SATI Beyond The Bunch 1st Quarter 2026

DEWALD KIRSTEN | LUCENTLANDS

LUCENTLANDS As mentioned above, weather stations are crucial to irrigation management. If there isn’t a weather station within 5 km of the farm, growers should consider installing their own. Several companies offer this service. If used to plan irrigation schedules, the service should include forecasts of evapotranspiration demand. Besides facilitating proactive irrigation, weather stations and evapotranspiration-demand estimates also help growers sense-check their water delivery. For example, if conditions have been cool and rainy and growers haven’t applied less water, but a probe indicates drier soils, there is a problem (with that probe or with water delivery in that area of the block). Remote sensing Remote sensing using drone- or satellite-mounted instruments has become a standard tool for measuring vigour in vineyards and orchards, with several companies offering mapping services. Satellite monitoring can provide updated data as often as every four days. Vigour is usually estimated based on NDVI. Remote sensing data must be calibrated using visual observations at least once, but preferably three times per season. Although vigour maps highlight spatial variability, figuring out the cause still requires boots (and usually a spade) in the vineyard. Technology is now also available to map fruit development and crop load within vineyards, for example, by analysing data from vehicle-mounted cameras. Although this is mostly a tool for harvest prediction, it delivers spatial information that can supplement vigour maps and provides clues to problem areas within a block. At the cutting edge, researchers are working on remote sensing utilising multispectral imaging, for example, to identify moisture stress in vineyards. Resources discussing some of these projects are listed under Further reading. Samples and spreaders Soil samples before vineyard establishment are indispensable. Thereafter, soil samples should be

repeated at least every three years, and more frequently when managing a soil problem such as salinisation. Leaf samples should be analysed annually. Both soil and leaf samples inform fertilisation pro grammes, so they need to reflect the vigour variability across the block. Soil and leaf samples are covered in detail in the 2025 Q2 issue of Beyond the Bunch. Variable fertiliser applications are one tool to manage variable plant needs. Spatial maps obtained from remote-sensing platforms are now routinely used to generate GPS maps for variable-rate spreaders, enabling precision nutrition in vineyards. In the near future, growers will likely also have access to GPS-enabled sprayers for precision application of foliar feeds, plant growth regulators, and even crop protectants. Natural and artificial intelligence Artificial intelligence and machine learning could expand growers’ toolkits for precision irrigation and nutrition. For example, artificial intelligence can theoretically integrate data from multiple sources, including soil moisture probes, stem water potential loggers, remote sensors, and weather stations, to estimate irrigation requirements. The same artificial intelligence could then determine the optimal irrigation schedule based on information about water availability, pump capacity, system delivery, and even electricity rates. Should conditions change (for example, a pipe bursts), the irrigation plan could be automatically updated. Such a system would have many advantages, not least freeing growers from daily scheduling decisions. But we’re not there yet. For now, growers’ best bet is to harness the natural intelligence of qualified irrigation and nutrition consultants who can help them map and prepare their soils, calibrate their soil moisture estimates and probes, make sense of the data deluge, and ultimately implement precise yet practical measures that optimise vineyard performance and profitability.

Acknowledgements The following specialists provided technical inputs:

• Eunice Avenant. Training manager at SATI and extraordinary lecturer in Viticulture in the Department of Viticulture and Oenology at Stellenbosch University. eunice@satgi.co.za. • Dr Carolyn Howell. Senior Researcher at the ARC Infruitec Nietvoorbij. howellc@arc.agric.za. • Danie Kritzinger. Soil scientist and horticulturist at AgriMotion. danie@agrimotion.net.

• Karen van der Westhuizen. Soil scientist and irrigation consultant at MuddyBoots. karen@muddyboots.co.za. • John-Murray Visser. Senior research assistant (soil physics and soil-plant interactions) in the Department of Soil Science at Stellenbosch University. visserj@sun.ac.za.

BEYOND THE BUNCH • 11 • QUARTER 1 • 2026