Converting Readily Available Water to litres for drip irrigation

Page last updated: Friday, 28 August 2020 - 2:36pm

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Drip irrigation is common in modern orchards. For this method of irrigation it is easier to use litres rather than the more traditional unit of millimetres when describing readily available water in the plant root zone. Using litres also allows simple calculation of irrigation time.

Several factors need to be considered when considering readily available water and drip irrigation and are explained.


Where irrigation water and plant roots are evenly distributed over the whole planting area, water storage and plant water use can be measured in millimetres. Drip irrigation distributes water over a small part of the whole block and roots follow this water distribution. In these cases, it is often easier to use litres to describe both water use and storage in the plant root zone.

This also allows simple calculation of irrigation time as the discharge from drip systems is commonly reported in litres per hour.

Rule to remember

1mm depth of water = 1L applied to 1 square metre.