Contents
How Many Probes to Install
The right number mainly depends on field heterogeneity. The more your soil, topography, or irrigation varies, the more measurement points you need.
Related guides
Baseline rule
- Uniform field: start with 1 measurement point.
- Heterogeneous field: move to 1 point per homogeneous zone.
- Fine control objective: add points in high-stakes zones (recurring stress, edges, unstable areas).
When to increase the number of points
- When soil textures change (sandy/silty/clayey).
- When slope, low points, or exposure create different water behavior.
- When multiple irrigation systems or sectors are used.
- When irrigation decisions based on one point no longer match what you observe in the field.
Measurement depths
The number of horizontal points (how many probes) and the number of depths (vertical reading) are complementary:
- For shallow-rooted crops, a short profile can be enough.
- For deep-rooted crops, monitoring multiple layers is recommended to verify lower-profile wetting.
- Multi-depth probes often reduce the need for many horizontal points while keeping a strong vertical view.
Decision support table
| Situation | Recommended number |
|---|---|
| Uniform field, one crop, one irrigation setup | 1 point |
| Heterogeneous field | 1 point per homogeneous zone |
| Different irrigation sectors | 1 point per key sector |
| High water-risk crop / high variability | 2+ points based on critical zones |
What we recommend
Start simple with 1 point per homogeneous zone, then adjust using observed differences between zones. To define exactly where to install each probe, use our dedicated guide: Where to Position Probes.
Frequently asked questions
Should I use one probe per field or several?
In a uniform field, 1 point can be enough to start. If the field is heterogeneous (soil, topography, crop, irrigation), instrumenting each homogeneous zone is usually better.
Should I also increase measurement depths?
Yes, especially for deep-rooted crops. Monitoring multiple depths in one profile helps verify water penetration and reduce leaching risk.
Where should probes be placed once the number is defined?
Use our dedicated placement guide: Where to Position Probes.