Soil probes pull back the covers

Soil probes are providing an almond farm in Stellenbosch with an intimate look beneath the surface, revealing how smart irrigation and cover crops can optimise orchard performance.

- Robyn Joubert

At Knorhoek Almond Farm in Stellenbosch, farm manager Francois Vermeulen and his team are lifting the covers.

For years, the true state of the four-year-old orchard’s root zone remained hidden from view.

Yet the introduction of continuous soil moisture probes in 2023 has allowed the team to look beneath the surface and see exactly what's happening down there.

The insight is driving a data-driven approach to orchard management where precision irrigation and cover crops are proving to be effective partners working together to create the ideal environment for the root zone and building long-term orchard resilience.

THE MORE CLEARLY WE CAN SEE BELOW THE SURFACE, THE BETTER DECISIONS WE CAN MAKE

The impact has been transformative. While the irrigation norm for almonds is estimated at between 8 000m³ and 11 000m³ per hectare per season, the Knorhoek team used an average of only 4 000m³ for trees in full production and around 2 000m³ for the younger trees.

The need for closer monitoring became apparent when one 2,3ha block of the 3,9ha orchard remained consistently wetter than the rest.

“The entire orchard block operated on a single irrigation system, making it difficult to manage varying soil conditions across different sections,” says Jeromeo Mento, horticulturist at DFM Technologies.

To diagnose what was happening beneath the surface, Vermeulen installed 80cm probes from DFM Technologies at a rate of one probe/ha or one probe per irrigation block. The probes provide continuous, real-time readings of soil moisture and temperature at multiple depths throughout the root zone, in some cases down to 1,8m.

The probe data allows Vermeulen to track how water moves through the profile, how roots respond to irrigation, and how environmental conditions affect root activity over time.