Evaluation of human urine as a source of nutrients for selected vegetables and maize under tunnel house conditions in the Eastern Cape, South Africa

Abstract

The introduction of ecological sanitation (ECOSAN) toilets in South Africa has created opportunities for safer sanitation and recycling of human excreta, as fertilizers, in rural and peri-urban areas. A study was carried out to evaluate the fertilizer value of human urine (0 to 400 kg N ha(-1)) for maize and tomato, compared to urea, in a tunnel house. Dry matter yield of both maize and tomato, harvested at 9 and 10 weeks after planting, respectively, increased with increasing N rate (both as urine or urea) up to 200 kg N ha(-1). Urea reduced soil electrical conductivity (EC) whereas urine increased it. Leaf tissue Na, in both crops, also increased with urine application. A follow-up study was carried out with two crops with contrasting sensitivity to salinity and using a wider range of N application (0 to 800 kg N ha(-1)). The results indicated increased root and leaf dry-matter yield of beetroot (tolerant to salinity) with increased urine rates up to the highest rate of 800 kg N ha(-1), whereas the leaf and root dry-matter yield of carrot, which is sensitive to salinity, peaked at the low urine application rate of 50 kg N ha(-1). Soil EC increased with urine application up to 4.64 and 13.35 mS cm(-1), under beetroot and carrot, respectively. Generally the results showed that human urine compared well with urea as a source of N for crops but optimum rates depend on the sensitivity of the crops to soil salinity, which should be monitored where human urine is regularly used for fertilizing crops.

Producción de plántulas de chile jalapeño fertilizadas con orina

“…However, potassium and phosphorus content in the substrate was higher when Steiner solution was applied. It is likely that some nutrients contained in urine were absorbed by seedlings or accumulated in the substrate at different rates than Steiner solution, which coincides with that reported by Jönsson et al (2004), and Mnkeni et al (2008).…”

“…Sin embargo la aplicación de orina diluida a una CE de 1 dS m -1 causo los mismos efectos en todos los parámetros de crecimiento que la solución Steiner. La orina ha sido recientemente evaluada como un fertilizante alternativo Pradhan et al, 2007;Mnkeni et al, 2008); sin embargo, su aplicación directa ha causado efectos negativos en plantas y suelo atribuidos a la alta salinidad de este residuo (Beler-Baykal y Bayram, 2007;Beler-Baykal et al, 2011), lo cual indica que es requerido diluir la orina previamente a su aplicación como fuente nutritiva orgánica en sistemas productivos agrícolas.…”

“…However, the application of diluted urine at EC of 1 dS m -1 caused the same effects in all growth parameters than Steiner solution. Urine has recently been evaluated as an alternative fertilizer Pradhan et al, 2007;Mnkeni et al, 2008); however, direct application has caused negative effects on plants and soil, attributed to the high salinity of this residue (Beler-Baykal and Bayram, 2007;Beler-Baykal et al, 2011), indicating that is required to dilute urine prior to their use as organic nutrient source in agricultural production systems.…”

“…Con respecto al alto contenido salino en la orina, existe evidencia que la aplicación directa de orina no diluida incrementa el contenido de salinidad en suelos (BelerBaykal et al, 2011), lo cual afecta el desarrollo de las plantas desde las plántulas hasta las etapas maduras de producción y reproducción, particularmente en cultivos sensitivos a salinidad (Mnkeni et al, 2008). Dos de los tratamientos recomendados para reducir los efectos negativos de la alta salinidad de la orina son el ajuste del pH mediante adición de ácidos, así como la dilución de la orina para reducir su salinidad (Capulín et al, 2005;García et al, 2008;Preciado-Rangel et al, 2011).…”

“…Regarding high salt content in urine, there is evidence that direct application of undiluted urine increases soil salinity content (Beler-Baykal et al, 2011), which affects the development of plants from seedling to mature stages of production and reproduction, particularly in crops sensitive to salinity (Mnkeni et al, 2008). Two recommended treatments to reduce negative effects of high salinity in urine are pH adjustment by addition of acids and the dilution of the urine to reduce its salinity (Capulín et al, 2005;Garcia et al, 2008;Preciado-Rangel et al, 2011).…”