ICRISAT News – Feb 2019

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;
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• Household incomes improved, ranging from 21%-83%;
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• 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;
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• 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.
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• Reduced conflict between farmers and within households; and
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• 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).

Figure: 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.

See more https://www.icrisat.org/new-methods-in-implementing-an-irrigation-scheme-bring-notable-impact/