We know that there is no one-size-fits-all answer to improved irrigation scheduling on macadamias or any other crop. As we aspire toward increased efficiency, various aspects must be kept in mind. When we want to manage water optimally in orchards it is important that we understand water balance in an orchard, soil-water interaction and factors that impact it.

Efficient water use is about preventing water loss on the one hand and ensuring optimal water intake by the roots on the other hand. Water loss can occur through evaporation, deep percolation, subsurface outflow, run-off and transpiration.

The latter is the only positive water loss as water moves through the plant. Our aim is, therefore, to maximise tree transpiration while we minimise soil evaporation and water use by vegetation between tree rows.

The main concern is evaporation and deep percolation. LImiting these two culprits is key, as they can then ensure highly efficient water use. Evaporation is limited by wetting a smaller soil area and deep percolation is limited with proper irrigation scheduling through which we can ensure we do not irrigate beyond the active root zone.