/Persistent irrigation woes weaken agricultural development

Persistent irrigation woes weaken agricultural development

Small-scale irrigation has been lauded as the key to building climate resilience by changing Zimbabwean governments, yet it has often failed in the past. The reasons are plentiful, but low crop yields and under-performing agricultural markets carry part of the blame. When farmers either have very few crops to sell—or no one to sell crops to—they have little funds and incentive to invest in irrigation.

Another reason is poor water management. For example, water is not always shared fairly: some farmers, with plots located close to the water supply, may receive much more water than farmers with plots further away. Because water delivery and distribution is not predictable, farmers tend to over-water their crops, causing water scarcity, nutrient losses, waterlogging, land degradation and soil salinization.

During the past five years, I have been working with colleagues from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and the CGIAR Research Program on Water, Land and Ecosystems (WLE) to solve these and other, interlinked challenges.

What’s new: technology and learning make a winning pair
First, we have introduced two easy-to-use tools that help farmers to apply just the right amount of water to their crops. One is a so-called wetting front detector: a small device buried in the soil with an indicator above the surface that shows how deep into the soil water has infiltrated, thus giving a good sense of whether more irrigation is needed. Farmers can also extract water samples from the device and use those to measure the soil’s nitrate and salinity status, helping to reveal if over-watering is leaching out nutrients.

The second device, called the Chameleon, complements the wetting front detector, and consists of three or four sensors permanently installed at different depths in the soil. A hand-held reader shows blue light for wet soil, green light for moist soil or red light for dry soil. In combination, the two tools make it much easier for farmers to know whether their crops need more water.

But technology alone is not enough. We introduced these two tools within the context of agricultural innovation platforms—informal institutions that bring together farmers, government officials, traders, researchers and others. As these different types of people had the opportunity to share knowledge, new ideas about how to use these tools and improve the system as a whole emerged. We found for example that farmers learned from each other and were able to get market information that led them to grow new, higher-value crops.
Andre van Rooyen/ICRISAT.