Soil moisture index

  Assessing the amount of water available in a soil, as compared to its optimal reserve (useful reserve). When the soil moisture index (SWI) is close to 1, the soil is wet (greater than 1, the SWI indicates that the soil tends to saturation). Conversely, when it tends to 0, the soil is under water stress (less than 0, it indicates that the soil is very dry).