Human Waste Fertilisers Could Boost Dryland Farming and Support Sustainable Food Systems

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• Researchers suggest that treated human waste fertilisers could provide essential nutrients for crops, offering a cost-effective alternative to synthetic inputs in dryland farming.
• The approach has the potential to improve soil fertility and water retention in arid regions, where resource scarcity hampers agricultural productivity.
• Using human waste in a safe, regulated manner supports circular economy principles, reducing dependence on chemical fertilisers and lowering environmental impact.
• Adoption of this practice could strengthen sustainable food systems by enhancing yields, cutting costs for farmers, and recycling valuable nutrients back into the soil.

Dryland farming, often hampered by scarce water and poor soil fertility, may find new life through the use of human excreta-derived fertilisers. 

A recent study published in Frontiers in Sustainable Food Systems highlights their potential to improve crop performance, strengthen soil health, and advance a circular bioeconomy.

The research, led by William Musazura of the University of KwaZulu-Natal in South Africa, investigated the benefits and safety of sewage sludge-based co-compost and urine when used as fertilisers. 

“We were particularly interested in understanding the agronomic performance and environmental safety of these materials,” Musazura explained. His team conducted a six-month field trial using a randomised block design to compare five treatments: urine, urine combined with co-compost, chicken manure, conventional fertiliser, and a control with no fertiliser.

Findings revealed no major differences across treatments in chilli yield, soil nitrogen dynamics, enzyme activity, microbial diversity, or active carbon. 

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However, the urine plus co-compost and chicken manure treatments significantly increased soil organic carbon and extractable phosphorus. “This suggests that excreta-derived amendments can enhance soil organic carbon and phosphorus without compromising groundwater quality,” Musazura said.

The implications go beyond soil science. Human waste fertilisers could reduce reliance on synthetic alternatives, cutting the energy demands and emissions associated with industrial fertiliser production. 

By recycling nutrients, these practices also align with regenerative agriculture principles and contribute to closing nutrient loops.

The study does, however, stress the need for careful management. “Safe use of these materials requires salinity control and adherence to WHO sanitation guidelines,” Musazura cautioned. Strong regulatory frameworks and clear best-practice standards will be essential for their safe adoption at scale.

Researchers also acknowledge the study’s limitations, noting its short duration and single-site scope. They call for long-term, multi-location trials to better understand broader agronomic, environmental, and soil health outcomes.

As global agriculture faces mounting pressures from climate change and rising food demand, excreta-derived fertilisers may represent both a practical and sustainable path forward. 

For Musazura and his colleagues, the message is clear: rethinking waste is not only possible but essential to building resilient food systems for the future.