Soil moisture is the amount of water present in the soil.
- Gravimetric: the mass of water/mass of solid material
- Volumetric: the volume of soil/total porosity
The amount of void space within a soil depends on the distribution of particle sizes, and is quantified by soil porosity.
Soil moisture is more generally considered within the context of hydrology, where it represents the immediate store of infiltrating rainfall, before it either evapotranspires or contributes to groundwater recharge.