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Agriculture IoT 22 min read

Smart Agriculture: Soil Moisture Monitoring with LoRaWAN

Build a long-range, low-power soil moisture monitoring network for precision agriculture with automated irrigation control.

1. Project Overview

This project builds a complete smart agriculture system using LoRaWAN technology for long-range, low-power soil moisture monitoring across large fields. The system includes automated irrigation control based on soil conditions.

2. Required Components

3. Understanding LoRaWAN

LoRaWAN (Long Range Wide Area Network) is perfect for agriculture IoT:

• Range: 2-5 km in rural areas, 10+ km line-of-sight
• Battery Life: 2-5 years on a single charge
• Penetration: Excellent through crops and obstacles
• Cost: Free to use (unlicensed spectrum)

4. Soil Sensor Setup

// ESP32 LoRaWAN Soil Moisture Node
#include <SPI.h>
#include <LoRaWan.h>
#include <Adafruit_SleepyDog.h>

#define SOIL_SENSOR_PIN 34
#define LORA_BAND 915E6  // Change for your region

// Calibration values
#define SOIL_DRY 3000
#define SOIL_WET 1500

void setup() {
  Serial.begin(115200);
  pinMode(SOIL_SENSOR_PIN, INPUT);
  
  // Initialize LoRa
  if (!LoRa.begin(LORA_BAND)) {
    Serial.println("LoRa init failed!");
    while (1);
  }
  
  // Join LoRaWAN network (OTAA)
  joinNetwork();
}

void loop() {
  // Read soil moisture
  int sensorValue = analogRead(SOIL_SENSOR_PIN);
  float moisture = map(sensorValue, SOIL_DRY, SOIL_WET, 0, 100);
  moisture = constrain(moisture, 0, 100);
  
  // Send via LoRaWAN
  sendMoistureData(moisture);
  
  // Deep sleep for 30 minutes
  enterDeepSleep(30 * 60 * 1000);
}

void sendMoistureData(float moisture) {
  LoRa.beginPacket();
  LoRa.print("MOIST:");
  LoRa.print(moisture);
  LoRa.endPacket();
  Serial.println("Data sent");
}

5. LoRaWAN Gateway Setup

Set up a Raspberry Pi-based gateway:

# Install ChirpStack Gateway Bridge
wget https://downloads.chirpstack.io/gateway-bridge/latest/chirpstack-gateway-bridge.deb
sudo dpkg -i chirpstack-gateway-bridge.deb

# Configure for your concentrator
sudo nano /etc/chirpstack-gateway-bridge/chirpstack-gateway-bridge.toml

6. Network Server Configuration

Use The Things Network (TTN) or self-hosted ChirpStack:

• Register your gateway on TTN console
• Create application and device
• Configure OTAA credentials (DevEUI, AppEUI, AppKey)
• Set up payload decoder

7. Dashboard & Alerts

Integrate with Grafana or custom dashboard:

// Node-RED flow for TTN integration
[
  {
    "id": "ttn-input",
    "type": "ttn up",
    "name": "TTN Up",
    "app": "your-app-id"
  },
  {
    "id": "dashboard",
    "type": "ui_chart",
    "name": "Soil Moisture Chart"
  }
]

8. Automated Irrigation

Set up automatic watering based on thresholds:

// Irrigation automation logic
if (moisture < 30) {
  // Soil too dry - start irrigation
  digitalWrite(VALVE_PIN, HIGH);
  sendAlert("Irrigation started - Field Zone 1");
} else if (moisture > 70) {
  // Soil wet enough - stop irrigation
  digitalWrite(VALVE_PIN, LOW);
  sendAlert("Irrigation stopped - Field Zone 1");
}

9. Solar Power Setup

10. Field Deployment

• Bury soil sensor at root depth (15-30 cm)
• Place gateway at highest point for best coverage
• Use UV-resistant enclosures
• Install lightning protection
• Test range before final deployment

11. Troubleshooting

Poor LoRa Range

• Elevate gateway antenna
• Use higher gain antenna (5-8 dBi)
• Check for interference sources
• Verify frequency settings

Sensor Reading Issues

• Calibrate sensor for your soil type
• Ensure good soil contact
• Check for corrosion on probes
• Verify power supply stability