Potential for Reuse of Human Urine in Peri-urban Farming

Abstract

The possibility of recycling human urine for maize and vegetable growing was assessed on-farm in a peri-urban Kyanja parish, Kampala District, Uganda. The objectives were to demonstrate to farmers and other stakeholders, the potential for using urine and develop guidelines for use of urine in farming. Field plots measuring 1.5 × 6 m were established on 20 farmers’ fields and planted with maize (Zea mays L.), nakati (Solanum aethiopicum), kale (Brassica oleracea L.) and spinach (Spinacia oleracea L.). Urine was applied at 10% (0.5:5 urine to water), 20 and 30%. Each concentration was applied weekly, bi-weekly and monthly. Urine:water mixtures (20 L) were applied to each bed while the control received water only. Urine application significantly increased maize height and fresh yield; 30% urine weekly application gave highest benefits. Weekly application of 10% urine increased nakati yield from 8.3 to 22.2 kg/plot, within 2 months and yielded nearly the same biomass as that treated to 20% urine weekly. Weekly application of 20% urine increased the yield of kale from 2.4 to 5.5 kg/plot, and spinach from 6.6 to 17.1 kg/plot within 2 months. These represented the highest, most economical biomass yields compared to other treatments. Weekly application outperformed bi-weekly and least on once a month. From these findings, we propose the following guidelines: maize, apply 30% urine weekly for 8 weeks; nakati, apply 10% urine weekly for 8 weeks; kale, apply 20% urine weekly; spinach, apply 20% urine weekly. Since kale and spinach can grow for about 1 year, prolong urine application for continued harvesting.