Research of the ReNu2Farm project was presented at the Annual Conference of the Microbiology Society, running from the 26th to the 30th April. The conference is one of the largest gatherings of microbiologists in Europe with usually over 1,600 attendees, presenters, speakers, researchers, and industrial partners. The conference was hosted online, and comprised many different topics such as antimicrobial resistance, environmental and applied microbiology, genetics and genomics, marine microbiology, public health microbiology, RNA & DNA viruses, SARS-CoV-2 viruses, and the COVID-19 pandemic.
The poster presented by Lea Deinert from University of Limerick contained information about the microbial P cycling of recycling-derived fertilisers (ashes and struvites) in a pot trial and a subsequent microcosm trial a year later. It demonstrated that struvite application leads to higher dry matter yields than commonly used super phosphate (SP) fertilisers during the pot trial. Furthermore, SP fertiliser had a negative effect on the microbial community involved in P solubilisation from tri-calcium phosphate in the short term. The acid phosphatase activity in soil was enhanced by the struvite and SP application at a high P rate, while the poultry litter ash showed no difference to the control, indicating that the ashes have the potential to reduce acid phosphatase activity due to their liming effect. However, during the second year this effect was not observed again. Instead, the ashes showed higher gene copy numbers for acid (phoC) and alkaline phosphatases (phoD) in a qPCR analysis and also the microbial P mobilisation from phosphonates and phytate, tested in cultivation experiments, was improved in the ash treatments compared to the SP fertiliser. The shift in the alkaline phosphatase community was also confirmed in a phoD next-generation sequencing analysis for the microcosm trial. In summary, the struvites perform similar to the SP fertiliser in most aspects in the short term, while the ash fertiliser application is beneficial for the P cycling microbial community, by facilitating a continuous P supply for plant growth in the second year.