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Putting Phosphorus First

I recently returned from the ninth International Phosphorus Workshop (IPW9) in Zurich, Switzerland. More than 230 delegates from 31 countries gathered at ETH Zurich, a science and technology university of about 21,000 students. The theme of the workshop and focus of the delegates was “Putting Phosphorus First: How to address current and future challenges.”


Campus of ETH Zurich University

The campus of ETH Zurich University, the site of the 9th International Phosphorus Workshop.

by Jango Bhadha, assistant professor, Soil and Water Sciences Department, Everglades Research and Education Center

For three days, sessions were held in the mornings, afternoons, and evenings. These covered topics such as efficient use of phosphorus in agroecosystems, environmental phosphorus problems, and sourcing phosphorus fertilizers. Most noteworthy, there was a lot of talks related to phosphorus in agroecosystems.

Opening Keynote Lectures:
• Andrea Ulrich, ETH Zurich / PhosAgro Trading SA, Switzerland. ‘The importance of adequate phosphate rock quantity and fertilizer quality in the 21st century’
• Genevieve Metson, Linkoping University, Sweden. ‘A need to better integrate substance flow analyses into transdisciplinary spaces for transformative change in phosphorus recycling’
• Anders Nattorp, University of Applied Sciences and Arts Northwestern Switzerland, Switzerland. ‘How to transform a phosphorus waste stream into a fertilizer’
• Therese McBeath, CSIRO Agriculture and Food, Australia. ‘Strategies for efficient phosphorus use in crop and pasture systems’
• Helen Jarvie, NERC Center for Ecology & Hydrology, Wallingford, UK. ‘350 years after phosphorus discovery: Addressing environmental challenges of phosphorus deficiencies and excesses’

We also had an opportunity to venture off the ETH Zurich campus. Organizers planned five excursions, from which participants could choose one: options to mitigate phosphorus losses from land to waters in an area with high livestock density (Midland Lakes/P losses); nutrient recovery from source-separated waste streams (Eawag/On-site sanitation) – supported by Laufen; phosphorus, a limiting nutrient in Swiss forests (WSL/Swiss forest); producing biomass from wastewater (Wädenswil/Aquaponics) – supported by Hach; mitigation measures for soil erosion – a success story in the Canton of Bern (Bern region/Erosion) – supported by BGS; and phosphorus in Swiss agriculture: Sources, rates, and fertilization guidelines (Reckenholz/P fertilization) – supported by Hauert.

Wastewater to Biomass

I chose the trip on producing biomass from wastewater. It began with a long journey by boat across Lake Zurich. I noticed picture-perfect vistas surrounding the lake, and the lake water quality was good.

boat ride on Lake Zurich, Switzerland

A boat ride across Lake Zurich, Switzerland.

In about an hour, we were at The Zurich University of Applied Science (ZHAW) in Wädenswil, which is investigating the recovery of nutrients through an ecological engineering approach. During this excursion, we visited two water-based systems – a large scale aquaponics system and a recirculating raceway for algae production. Likewise, we also witnessed how biochar is produced from fecal matter in a pyrolysis reactor. The biochar ultimately ends up as an element of a land-based recycling approach.

aquaponics lab

A large scale aquaponics system and a recirculating raceway for algae production.

poster on turning fecal matter into biochar

Technology that converts fecal sludge into biochar.

Research Posters

Two afternoons of the workshop were set aside to accommodate the 109 poster presentations. These were related to the topics covered in the parallel session. Some very interesting topics were discussed during the poster sessions, including how to derive fertilizer from urine, and the influence of pH change on the phosphorus cycle in aquaponics.

Research posters on efficient phosphorus use.

Posters presented in the session titled ‘Efficient P use in agroecosystems’.

My presentation was “Phosphorus use efficiency through sustainable agricultural practices in South Florida.” This topic falls under the workshop subtheme of phosphorus use in cropping and farming systems. This research highlights how farming practices in the Everglades Agricultural Area of South Florida have long been mindful of phosphorus management as it relates to sufficiency and efficiency of phosphorus utilization. Some of the research initiatives presented included the use of local agricultural and urban organic residues as amendments on sandy soils to grow sugarcane; cultivating flooded rice as a treatment technology to reduce phosphorus loads; evaluating phosphorus use efficiency in crop management by identifying and selecting varieties tolerant to low P inputs in rice and lettuce cultivars.

Key Questions

Over the course of the workshop, participants were asked to reflect on three key questions:

  1. Where have we made substantial progress over the last 5-10 years and where did we stall despite early promises?
  2. What are the current and future key research questions in the field of phosphorus research?
  3.  Identify some of the most promising methods/approaches for tackling these questions?

The general consensus was that there has been substantial progress in the field of identifying sources of phosphorus contaminations, and significant progress in the field of phosphorus analyses. However, areas where key research questions still exist is in understanding how phosphorus is being metabolized by plants and animals, and its functions in plant/animal physiology. Other areas that have not been fully addressed are phosphorus acquisition efficiency (PAE) and phosphorus use efficiency (PUE). Some of the promising methods/approaches to look forward to in the future is the use of precision agriculture in phosphorus application and the application of genomics and gene-editing in addressing PUE.

Wrapping Up

The final day featured two keynote lectures. Hansjorg Grutzmacher of ETH Zurich spoke about ‘Building blocks containing phosphorus from atom efficient syntheses.’ Christophe Lasseur with the European Space Agency talked about ‘Mars mission the ultimate example of circular economy.’ Closing remarks were presented by Emmanuel Frossard of host university ETH Zurich.

At the end of the five days, participants were treated to a farewell dinner at the Lake-side Restaurant in Zurich accompanied with good food, drinks, and local entertainment. A big thank you to the organizers, ETH Zurich, and the city of Zurich for their hospitality. I’m looking forward to IPW 10.

group photo of 9th international phosphorus workshop participants