Soil Moisture
Soil moisture is a measurement of water content, or water availability. Soil water content typically ranges between 0.05 and 0.40 g/g (θm gravimetric).
θm = gravimetric water content = mass of water per unit mass of dry soil (g/g; kg/kg etc.);
θv = volumetric water content = volume of water per unit volume of soil; (cm3/cm3; m3/m3).
The fertility of a soil is determined by how many kinds and how much nutrients it has stored and is able to supply. Nitrogen (N) mostly in the form of nitrate (NO3-) or ammonium (NH4+), phosphorus (P in the form of H2PO4- or HPO4-), and potassium (K as K+) are three often mentioned soil nutrients important for the growth of plants.
