This post is written by Jonathan Lautze and Manuel Magombeyi, IWMI. 

Improving food security and farm-based livelihoods is, bluntly put, among the central challenges of our time and key to fostering progress toward a set of Sustainable Development Goals such as reducing hunger and poverty. The primary pathway for enhancing food security and farming livelihoods – boosting agricultural production – is nonetheless constrained by limited and erratic water resources availability. Irrigation is critical to optimize the use of water in agricultural production, yet globally it constitutes the highest (>70 percent) water use and is already placing substantial pressure on natural water resources and flow patterns.

In the shared Tuli Karoo System (Botswana, South Africa, Zimbabwe), irrigation from both ground and surface water is key to the production of cereals, legumes, and vegetables as well as high value crops and livestock. However, constraints in water availability are very much real. In most years, water shortage results in farmers not fully cultivating all irrigable hectares in their schemes. To respond to this situation, one option is to look for additional sources of water, particularly based on an improved understanding of the shared aquifer. Another option, pursued in parallel, is to work towards improving irrigation efficiency so that the benefits of existing water resources can be stretched farther to achieve greater and more effective agricultural production.

To improve irrigation water use efficiency, innovative tools such as the Chameleon sensor and Wetting Front Detector (WFD) have been successfully tested in several environments in Africa. These tools allow farmers to understand, adjust, and optimally apply water to the soil and particularly the crop root zone. Evidence from the region points to potential water savings by about 40 percent, nutrient loss reduction by about 40 percent, and gross irrigation water productivity improvements by as much as 60 percent. In the Tuli Karoo System, such tools are being utilized in four irrigation schemes to improve crop yield, productivity, income, profitability, and food security through improved management of soil-moisture and nutrients, which together work to reduce poverty.

Zooming out from the Tuli Karoo, improving irrigation water use efficiency is essential for the sustainability of agriculture for farmers in Africa. Smallholders are especially important as they comprise more than 70 percent of farmers and contribute to the majority of food production. A particular advantage of the approach used in the Tuli Karoo is the capacity building through knowledge-sharing and co-learning. Farmers learn how the tools work, and co-learning with researchers allows farmers to adapt their irrigation scheduling to minimize excessive irrigation water application. The potential for broader application of such innovative tools in other geographies in Africa looks promising.

Acknowledgment: This work is being undertaken in the context of a USAID-funded project entitled Conjunctive Management of Transboundary Waters in the SADC Region: Generating Principles through fit-for-purpose practice.