WP2: Innovative recycling P fertilizer

Phosphorus supply from alternative phosphorus fertilizers (APF) will need to be balanced against environmental impacts which can be assessed using Life Cycle Assessment (LCA) approaches and modeling of the risk of soil accumulation of pollutants (currently only available for digestates and composts from municipal organic wastes). The overall objective of WP2 is to assess the chemical bonding of P and P bioavailability of different APF in field, pot and growth chamber experiments, and to develop and evaluate sustainable solutions for increasing P-recycling. At the same time, we will evaluate the potential environmental impact of the APF.

Following tasks comprises WP 2: Evaluation of efficacy and potential environmental impacts of alternative P fertilizers

Task 2-1: Chemical characterization of alternative P fertilizer and assessment of their plant P availability in pot and greenhouse experiments

Chemical extraction and fractionation techniques for identifying P forms and anion/cation exchange resin extraction assays for estimating P availability of potential APF will be performed. In addition, growth chamber experiments using APF will be conducted with L. multiflorum, Z. mays and T. pratense as a model species.

For more details please contact Iris (Minze) Wollmann and/or Gregor Meyer.

 Task 2-2: Field experiments on P-availability and P use efficiency of alternative P fertilizers and their technical application

The most promising P fertilizers identified in Task 2-1 will be tested under field conditions for their effects on plant biomass growth, crop yields and nutrient uptake of wheat and red clover. This will be combined with different application techniques (band application near plant roots vs. broadcast application) to assess the effects of these application techniques, along with the application of PGPR in selected experiments (in cooperation with WP3).

For more details please contact Iris (Minze) Wollmann and/or Gregor Meyer.

Task 2-3: Life cycle assessment of alternative P fertilizers (FiBL-AT)

The aim is to evaluate APF using LCA indicators. The most promising APF will be evaluated throughout their whole life cycle from production to field application and compared with each other. Furthermore, if useful data is available, uncertainties concerning the LCA evaluations can be characterized.

For more details please contact Stefan Hörtenhuber.

Task 2-4: Assessment of the risk of long term soil accumulation of pollutants due to regular application of APFs, and development of an evaluation tool to assess contamination levels in relation to the benefits provided

APF can contain pollutants like heavy metals, organic pollutants, antibiotics and others. Also human pathogens may be contained. Regulations on suitability of APF are based on pollutant content on a dry matter base. However, fertilizer nutrient contents vary in a very wide range and application is usually based on their nutrient loads and not on the applied amounts of dry matter. Therefore, the risk of accumulation of pollutants is influenced mainly by the amounts of nutrients applied to the soil. The aim of this task is to assess the risks of accumulation in soil and crop uptake of these contaminants by modeling the input and output flows over a period of 100 years. Furthermore, we will compile and discuss approaches to assess the risks of application of P fertilizers in relation to the benefits (e.g. pollutant flows per unit nutrients or nutrient equivalents, heavy metal-nutrient index, heavy metal-P index, etc.) to provide a tool for comparison of different APF.

For more details please contact Jürgen Friedel and/or Kurt Möller.