2025-26 season off to a high irrigation demand

We are all aware that the past few weeks (7 to be precise) have been hotter and windier than normal. As such the irrigation demand has increased significantly. This on top of a dry end to winter and dry start to spring. The increase in irrigation demand is clearly indicated in the total weekly ETo’s when comparing this season to the past 11 years (graph below with this season’s data in red). This data was taken from a client in the Warmbokkeveld’s (Western Cape, South Africa) weather station. As such it is a point location but clearly demonstrates the trend that we have all be perceiving.

What does this mean for irrigation?

We are in the critical period for fruit growth in most crop types. As such, we need optimal soil moisture throughout the whole soil profile. Longer irrigations to fill up the subsoil at 60-80cm is critical, and due to the higher water demand (ETo) more frequent irrigations may be required. However, do not over-compensate and saturate soils.

Monitor your probes and physical soil moisture evaluations carefully. Probes must remain in the “green zones” for both the root zone and buffer zone. Physical soil moisture evaluations need to remain a 3 to 3+ through the profile. During this time of the season when there is rapid fruit enlargement is not when one cuts water to save.

Additional graphs below show that the maximum and minimum weekly temperatures are higher than the previous 10 years. The relative humidity has been lower than average, as well as the drier start to the season with lower rainfall. Solar radiation is a large driver in the ETo calculations, however the graphs indicate a fairly average trend compared to previous seasons. Thus, the higher temperatures, lower humidity and more consistent wind is the cause for the higher water demand in the orchards.

Follow up on soil moisture in all blocks to ensure optimal soil moisture is maintained.

When in doubt, dig a hole!