Field Validated Hybrid ESP-NOW and Long Range IoT Monitoring System for Energy Autonomous Precision Agriculture

Agriculture in arid and semi-arid regions faces critical challenges of water scarcity, irregular rainfall, and the high cost of monitoring systems. Most existing Internet of Things (IoT) platforms for precision agriculture are expensive, energy-intensive, and rely on cellular or grid connectivity, which limits their adoption by smallholder farmers. To overcome these issues, this work presents a hybrid Espressif peer-to-peer protocol (ESP-NOW) / long range (LoRa) IoT monitoring system. The architecture combines ESP8266 sensor nodes, an ESP32 primary aggregator, and a Raspberry Pi 4 gateway, integrating ESP-NOW for local ultra-low-power communication and LoRa for long-range data transmission. In operation, the ESP8266 nodes periodically acquire environmental data and send it via ESP-NOW to the ESP32 primary, which aggregates the packets and forwards them through LoRa to the Raspberry Pi gateway for storage, visualization, and analysis. All sensor data are stored in a MySQL database and visualized in real time through a web dashboard. The sensing modules were calibrated under laboratory conditions using reference instruments to ensure accuracy, achieving correlation coefficients (R²) between 0.95 and 0.97. Field deployment in a Tunisian wheat plot further confirmed stable performance, with less than 3% nighttime battery discharge and a packet delivery ratio above 95% up to 2 km. Costing under 600 EUR, the proposed system provides a validated, scalable, and affordable IoT solution for precision agriculture in resource-constrained environments.