The best part of this type of fertilization is that "it is a very simple process," Pradhan said.
Urine can be collected from eco-friendly, urine-diverting toilets. Or farmers could just collect their pee in cans.
The researchers estimate a single person could supply enough urine to fertilize roughly 6,300 tomato plants a year—yielding some 2.4 tons of tomatoes.
The farmer would just need to give plants ash three days or more after applying urine.
Pradhan and his colleagues are now trying to implement this idea in Nepal, where Pradhan is originally from.
One potential setback may be that pharmaceuticals and hormones excreted in human urine—such as remnants of birth control pills—could negatively impact crops, Pradhan said. For instance, such byproducts could promote antibiotic resistance in local bacteria or get absorbed by the plants.
"However, in small scales in a single family, the pharmaceutical residue present in urine is very low and it can be acceptable," he said.
He also argued that pharmaceutical and hormone residues have been in animal-manure fertilizer for years, and that past studies have not found them to pose a risk to agriculture.
Findings appear in the August issue of the Journal of Agricultural and Food Chemistry.
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