Arduino Soil Moisture Sensor

Every year, Kenyan farmers lose crops because they water too much (causing root rot) or too little (causing drought stress). This project solves that problem by creating an automatic warning system: when soil gets too dry, a red LED lights up or a buzzer sounds. You are building a real "smart farming" device used by commercial farms worldwide.

Copy the entire code below. Paste into Arduino IDE, then click the Upload button (right arrow).

// SIMPLE SOIL MOISTURE SENSOR - FOR BEGINNERS
int sensorPin = 7;      // Soil sensor on pin 7
int ledPin = 8;         // LED on pin 8
int buzzerPin = 9;      // Buzzer on pin 9

void setup() {
  pinMode(sensorPin, INPUT);
  pinMode(ledPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  if (digitalRead(sensorPin) == 0) {
    Serial.println("SOIL IS WET - No alarm");
    digitalWrite(ledPin, LOW);
    digitalWrite(buzzerPin, LOW);
  } else {
    Serial.println("SOIL IS DRY - WATER YOUR PLANT!");
    digitalWrite(ledPin, HIGH);
    digitalWrite(buzzerPin, HIGH);
  }
  delay(500);
}
          

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• ❌ Upload error "Board not found": Check USB connection and select correct Port.
• 💡 LED always on: Sensor reading reversed. Swap LOW and HIGH in code for LED.
• 🌱 Sensor always reads "dry": Check VCC to 5V and GND to GND. Loose wires are #1 problem.
• 🔌 No red light on Arduino: USB cable may be power-only. Try different cable.