Water available for plants within the soil is

Soil water exists in multiple states, but not all forms can be absorbed by roots. Capillary water is held within the liquid phase inside small pores (micro-pores) between soil particles against the downward pull of gravity. It is the only significant source of water that is readily available for absorption by plant roots.
Hygroscopic water* forms an ultra-thin film tightly held around soil particles and cannot be extracted.
Chemically bound water* forms part of the crystalline structure of soil minerals.