Sensors in the Soil

A Compact Solar-Powered Soil Monitoring System for Smart Farming

- By Maheshwaran Sadasivam and Vairamani Kanagavel

Combining basic sensors and low-cost ESP32 processing builds a system that can make any farming operation smarter, no matter where it is.

Seven critical soil parameters-temperature, moisture, pH, electrical conductivity (EC), nitrogen (N), phosphorus (P), and potassium (K)-are essential for data-driven agricultural decision-making on any farm. We built a system around a 7-in-1 data sensor that collects data and transmits wirelessly to the Adafruit IO cloud platform, where it is displayed on a custom dashboard and archived for historical analysis. We then developed a mobile application using Flutter. It interfaces with the Adafruit IO API, enabling farmers to remotely monitor real-time soil conditions from anywhere.

The sensor package operates entirely on solar power using a rechargeable battery, making it self-sustaining and ideal for off-grid agricultural fields. While the prototype demonstrates a single-node configuration, the system is inherently scalable.

Multiple such nodes can be deployed across a farm to digitize soil conditions, offering localized insights that enhance irrigation efficiency, nutrient management, and crop yield optimization.

We installed the device in an agricultural field, and its measurement data was updated to a Flutter mobile application shown in Figure 1. The soil parameters were updated on the Adafruit IO dashboard. as shown in Figure 2.

A SOLAR-POWERED SYSTEM

As shown in Figure 3, the system consists of a 2W solar panel, with a circuit to charge and manage the 3.7V 2,500mAh battery. A boost converter module is used to boost the 3.7V to 5V, and its output is used to power the ESP32, RS-485 to UART converter and 7-in-1 soil sensor.