Researchers demonstrate the effectiveness of using human-derived fertilisers in agriculture. The good climate news is that it reduces environmental impact and offers a sustainable alternative to conventional options.
Good climate news and a major development for sustainable agriculture comes from an unlikely source, the contents of your toilet bowl. New research has shown that fertilisers derived from human waste – specifically urine and faeces – can be as productive as conventional organic fertilisers, without posing any significant risk of disease transmission. This good climate news offers an eco-friendly alternative to synthetic fertilisers, which are responsible for significant environmental damage and high greenhouse gas emissions.
Historically, human waste has been used as a fertiliser due to its high content of essential plant nutrients like nitrogen, phosphorus, and potassium. By reintroducing human excrement into the soil, a more sustainable farming system can be created without significant yield reductions.
Turning human waste to fertiliser is good climate news
Researchers at the University of Hohenheim in Germany conducted a study in which they grew white cabbages using three waste-based products: two fertilisers derived from human urine and one from human faeces called “faecal compost.” The study compared these waste-based fertilisers’ effects to those of a commercial organic fertiliser called vinasse, which is made from sugar-beet and is a byproduct of bioethanol production.
Lead co-author Franziska Häfner confirmed that the fertilisers produced from human urine provided similar yields to conventional fertilisers without any detectable risk of pathogen or pharmaceutical transmission. The urine-based fertilisers resulted in yields comparable or even slightly higher than those of the commercial fertiliser. Although the faecal compost yielded 20-30% less, it improved soil carbon levels, which could maintain long-term fertility. The researchers suggested that combining urine fertilisers with faecal compost would be the most sustainable option, producing yields only 5-10% lower than commercial fertilisers.
To ensure the safety of these fertilisers, the research team screened the human waste for 310 chemicals, such as insect repellants, rubber additives, and flame retardants, and pharmaceutical products. More than 93% of these chemicals were not detected, and the remainder were found at very low concentrations. The study concluded that the risk to human health from pharmaceutical compounds entering the food system through faecal compost use seems low.
According to Dr Rupert Hough, an environmental and soil scientist at the James Hutton Institute in Aberdeen, this study demonstrates that modern treatment methods for human waste have significantly improved its quality, allowing it to be used as a fertiliser without harm. Recycling human waste effectively would require changes to toilet designs, enabling the separation of urine and faeces for nutrient harvesting.
Dr. Ariane Krause, the study’s other co-author and a researcher at the Leibniz Institute of Vegetable and Ornamental Crops in Grossbeeren, Germany, can envision a future where water toilets are replaced with much more sustainable alternatives. She explained that their research supports the findings of several studies conducted in Asia, Africa, North America, and South America and that the next steps are to merge these datasets and conduct a meta-analysis.
This research highlights the potential of human waste-derived fertilisers as an environmentally friendly alternative in agriculture, reducing the need for synthetic fertilisers that contribute to climate change and pollution. This good climate news brings us one step closer to a more sustainable and eco-conscious world.