The Robotic Divining Rod: UC Riverside Unveils Tree-by-Tree Soil Moisture Mapping to Combat California Drought

UC Riverside researchers unveil a robot that maps soil moisture tree-by-tree. Learn how electrical conductivity is used to save water and prevent fertilizer runoff.

By: AXL Media

Published: Apr 2, 2026, 11:31 AM EDT

Source: The information in this article was sourced from EurekAlert

Beyond the Buried Sensor: A New Era of Precision

In the face of intensifying drought and tightening groundwater regulations, California growers are searching for ways to maximize "crop per drop." Traditionally, farmers have relied on soil moisture sensors buried at fixed locations. While helpful, these sensors are expensive and only provide a "snapshot" of the immediate area. Because soil texture—ranging from water-retaining clay to fast-draining sand—can vary significantly within a single orchard, neighboring trees often experience vastly different conditions despite receiving the same amount of water.

The Science of Conductivity

A research group led by Elia Scudiero, Associate Professor of Precision Agriculture at UC Riverside, has bridged this data gap using a mobile robotic system. Detailed in the journal Computers and Electronics in Agriculture, the system utilizes a robot that traverses orchards to measure electrical conductivity. This property indicates how easily electricity moves through the soil, which is heavily influenced by moisture, salt, and clay content. By pairing these mobile readings with data from existing buried sensors, the team created a statistical model that predicts water content across the entire field with tree-by-tree accuracy.

Finding the "Sweet Spot" for Plant Health

Maintaining the correct moisture level is a delicate balancing act. Under-watering leads to stressed trees that are susceptible to pests, while over-watering fills soil pores with water instead of oxygen, effectively "suffocating" the roots. "There’s a sweet spot," Scudiero explains. The robotic mapping system allows growers to identify exactly which trees need water, preventing the waste of a becoming-scarce resource while ensuring every tree remains in that ideal health zone.