New methods in implementing an irrigation scheme bring notable impact

Efficient water use, higher crop yields and improved farmer incomes

Impacts of huge investments in irrigation schemes in Africa are often not realized. However, a series of ingenious irrigation schemes in Mozambique, Tanzania and Zimbabwe have shown multiple impacts including lesser water use, reduced conflict, higher crop yields and improved on- and off-farm household incomes. This was the outcome of over five years of work with two innovative tools for soil moisture and solute monitoring (Chameleon and FullStop Wetting Front Detector respectively). These were used along with a social process through Agricultural Innovation Platforms (AIPs).

Research on this component of the project showed the following impacts:

• Yield increase of the main crop was more than 25% for more than 60% of the households;
• Household incomes improved, ranging from 21%-83%;
• Water use decreased as the frequency of irrigation events were reduced in more than 50% of the households. Interval between irrigation events increased by 1.4 to 9 days;
• Improved off-farm income was reported by nearly 50% households with income sources changing from 11% to 66%. There is more spending on farming inputs, food and the home.
• Reduced conflict between farmers and within households; and
• Farmers’ knowledge increased with the usage of tools. They learnt about the complexities of movement of water and nutrients through the soil profile (see pic below).

Agricultural Innovation Platforms bring local expertise and knowledge together to develop and implement local solutions to scheme constraints. Photo: Martin Moyo, ICRISAT

A farmer connects a Chameleon reader to soil moisture sensors buried in his plot. Photo: Andre van Rooyen, ICRISAT

“Many farmers remain trapped in poverty due to low crop productivity, weak institutional arrangements and water governance, weak market integration and, in some cases, even abandonment of irrigated lands,” said Dr Anthony Whitbread, Research Program Director, Innovation Systems for the Drylands. “This is why these impacts we have are significant.”

Why the tools were introduced

The twin questions of “when and how much to irrigate” are critical to the success of irrigated agriculture. “The Chameleon and FullStop Wetting Front Detector (WFD) are two of a suite of tools introduced to build literacy around soil water and solute monitoring among researchers, extension workers and farmers,” says ICRISAT scientist Dr Martin Moyo.

What the FullStop WFD does

It is a funnel-shaped device buried in the soil with an indicator above the soil surface. It is used for –

• Monitoring nutrient losses in soils;
• Measuring how deeply water has penetrated into the soil after irrigation; and
• ‘Seeing’ what is happening in the root zone when the soil is irrigated.

What the Chameleon soil water sensor does

It was developed as a complimentary tool to the WFD to measure soil moisture. It consists of three or four sensors that are permanently installed at different depths in the soil. A portable handheld reader is connected to each group of sensors and displays the soil moisture as colored lights.

Learning from the water monitoring tools

The tools helped farmers to learn the following –

• Understand the complexities of the movement of water and nutrients through the soil profile;
• Correctly interpret the Chameleon colors and take necessary action. For example, reducing irrigation frequency and duration when blue is recorded at all depths.

FullStop Wetting Front Detector.

The road from learning to positive outcomes.

How AIP leveraged the learnings

The AIP served as a catalyst, bringing farmers and related stakeholders in irrigation together into an informal network to develop their capacity to solve problems and/or innovate. Farmers could meet with input suppliers, crop buyers, extension officers and government officials. Together they were able to have an in-depth look at the constraints and opportunities and developed a set of actions to work towards a collective vision for individual schemes.

The AIP-initiated activities have been diverse. Farmers have visited other irrigation schemes, which have inspired them to try out new, high-value crops such as groundnut and take up vegetable farming, especially garlic.

The above diagram shows the process of how learnings from the water monitoring tools lead to positive outcomes.

These findings are from work funded since 2013 by the Australian Centre for International Agricultural Research (ACIAR) and the CGIAR Research Program on Water, Land and Ecosystems (WLE). The scientific findings of this study are being featured in a forthcoming special issue of the International Journal of Water Resources Development.

A second phase of this work focuses on how best to scale out these findings through the project “Transforming smallholder irrigation into profitable and self-sustaining systems in Southern Africa”.

This work contributes to UN Sustainable Development Goal.