassium into account"

Within the area of food waste, the Swedish environmental quality goal system proposes the goal “Economizing on resources in the food chain (Resurshushållning i livsmedelskedjan)” and within this, the subgoal “Recycling 60% of the phosphorus in wastewater to productive land by 2015”. This raises the questions: Is phosphorus the most important resource in wastewater? Is phosphorus even an essential part of the resources in wastewater, considering the amounts of nitrogen, potassium and sulphur contained in wastewater?

In the seminar a number of ways of evaluating the importance of the different plant nutrient resources (N, P, K and S) are explored. They all point at nitrogen, not phosphorus, as being the most important resource. This means that the proposed wording “Recycling 60% of the phosphorus in wastewater to productive land by 2015” probably drives development away from, rather than towards, sustainability. Discussion on the topic are welcome during the seminar.