Water plays many essential roles in plant growth and development, including transporting minerals and photosynthates. There are three forms of water in soil: gravitational water that leaches down, hygroscopic water tightly bound to soil particles, and capillary water available to plants. Capillary water fills micro pores in soil at field capacity after rain. Three forces - gravity, cohesion, and adhesion - are responsible for water movement in soil. Water is most available to plants at field capacity, with sufficient water and air in the soil. Cohesion, adhesion, salts, soil texture, and water potential all impact a soil's water availability to plants. Soils should be studied to effectively irrigate and make best use of water