Code to detect soil moisture using arduino uno

soil_moisture.ino

#define SensorPin A0

float sensorValue = 0;
int sensorLimit = 597;
int piezoPin = 8;

void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT);
}

void loop() {
  for (int i = 0; i <= 100; i++) {
    sensorValue = sensorValue + analogRead(SensorPin);
    delay(1);
  }
  sensorValue = sensorValue / 100.0;
  Serial.println(sensorValue);
  if (sensorValue < sensorLimit) {
    digitalWrite(13, HIGH);
    tone(piezoPin, 50, 200);
   } else {
    digitalWrite(13, LOW);
    }
  delay(5000);
}