Testing the Use of Human Urine as a Natural Fertilizer for Crops

Jun 29, 2022

By Bob Yirka

A team of researchers from several institutions in Niger, Germany and the U.K. has conducted a real-world test of the use of human urine as a natural form of fertilizer for crops. In their paper published in the journal Agronomy for Sustainable Development, the group describes an experiment they conducted with women farmers in the Niger Republic and the use of human urine.

fertilizer

Humans have known for thousands of years that their urine is an excellent fertilizer for crops. It contains phosphorus, nitrogen and potassium—many of the same ingredients as commercial fertilizers. But because of the squeamishness associated with using urine to grow crops, its use has been limited. Still, many gardeners know of its benefits, and thus it is used around the world to help people grow healthy food for their families. In this new effort, the researchers wondered if human urine could be used on a larger scale, such as farms growing crops for sale. They enlisted the assistance of a group of women living in an isolated part of the Republic of Niger. The farmers there have been struggling for many years to fertilizer their pearl millet grain crops, hampered by the cost of commercial products and the scarcity of animal manure.

The first step in the experiment involved renaming urine because its common name was considered offensive. They settled on Oga. Next, they separated the farmers into two groups; one ran their farms in the traditional way, the other fertilized their wheat using Oga. Over two growing seasons, crop yields were measured for both groups. The Oga for the second group of 27 farmers was provided by the farmers themselves, who were taught how to pasteurize, store and dilute their urine for use as fertilizer. They also added small amounts of animal manure.

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Video: Why Your Food Future Could be Trapped in a Seed Morgue

In a world of PowerPoint overload, Rex Bernardo stands out. No bullet points. No charts. No jargon. Just stories and photographs. At this year’s National Association for Plant Breeding conference on the Big Island of Hawaii, he stood before a room of peers — all experts in the science of seeds — and did something radical: he showed them images. He told them stories. And he asked them to remember not what they saw, but how they felt.

Bernardo, recipient of the 2025 Lifetime Achievement Award, has spent his career searching for the genetic treasures tucked inside what plant breeders call exotic germplasm — ancient, often wild genetic lines that hold secrets to resilience, taste, and traits we've forgotten to value.

But Bernardo didn’t always think this way.

“I worked in private industry for nearly a decade,” he recalls. “I remember one breeder saying, ‘We’re making new hybrids, but they’re basically the same genetics.’ That stuck with me. Where is the new diversity going to come from?”

For Bernardo, part of the answer lies in the world’s gene banks — vast vaults of seed samples collected from every corner of the globe. Yet, he says, many of these vaults have quietly become “seed morgues.” “Something goes in, but it never comes out,” he explains. “We need to start treating these collections like living investments, not museums of dead potential.”

That potential — and the barriers to unlocking it — are deeply personal for Bernardo. He’s wrestled with international policies that prevent access to valuable lines (like North Korean corn) and with the slow, painstaking science of transferring useful traits from wild relatives into elite lines that farmers can actually grow. Sometimes it works. Sometimes it doesn’t. But he’s convinced that success starts not in the lab, but in the way we communicate.

“The fact sheet model isn’t cutting it anymore,” he says. “We hand out a paper about a new variety and think that’s enough. But stories? Plants you can see and touch? That’s what stays with people.”

Bernardo practices what he preaches. At the University of Minnesota, he helped launch a student-led breeding program that’s working to adapt leafy African vegetables for the Twin Cities’ African diaspora. The goal? Culturally relevant crops that mature in Minnesota’s shorter growing season — and can be regrown year after year.

“That’s real impact,” he says. “Helping people grow food that’s meaningful to them, not just what's commercially viable.”

He’s also brewed plant breeding into something more relatable — literally. Coffee and beer have become unexpected tools in his mission to make science accessible. His undergraduate course on coffee, for instance, connects the dots between genetics, geography, and culture. “Everyone drinks coffee,” he says. “It’s a conversation starter. It’s a gateway into plant science.”