Soil Moisture Sensors
Complete guide to measuring soil moisture with resistive sensors
Complete guide to measuring soil moisture with resistive sensors
Soil moisture sensors measure the water content in soil by detecting changes in electrical resistance between two conductive probes.
| Operating Voltage | 3.3V-5V |
| Output Signal | Analog & Digital |
| Probe Length | 5cm-10cm (typical) |
| Current Consumption | ~35mA |
| Interface | PH2.0-3P connector |
// Basic Soil Moisture Sensor Example
#define SOIL_MOISTURE_PIN A0
void setup() {
Serial.begin(9600);
}
void loop() {
int moistureValue = analogRead(SOIL_MOISTURE_PIN);
int moisturePercent = map(moistureValue, 1023, 300, 0, 100);
Serial.print("Raw Value: ");
Serial.print(moistureValue);
Serial.print(" | Moisture: ");
Serial.print(moisturePercent);
Serial.println("%");
delay(1000);
}// Soil Moisture with Calibration
#define SOIL_PIN A0
int dryValue = 1023; // Value in dry soil
int wetValue = 300; // Value in wet soil
void setup() {
Serial.begin(9600);
calibrateSensor();
}
void calibrateSensor() {
Serial.println("Dry calibration - place sensor in dry soil and enter value:");
while(!Serial.available());
dryValue = Serial.parseInt();
Serial.println("Wet calibration - place sensor in wet soil and enter value:");
while(!Serial.available());
wetValue = Serial.parseInt();
Serial.print("Calibration complete. Dry: ");
Serial.print(dryValue);
Serial.print(" Wet: ");
Serial.println(wetValue);
}
void loop() {
int sensorValue = analogRead(SOIL_PIN);
int moisturePercent = map(sensorValue, dryValue, wetValue, 0, 100);
moisturePercent = constrain(moisturePercent, 0, 100);
Serial.print("Soil Moisture: ");
Serial.print(moisturePercent);
Serial.println("%");
delay(2000);
}// Automatic Plant Watering System
#define SOIL_PIN A0
#define RELAY_PIN 3
#define THRESHOLD 30 // Water when moisture < 30%
void setup() {
pinMode(RELAY_PIN, OUTPUT);
digitalWrite(RELAY_PIN, HIGH); // Start with pump off
Serial.begin(9600);
}
void loop() {
int moisture = readMoisture();
if(moisture < THRESHOLD) {
waterPlant();
}
delay(3600000); // Check every hour
}
int readMoisture() {
int sensorValue = analogRead(SOIL_PIN);
return map(sensorValue, 1023, 300, 0, 100);
}
void waterPlant() {
Serial.println("Watering plant...");
digitalWrite(RELAY_PIN, LOW); // Turn pump on
delay(5000); // Water for 5 seconds
digitalWrite(RELAY_PIN, HIGH); // Turn pump off
Serial.println("Watering complete");
}Monitor soil moisture and alert when watering is needed.
Water plants automatically when soil gets dry.
Track soil moisture remotely with WiFi/Bluetooth.
Record soil moisture over time for analysis.
Monitor several plants with one controller.
Automate moisture, temp, and humidity.
// Components needed:
- Multiple soil moisture sensors
- ESP32 with LoRa
- Solar power system
- Water valve control
- Weather station sensors
- Cloud database
// Features:
1. Distributed soil moisture monitoring
2. Weather-based irrigation
3. Remote monitoring via web/mobile
4. Water usage optimization
5. Predictive watering
6. Alert system
// Implementation Tips:
- Use sleep modes for battery operation
- Implement mesh networking for large areas
- Add rain detection to skip watering
- Create moisture maps of fields
- Integrate weather forecasts
- Add manual override capability| Mistake | Consequence | Solution |
|---|---|---|
| No calibration | Inaccurate readings | Always calibrate for your specific soil |
| Continuous power | Probe corrosion | Power only when taking readings |
| Poor probe placement | Irrelevant measurements | Place near root zone |
| Ignoring soil type | Wrong moisture assessment | Adjust thresholds for soil characteristics |
| No maintenance | Degraded performance | Regular cleaning and inspection |