Capillary water: 
Water is held in a soil mixture by the action of surface tension attracting water molecules to soil particles. This is called capillary action. This counterbalancing force that keeps it from moving downward is surface tension, which causes the water to 'stick' to soil particles. The smaller the soil particles are, the more combined surface area they have, and the more they are able to hold onto water through its surface tension. Hence, for the growth of plants, the useful soil moisture is capillary water it can retain in the soil for a longer period.