Potential envergy of soil water due to the attractive forces (adhesion and cohesion) between water and the soil matrix. Matric potential is expressed as energy per unit volume and equals the product of the height of rise in a capillary tube, hm, the water density, ρ, and the gravitational constant, g, (ρghm). Matric head is expressed as energy per weight and is equal to the height of rise ina capillary tube (hm).