The food supply in many parts of sub-Saharan Africa is considered insecure in terms of national figures of calories per person. Most communities rely on rain-fed agriculture but crops are prone to poor yields with erratic rainfall, which is affected by climate change. The EU has recognised links between poverty, development and the environment and aims to integrate policy in this areas1.
Promoting irrigation can reduce poverty, increase food security and help adaptation to climate change. Currently drip (or micro) irrigation is rapidly expanding in sub-Saharan Africa. Drip irrigation delivers water directly to the roots of plants which increases soil moisture. Photovoltaic (or solar) powered drip irrigation (PVDI) combines the efficiency of drip irrigation with the reliability of water pumps powered by the sun. The system uses no batteries and is self-regulating, i.e. since the sun drives both the pump speed and evaporation from plants, the volume of water pumped increases on clear hot days when plants need more water.
The research compared two villages that had installed PVDI systems with two similar villages that watered their plots by hand. The results indicated that the PVDI systems supplied, on average, 1.9 tonnes of produce per month. Villages without PVDI appeared to produce much less, even during the rainy season, although the researchers were unable to measure exactly how much due to food being grown in scattered home gardens. Access to food from both home production and purchasing increased dramatically for families of farmers using PVDI. The number of PVDI households under the poverty line remained the same after installation, but for the villages without PVDI there was an increase in those under the poverty line.
Consumption of vegetables increased in the villages with PVDI compared to those without. During the rainy season vegetable intake increased in all villages by 150g per person per day (approximately one serving) compared to the previous year. During the dry season the vegetable consumption in villages with PVDI was higher than villages without PVDI by about 500-750g per person per day (approximately 3-5 servings). The study noted that there was no 'surplus production' meaning that the area could support more PVDI systems without saturating demand.
The research investigated the economic and environmental sustainability of PVDI. Although PVDI has a higher up-front cost than irrigation systems using liquid fuel pumps, the access to capital would be better if adopted by a group. With an increased demand and improved supply, PVDI costs could be driven down. The environmental sustainability will depend upon year-round access to water, but due to their emission-free status the research calculated that a garden using PVDI would save 0.86 tonnes of carbon emissions per year compared to a liquid-fuel alternative.
The study indicated that PVDI has economic, nutritional and environmental benefits. However, PVDI requires significant learning for users to be managed effectively. Access to technical support and long-term involvement needs to be provided by those that implement the projects to ensure sustainability.
Source: Burney, J., Woltering, L., Burke, M. et al. (2010). Solar-powered drip irrigation enhances food security in the Sudano-Sahel. Proceedings of the National Academy of Sciences. 107(5):1848-1853.