By Katrin Glatzel
In sub-Saharan Africa (SSA) where agriculture is predominantly rainfed, farmers’ access to water is often limited based on seasonal variation. Yet water scarcity in the region is not necessarily caused by a physical lack of water, but rather by an ‘economic water scarcity’. This implies that the necessary public investments in water resources and infrastructure are not substantial enough to meet water demands in an area where people do not have the means to make use of water sources on their own. In fact, in many parts of SSA there is plenty of water available. However, groundwater resources, such as aquifers, remain a relatively abundant yet underused resource, with less than 5% of the water used for irrigation coming from groundwater.
The challenge is therefore to increase the amount of available water that is ‘harvested’ for crop growth. Such water harvesting can be done at the field, farm or watershed level. In some places, there is a potential for groundwater extraction using boreholes. And research by the International Food Policy Research Institute (IFPRI) has shown that motor pumps have the potential to expand the amount of agricultural land irrigated during the dry season to 30 million hectares — four times the current area. There is urgent need to sustainably increase the amount of irrigation from the current 6% of arable land. Until then an estimated 200 million people in SSA – that is 18% of the continent’s population – face serious water shortages.
Furthermore, climate change and a growing population continue to pose additional challenges to water management in agriculture. Prolonged periods of drought in many parts of SSA are becoming increasingly frequent. This increases pressures on valuable water resources and agricultural irrigation. In response, water conservation policies, strategies, and activities such as water harvesting, are ever more important to manage and protect fresh water as a sustainable resource to meet current and future human demands.
Sustainable Intensification of water management
At the same time, the challenge of meeting global food demand requires an increase in the level of agricultural water productivity and some increases in global water use. Finding ways of saving water or using ‘less drop per crop’ must therefore become a mainstay of agricultural production. Suitable water conservation methods minimise negative environmental impacts of drought such as soil erosion and desertification, whilst increasing crop yields throughout the year. Soil nutrients will only be used efficiently if a crop has sufficient water and water conservation can increase the volume of water available, bridging seasonal rainfall variability.
Water conservation contributes to Sustainable Intensification by allowing water to be used efficiently, resulting in higher agricultural production throughout the year and improved resilience to drought, improving farmers’ livelihoods and food security.
One example is water harvesting, which involves gathering water from a ‘catchment area’ and channelling it to the required area in a field. Some techniques can also work at a smaller scale to conserve water within the cropped area by reducing run-off and keeping the water where it falls as much as possible.
Four different methods highlight a spectrum of approaches currently available to farmers:
- Contour harvesting: Ploughing and furrowing, then planting along the ridges or contours rather than up and down the slope conserves water by reducing surface run-off and encouraging filtration of water into the crop area.
- Earth basins:Square or diamond shaped basins with earth ridges on all sides, earth basins can be constructed on any gradient and whilst most suitable for growing trees, they may also be used for other crops.
- Planting pits:Easy to construct small pits in which individual or small groups of plants are sown. The pits catch rainwater run-off and concentrate soil moisture around the roots.
- Drip irrigation:Drip irrigation carries water to fields through a system of plastic tubes where the water is slowly dripped onto the soil through small perforations in the tube. A small petrol pump can be used to push the water along the tubes for larger areas, but this will add a fuel cost and will need servicing.
Good governance and investments are key
Developing sustainable supplies of good quality water will be essential for working towards a thriving agriculture sector. To achieve this, increased public and private investments are needed to provide the technologies that enhance farmers’ capacity to adapt to climate change and increase their long-term resilience. This includes investments in mechanisation, irrigation systems, water catchment and conservation practices, but also in programs such as the African Agricultural Technology Foundation’s (AATF) water-efficient maize for Africa (WEMA) partnership and digital technologies. But it also requires a well-functioning enabling environment with a long-term vision that improves farmers’ rights to land and water, SSA will be well placed to end poverty and hunger and achieve long-term food and nutrition security while laying the foundations for sustainable agricultural growth.