Why and how does water enter continuously into the root xylem?
Water is required by plants for photosynthesis. Transpiration is the process of water movement through a plant and its evaporation.
Transpiration pull makes the water enter continuously into the root xylem. The water is lost to atmosphere by the stomata. This water is pulled from the xylem to the roots to the leaves.
Cells of roots are in close contact with soil thus effectively take up particles by dispersion. The ion-concentration increments inside the root and henceforth osmotic pressure expands the development of water from soil into root which happens constantly.