Smallholder farmers grappling with the high cost of fertilizer for use in their farms can use human urine which has been identified to only promote plant growth as well as industrial mineral fertilizers, but also would save energy used on sewage treatment.

Human urine is naturally rich in nitrogen, potassium and phosphorus – the same ingredients in conventional fertilizers.

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According to Pradhan and Heinonen-Tanski, who are environmental scientists at the University of Kuopio, Finland, they grew the beets as an experiment in sustainable fertilization. They nourished the root vegetables with a combination of urine and wood ash, which they found worked as well as traditional mineral fertilizer.

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The beets fertilized with urine were 10 percent larger, and those fertilized with urine/ash were 27 percent larger than those grown in mineral fertilizer. As for nutrient content, all the beets were similar, and in a blind taste test the beets were rated as equally flavorful.

"It is totally possible to use human urine as a fertilizer instead of industrial fertilizer," says Heinonen-Tanski, whose research group has also used urine to cultivate cucumbers cabbage, and tomatoes. Re-cycling urine as fertilizer could not only make agriculture and wastewater treatment more sustainable in industrialized countries, the researchers say, but also bolster food production and improve sanitation in developing countries.

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The research is provided by Scienceline, a project of New York University's Science, Health and Environmental Reporting Program.

Farmers intending to use urine to fertilize their farms should feel free to do so. They should keep in mind that urine should be diluted with water at least 10:1 for most plants and should be separated from solid waste to avoid contamination. It is advisable to collect urine in a bottle or bucket. You can also add urine to your compost heap to enhance its nutritional content.

A 50kg bag of CAN fertilizer costs between Sh2, 500 and Sh3, 000 in Kenya thus farmers can save on this amount per acre in their farms.