Sustainable agricultural soil management by recycling algal biomass to land

Emanga Alobwede

Emanga’s project at the Grantham Centre

Intensive agriculture depletes soil organic matter, resulting in loss of soil macro-aggregates and their positive effects on soil water and nutrient holding capacity. Soil degradation now limits the productivity of elite modern high-yielding varieties of crops like wheat. Furthermore, loss of soil structure increases risk of flooding and run-off pollution. Run-off pollution leads to nutrient enrichment of aquatic systems and algal blooms. Algal blooms cost the UK an estimated £75-114 million per year. The increased application of fertiliser further exacerbates the problem of eutrophication and a major concern for future food security is that phosphorus originates from limited rock reserves.

Recovery of algae from polluted lakes and ponds has the potential to break the eutrophication cycle and the technology to do this efficiently is only now being developed. Once recovered, the algal biomass has a variety of uses including addition to soils. Benefits include increasing soil nutrient content, structure, aggregate stability and fertility, whilst reducing nutrient-run-off to watercourses compared to direct additions of manures or inorganic fertilizer. To date there have been no systematic studies of the properties of algae that optimise these benefits. This project aims to link the recovery of algal biomass from eutrophic water to the restoration of soil organic matter, rebuilding soil aggregates and sustainably recycling nutrients.

Research groups

Emanga is part of the Algal Biotechnology Sheffield Network.


Emanga on the BBC's Horizon: Feast to Save the Planet
Emanga on the BBC’s Horizon: Feast to Save the Planet

At the start of 2021, Emanga appeared on the BBC programme Horizon: Feast to Save the Planet.

The episode focused on the environmental impact of food, with special guests eating meals that explore some of the complexities of sustainable food. Emanga was on the show to explain how her research into algae has implications for our diet. For example, algae could help us reduce our reliance on synthetic fertilisers and improve degraded soils. You can watch the episode on IPlayer.


Circular economy fertilization: Testing micro and macro algal species as soil improvers and nutrient sources for crop production in greenhouse and field conditions

Social media

You can find Emanga on Twitter @EmangaAlobwede


Dr Jagroop Pandhal

Department of Chemical and Biological Engineering


Professor Johnathan Leake

Department of Animal and Plant Sciences