Irrigation Practices in West Africa

Tomatoes grow best in dry, arid environment; they do not like humidity or rain, which can cause bruising and mold growth on the fruits. However, with a water content of up to 95%, tomatoes actually require a lot of water to grow. Most of the farmers we met in West Africa prefer to farm tomatoes during the dry season when rainfall is unlikely. So where does all the water required to make the tomato plump and juicy come from?

During our field visits in Ghana and Nigeria, we observed two main categories of irrigation: flood/surface irrigation and sprinkler irrigation.

Flood irrigation is the most common technique practiced by the farmers we met in West Africa. Water is sourced from rivers, lakes, wells, boreholes, or public irrigation schemes, and is typically pumped into the field using a diesel generator and flexible hose. Some farmers own their own pumps – others share or rent. Once the water reaches the field, the farmer has to decide which technique of flood irrigation to use. The following methods are common:

·      Basin – A plot of land is leveled and surrounded by a border/ridge of compacted soil. This plot is then flooded with water leaving the crops to absorb the water over time. This method is most suitable for water loving crops like rice.


·      Furrow – The field is leveled and ridges and furrows built. These ridges act as natural irrigation channels. Farmers typically pump water to fill the furrows, allowing it to soak the fields until it drains or is evaporated. This technique is often used to grow vegetables and maize.

·      Bay or Border Strip – The field is leveled and ridged, but the ridges run parallel to the slope of the field. Water flows down a trough along the side of the ridges, and “gates” are opened in turn to allow the water to flow into each the channels.

These methods share a common characteristic: they are built in such a way that the main “trough” or feeder channel runs the length of the field, feeding the secondary channels. One major drawback to flood irrigation is that it uses water very inefficiently.  Most of the water either evaporates or ends up being absorbed by the soil rather than the plants.


Sprinkler irrigation solutions, though more expensive to set up, are much more efficient at delivering water to crops, enabling higher yields with lower water utilization.  We observed three methods of sprinkler irrigation in West Africa: 

·      Centre-Pivot  – This week we travelled to a newly commissioned centre-pivot scheme at the Gurara dam, near Abuja, Nigeria. A centre-pivot delivers water from overhead sprinkler hoses or nozzles that are attached to a mechanically rotating pivot, which sprays a large circular piece of land. The pivots in Gurara irrigated circular areas of land with an area of either 20 or 40 hectares.

·      Travelling Gun – The “traveling gun” sprinkler moves along a rail system that runs parallel to the crop rows. Water is sprayed down over the tops of the crops. This system is not ideal for tomatoes but is used to irrigate many other fruit and vegetable crops.

·      Drip – Drip irrigation considered to be the gold-standard irrigation method for tomato farming. The technology typically uses 50% less water and can improve yields by as much as 40%. It is a low pressure, low volume system designed to direct water to the base (and in some cases directly to the root) of the plant. The drip system is designed to maintain a constant soil moisture and high nutrient content. Unfortunately, drip irrigation schemes are expensive to install and maintain. Installation requires a careful study of the land topography, while maintenance requires careful filtering of the water so that particles do not clog the emitters.

This is where Tomato Jos comes in. The large upfront cost of installing drip irrigation is beyond the reach of the smallholder farmer who often struggles to pay for seeds and other basic inputs. We plan to offer our most advanced and reliable smallholder farmers the opportunity to farm with drip irrigation, so that farmers can experience the dramatic yield increase associated with this technology.