Dear all
My comments are
- Move beyond the ‘4R’ as these represent an ideal framework only but are unrealistic with current fertiliser technology.
- Make regulating nutrient losses a priority as N2O emissions and water pollution are globally felt and pose strong risks. Develop a risk matrix with view of the risks of losing fertilisers with view of soil, climate, crops.
- Consider nutrients in a broader crop system context with mineral fertilisers, repurposed nutrient-rich wastes, N-fixing plants for a holistic approach to nutrient supply of crops and soils.
- Consider the benefits of improving soil with the addition of organic carbon bound to nutrients (soil biological function, improved root growth, building of soil organic matter etc).
- Consider amelioration of wastes: most are not ideal crop nutrients with to too fast/too slow release patterns, toxicity, unbalanced nutrient stoichiometry etc. mixing several wastes, adding sorbents (geosorbers, biochar) and other manipulations will be needed.
- Consider nutrients beyond NPK, as micronutrient deficiencies are more becoming more common and often the effects seen with higher NPK addition is in fact a response to micronutrient ‘contaminants’ in NPK fertiliser, such as Zn.
- Request more comprehensive testing and long-term experimentation, local farmers experimenting and involvement of the community to ensure knowledge generation with stakeholder involvement.
- Consider the circular nutrient economy to recycle nutrient-containing wastes at local and regional scales.
- Advance the next-generation fertiliser concept with aim to optimise nutrient source and release patterns driven by crops rather environmental conditions.
Best wishes
Susanne
Susanne Schmidt