Soil Water Storage (SWS)
Index Name: Soil Water Storage (SWS)
Ease of use: Red
Origins: Unknown – producers have been trying to measure soil moisture accurately since the beginning of agriculture.
Characteristics: Identifies the amount of available moisture within a plant’s root zone, which depends upon the type of plant and the type of soil. Precipitation and irrigation both affect the results.
Input parameters: Rooting depth, available water storage capacity of the soil type and maximum soil water deficit.
Applications: Used mainly for monitoring drought in agricultural contexts, but can also be a component in drought conditions affecting water availability.
Strengths: Calculations are well known and simple to follow, even using defaults. Many soils and crops have been analysed using this method.
Weaknesses: In areas where the soils are not homogeneous, there may be large changes in small distances.
Resources: Calculations and examples are provided in the reference below.
References: British Columbia Ministry of Agriculture, 2015: Soil Water Storage Capacity and Available Soil Moisture. Water Conservation Fact Sheet, http://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/agriculture-and-seafood/agricultural-land-and-environment/soil-nutrients/600-series/619000-1_soil_water_storage_capacity.pdf.