Gamma-ray soil mapping is a highly repeatable technique with good spatial consistency, but accuracy depends on several factors:
- Calibration – Sensors are factory-calibrated and can be recalibrated against reference pads or soil samples for enhanced accuracy in specific regions.
- Soil sample correlation – Accuracy improves significantly when gamma-ray data is combined with a set of reference soil samples from the survey area.
- Survey design – Line spacing, survey speed, and sensor height all affect spatial resolution and data density.
- Environmental conditions – Heavy rain shortly before a survey can temporarily affect signal strength due to radon washout.
In peer-reviewed agricultural studies, gamma-ray mapping has achieved R² values above 0.85 for clay content prediction when combined with soil calibration data. For qualitative soil zone delineation, the technique is highly reliable even without calibration.