A loaded tunnel varies in three directions. DMR fills to 2 to 2.2 metres, so the top of the mass and the layer near the floor differ, and the far end differs from the door end.
No Indian source publishes how many probes a tunnel needs. The count follows your geometry and the zones you know go wrong, so measure it on your farm rather than copy a number. Use the DMR rule that the spread must not exceed 3 °C to test whether your coverage is enough.
- Front and back
- Top, middle and bottom
- Zones with a bad history