Volumetric Water Content (VWC) is the volume of water per unit volume of soil, expressed as a percentage of the volume. This number varies with the type of soil. Sandy soils have a lower number (usually in the teens) while heavier soils can approach 30%.
Field capacity (FC) is the amount of soil moisture or water content held in the soil after excess water has drained away and the rate of downward movement has decreased. This usually takes place 2–3 days after rain or irrigation in pervious soils of uniform structure and texture.