Full Point
- The maximum water content of the soil that can be maintained against gravity without through-drainage or surface run-off.
- The wettest soil profile that can be regularly obtained after through-drainage has ceased.
- Like pulling a saturated sponge out of a bath of water - when the sponge stops dripping it is at the full point.
- Expressed as mm of water over a certain depth (e.g. 0-70cm).
- The VSW will not be constant down the soil profile.
- Dependant on soil type, but independent of the crop.
Finding the full point
- Take soil moisture readings when the soil is wet after heavy rain or after an irrigation.
- Identify the maximum rooting depth.
- This may not be possible because of roots deeper that measurements, or high water table.
- Look for the wettest profile at which there was no movement at 120cm.
- Any movements wetter than this profile at a depth below the root depth is a reading greater than then full point. Any wetter, and movement occurs at 120cm.
Readings wetter than the full point are showing as...
- Movements at 120 cm on the depth graph
- High ‘daily water use’ on the time graph
Case Studies: Motorgate |
ABC Blocks, Twaalfontein