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Upgrade from drip irrigation to measured irrigation

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Many smallholders use gravity feed drip irrigation to irrigate a small garden (less than an acre). The most commonly used scheduling method is programmed scheduling and this method wastes a lot of water because it does not respond to the prevailing weather conditions. By upgrading from programmed irrigation scheduling to measured irrigation scheduling, water usage may be reduced by 50% or more without affecting the yield The cost of the upgrade is negligible (the cost of a bucket and an adjustable dripper). Pressurised irrigation systems can also be upgraded.

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Measured irrigation evaporator

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The evaporator is any container with vertical sides with a suitable surface area of evaporation. Draw a level line on the inside of the evaporator about 1.5 cm below the overflow level. 

 

Position the evaporator in the garden, preferably exposed to full sun.

Position an irrigation dripper so that it will drip water into the evaporator. This dripper is called the control dripper and it should be at the same level as the other irrigation drippers in the garden.

 

The volume of water delivered by each dripper in your garden during an irrigation event is the same as the volume of water delivered to the evaporator by the control dripper.

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How to use the evaporator

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Check the water level in the evaporator at sunset each day.

If the water level is below the level line, start irrigating.

Stop irrigating when the water level reaches the level line.

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If the garden requires less frequent watering, you may choose not to irrigate on certain evenings. If the garden requires more frequent watering, you may choose to irrigate during the day as well as at sunset (for example if the weather is very hot and dry).

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You can also adjust the water usage rate to take account other factors in addition to the weather; for example, the soil type, the crop type, and the stage of growth. See Irrigation Scheduling for more details.