Human and cattle urine is rich in key nutrients required for plant growth, including nitrogen, phosphorus, potassium, calcium, and magnesium. These essential nutrients, when properly harnessed according to the principles of ‘nutrient in a circular economy’, have the potential to sustainably replenish soil fertility and food production in a sustainable manner. In this article, we share our perspective on how to manage human and animal waste that can be efficiently converted into fertilizer based on a scientific literature review carried out by a Bhutanese PhD researcher investigating the efficiency of converting animal waste to fertilizer. 

A balanced nutrient ratio in human urine offers the right condition to be used as a fertilizer. Applying urine to crops also provides the plants with nutrients in a readily available form for its utilization. Using human urine as a fertilizer can also contribute to sustainable waste management practices. For instance, by diverting urine away from wastewater systems, we can reduce the strain on sewage treatment facilities and save energy and operational costs for wastewater treatment plants. On average, a person can produce about 800 to 2,000 ml of urine in a day,  depending on an average daily fluid intake of about two litres. 

At cattle farms, the animal’s urine could also provide an opportunity to link cattle farms with crop production providing effective management of animal waste as per the principles of the circular economy. On average, a cow excretes 13 to 14 litres of urine daily. Currently, the production of farmyard manure in Bhutan is less effective as significant quantities of nutrients are lost through leaching at the cowsheds. The leached nutrients at times discharge into nearby water bodies leading to contamination of water sources. Exploring options to redesign cattle sheds to improve efficiency in nutrient collection is an opportunity for improving Bhutan’s agriculture production. However, it should be noted that such options may come in conflict with other priorities such as the production of biogas from animal waste.

On-site urine diversion, collection, and treatment systems in a village or a town can be initiated. Once collected the urine needs to be fermented. Subsequently, it needs to be treated with approved technologies such as membrane separation, bio-electrochemical technologies, struvite precipitation, ion exchange, and electrodialysis, etc. Research has shown that such plants were cost-effective and successfully implemented in farmlands outside Paris. Dried urine converted into fertilizer pellets has been under trials on farmland outside Paris using urine collected from urinals or specially designed toilets and channeled into a dryer, where an alkalising agent, such as calcium or magnesium hydroxide, raises its pH (Simha et al. 2020). Any water in the now alkaline urine is evaporated and only the nutrients are left behind.

The initial expense of converting urine into fertilizer requires capital investment, which is often cited as the main challenge. But numerous studies indicate that compared to importing synthetic fertilizers and burdening treatment facilities, investing in the conversion of human urine to fertilizer is a significantly more sustainable and cost-effective option. Further, by opting for urine as an organic alternative, we reduce the dependency on synthetic fertilizers. Synthetic fertilizers are generally produced by converting nitrogen in the air to ammonia, which alone consumes two percent of the world’s energy and relies heavily on fossil fuels, or by mining finite resources, like phosphate rock (Simha et al. 2020).

Given the right balance of nutrient ratios and the right chemical composition of nutrients, urine-based fertilizers are easily utilized by plants. Thus, contrary to chemical fertilizers, the loss of nutrients to wash-downs is minimal. The minimal leaching of fertilizers is critical for the protection of water sources.  

Researchers in India conducted field trials and reported that farmers were able to produce fertilizer from cow urine with relatively cheaper and straightforward techniques. Use of the fertilizer is also associated with increased self-sufficiency, improved social capital, and enhanced autonomy in income for vulnerable groups such as women farmers.

As a group of researchers, we believe raising awareness and sharing scientific information on organic fertilizer production could be an option to explore the opportunities of urine-based fertilization production. Any relevant public or private individuals could start establishing a fertilizer production plant to test benefits, adapting the plant and process to the Bhutanese context, and then sharing the best practices to be adopted for a sustainable approach at a larger scale. Collaborating with agricultural experts, extension services, and research institutions can help provide accurate information and guidance on urine application techniques. Developing and proposing urine collection technologies could also involve engaging toilet manufacturers, urban developers, product regulators, and plant operators. As a team, the most appropriate design of a decentralized system of separating urine could be explored. Hopefully, in the long-term effective nutrient management can significantly contribute to sustainable agriculture practices, soil fertility improvement, and responsible waste management. 

The article is published based on personal experiences and observations by a group of water researchers from Bhutan. The group can be contacted at