Volumetric Water Content (VWC): A numerical measure of soil moisture. It is the ratio of the volume of water to the unit volume of soil. It is expressed as a percentage.
Our capacitive dielectric sensors monitor VWC directly at the root zone. By knowing the precise VWC, farmers avoid triggering irrigation pumps blindly, saving up to 40% on annual water and electricity costs.
Volumetric water content (VWC) is the volume of water per volume of soil, expressed as a percentage. A VWC of 30% means 30% of the soil's volume is water. Two reference points matter: field capacity (the water soil holds after gravity drainage, typically 20-40% depending on texture) and permanent wilting point (the level below which roots cannot extract water, roughly 5-15%). The band between them is plant-available water.
Raw VWC numbers mean little without soil-texture context — 25% VWC is comfortably moist sand but drought-stressed clay. That is why moisture sensing must be calibrated per field, and why a single reading depth is not enough: crops draw from different depths as roots develop through the season.
VK-Series nodes read capacitive VWC probes at multiple depths every 15 minutes. The gateway learns each field's drainage curve and flags both stress (approaching wilting point) and waste (drainage past field capacity), turning a raw percentage into an actionable irrigation window.
It depends on soil texture. Most crops thrive when VWC sits between roughly 50% and 80% of the soil's plant-available water band — for a loam with field capacity of 34% and wilting point of 12%, that means keeping VWC around 23-30%. Crop guides on this site list per-crop target bands.
Capacitive sensors measure the soil's dielectric permittivity, which rises steeply with water content because water's dielectric constant (~80) dwarfs dry soil's (~4). The electronics convert that permittivity to a calibrated VWC percentage.
See also: Capacitive Soil Sensor, Evapotranspiration — or browse the full smart farming glossary.
Discover how VarshaKrishi utilizes this technology in our offline-first systems across rural India.
Read our Ultimate Guide to Smart Farming