Using human urine as natural fertiliser

By Maore Ithula

Did you know that an average adult has sufficient fertiliser to produce a whopping 2.41 tonnes of tomato in a single season?

Indeed research in Finland two years ago established that urine produced by an adult over a year is enough to grow 160 cabbages or about 64kg more than could be grown in a similar plot of land fertilised with commercial fertiliser.

In the continuing effort to achieve food security, the Jomo Kenyatta University of Agriculture at Technology (Jkuat) is carrying out a study on the use of human urine as a fertiliser. The scheme is expected to be complete in less than two months just in time for the next planting season.

Urine fertiliser is environmentally friendly as it is free of heavy metals unlike chemical fertilisers.

Jkuat vice-chancellor and Prof Mabel Imbuga, says in less than two months, a formula of how to exploit urine, as a source of fertiliser will be ready for commercialisation. "an average person’s urine output is between one and two litres per day or between 50 and 60 millilitres per hour," says Imbuga, a biochemistry specialist.

Tomato fruits

In a household, a family of four produces enough urine to fertilise a third of an acre at a rate comparable to the application of conventional fertiliser of 100kg per hectare in the developed countries.

"In one year, the average human being produces enough urine to fertilise 6,300 tomato plants which would produce 2.41 tonnes of tomato fruits in just one season," says the professor of biochemistry.

But the high nitrogen content in urine actually "burns" any plant it comes in contact with.

The urine must be diluted, says Imbuga. Although it is being introduced in Kenya for the first time, urine fertiliser has been in use in Uganda for more than a year.

"Applying diluted urine once every week for at least two months will more than double the yield of vegetables," says Patrick Makhosi, a soil scientist, in a story published online in ScienceDev. Imbuga agrees with the scientist in principle but says the claims must be verified.