Project RELACS – Improving inputs for organic farming. On many organic farms, especially those without livestock, phosphorus (P) exports through the sale of produce is greater than P imports through fertilisers and purchased animal feed. While soil P reserves from residual fertiliser applied before conversion to organic farming can often deliver P for decades, mining of soils is unsustainable in the long term.

Many bio-resources, such as digestates and composts, contain P from various organic wastes. Wastewater treatment plants are a major sink for P as well. There are many options under development to recycle P from these waste streams. Some are already permitted in organic agriculture.

Closing nutrient cycles is at the core of organic agriculture. Replenishing soil P reserves will prevent deterioration of soil fertility and sustain good productivity.