Indian scientists had taken a patent on cow urine in 2002, convinced about its medicinal values. Now, researchers at the International Centre for Ecological Engineering of Kalyani University near Kolkata report that human urine can be used as safe fertiliser "after eight months of storage under closed conditions."
Urine contains the essential plant nutrients -- nitrogen, phosphorus and potassium -- besides some growth-promoting agents like amino acids, glucose and vitamins, says the report by Bara Bihari Jana and his colleagues published in the Indian Journal of Experimental Biology.
‘The amount of human urine generated daily in a highly-populated country like India can be an important resource if it is managed properly as liquid fertiliser.’
On an average, each person excretes almost six kilos of pure plant nutrients via urine, says the report. "The amount of human urine generated daily in a highly-populated country like India can be an important resource if it is managed properly as liquid fertiliser."
Jana's team had been working for over a decade on the project to test human urine as a replacement for chemical fertiliser. "Earlier we have examined the fertiliser value of human urine for the production of fish food," he told IANS.
In recent years, human urine as liquid fertiliser is getting attention in Europe and in some Scandinavian countries in view of the promotion of organic farming, says the report. The possible presence of disease-causing pathogens in urine had raised some questions. Though storage has been advocated by others for inactivation of bacteria in urine, there has been no study so far to examine this aspect under tropical conditions.
Jana says his latest study aimed at examining the pattern of changes in the counts of coliform bacteria as well as physico-chemical characteristics of human urine during different days of storage under closed conditions in order to identify the optimal storage period of human urine for use as safe fertiliser. The urine for the study was collected from students in the university.
According to the report, the study found that human urine during the storage period "undergoes microbiological and associated chemical changes and becomes highly alkaline", resulting in death of pathogenic bacteria. "We observed that after 253 days of storage under closed condition, the coliform counts were reduced significantly and remained within the safe limit," the report said.
According to the author, human urine is cheaper and more environment-friendly because hazardous chemical compounds or heavy metals such as cadmium are generally absent or low in human urine compared to commercially available fertiliser.
An added advantage is that its use would reduce eutrophication -- the process where fertiliser washed off the land cause damaging blooms of plankton in rivers and lakes.
"With the results of the present study, it may be concluded that human urine can be used as low-risk fertiliser after its storage for 253 days under prescribed conditions," the report said. "Further research and extension activities of this work is necessary," Jana added. "This can be done through NGOs, self-help groups, etc."
But is the scheme workable? Jana believes so. "Human urine may be collected daily in community toilets at airports, railway stations, market places, schools, colleges, etc., and stored in containers labelled with the date of collection," he says.
"The government's current campaign against open defecation and its plans to provide toilets in each village provides the opportunity to implement the concept by making provision in the toilets for collection of urine and faeces in separate chambers."
Would it be practical to truck large volumes of urine around for use in agricultural fields across the country? The answer is "yes", according to the report. "About 80 percent of the nutrients contained in human urine can be concentrated in 25 percent of the original volume by freezing (the urine) which would facilitate transport and storage."