SATI Beyond The Bunch 1st Quarter 2026

A case study of variability

the shallow soils extended only to 30 cm below the surface, whereas those in the deeper soils extended to 80 cm. All blocks were irrigated three times per week, but the shallow soils dried out within a day. Chronic moisture stress was stunting the vines in the shallow areas. Switching to shorter, more frequent irrigations alle viated the water stress in the weak vines without stimulating additional vigour in the vines with deep root systems. Follow-up NDVI images (Figure 2) and visual assessments demonstrated significantly improved uniformity within two seasons.

Satellite images of a commercial table-grape farm in Robertson highlighted non-uniform vigour, as evidenced by highly variable NDVI (normalised difference vegetation index) within most blocks (Figure 1). Visual observations in the vineyards confirmed this. Although the situation seemed to call for differential nitrogen application and vine manipulation, these practices wouldn’t have solved the problem. The issue was irrigation, not nutrition, with variable soil depth as the root cause of variable vigour. The non-uniform vineyards had a patchwork of shallow and deeper soils. The root systems of vines in

VIGOUR

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Average

High Cloud Cover

FIGURE 1. The NDVI map of the vineyards in January 2024 shows highly variable vigour. Image taken from the IMPI platform and supplied by AgriMotion.

FIGURE 2. The NDVI map of the vineyards in January 2026 shows a significant improvement in uniformity. Image taken from the IMPI platform and supplied by AgriMotion.

BEYOND THE BUNCH • 5 • QUARTER 1 • 2026