This Plant for Soil Moisture Monitoring is designed to help you keep an eye on the moisture levels in your soil. It features a built-in sensor that measures the moisture content in the soil and sends the data to your smartphone or tablet. The app then provides you with real
From Wikipedia
Soil moisture is the water content of the soil. It can be expressed in terms of volume or weight. Soil moisture measurement can be based on in situ probes or remote sensing methods.