What is RAW?

Readily available water (RAW) is the water that a plant can easily extract from the soil.

RAW is the soil moisture held between field capacity and a nominated refill point for unrestricted growth. In this range of soil moisture, plants are neither waterlogged or water-stressed.  Plant roots will continue to take water from the soil after the refill point is reached, but this water is not as readily available and the crop finds it difficult to extract. If the soil dries to the permanent wilting point, the plant can no longer remove any water from it: some water may still be present but is completely unavailable.
The drier the soil…. download the full article