Engineering novel phosphorus fertilisers: Liberation of phytate phosphate from human waste as a sustainable fertiliser

Niall Bradshaw

Niall Bradshaw, speaking at the UN Conference on Climate Change in Marrakech.

Low phosphate availability in soil often limits crops’ ability to grow, a problem that is often managed by applying commercial fertilisers. This approach is unsustainable as, at current rates of use, non-renewable global stocks of phosphate used in these fertilisers are estimated to last only 150 years. An alternative is therefore urgently required.

One option is the large amount of phosphate present in organic fertilisers such as human and animal waste, but it is locked within phytate, a molecule that plants produce but cannot absorb from the soil. Normally, phosphate is released from phytate by the actions of soil microbes. But agricultural practices have, over time, removed many of these microbes from the soil, so the phosphate cannot be unlocked as easily, making organic fertilisers less effective than they could be.

This project aims to increase the nutritional value of organic fertilisers by releasing phosphate from phytate using the enzyme phytase. The project will trace the progress of phytate from the plant, through the animal that eats it, into the soil where it is left as waste, and identify the point where phytase should be introduced to release the valuable phosphates for use by the plant. The goal is to develop a phytase-based treatment for organic fertilizers, ultimately increasing crop yields and improving the sustainability of crop production worldwide.


In this blog, Niall Bradshaw explains the threat of finite phosphate reserves, and captures the discussion he led with other first year Grantham Scholars at their weekly Journal Club. Read: Fighting for phosphorus.

Scientists and engineers from the University of Sheffield helped world leaders shape a more sustainable future at the successful United Nations conference on Climate Change in Marrakesh 2015. Niall Bradshaw spoke on a panel about sustainable agriculture. Read more.

Neil wrote about his experiences at Marrakesh in a blog for the Grantham Centre. Read: Impressions from COP22: Time is of the essence.


Dr Robert Falconer

Department of Chemical and Biological Engineering


Professor Duncan Cameron

Department of Animal and Plant Sciences