Automatic Irrigation System Using Arduino

In this project, we will make an automatic irrigation system using Arduino microcontroller. Automatic Irrigation system monitors the soil moisture and depending on set points turns on/off the pump which is connected to the relay. This way you can keep soil moisture to a set point.

This system automatically waters the plants when we are on vacation. As we are setting the soil moisture level, we need not worry about too much of watering and the plants end up dying anyway.

The project is designed to develop an automatic irrigation system which switches the pump motor ON/OFF on sensing the moisture content of the soil. This project requires Arduino board having inbuilt ATMega328

An automated irrigation system will minimize the excess wastage of water and the labor and other overheads.

In the field of agriculture, use of a proper method of irrigation is important. The advantage of using this method is to reduce human intervention and still ensure proper irrigation.

Components Required for this Project

You need the following items to complete this project.
  1. Arduino Uno
  2. Soil moisture sensor
  3. 16×2 LCD
  4. 1K, 220E Resistors
  5. 12V Relay
  6. BC548 Transistor
  7. Switches

Automatic Irrigation System Circuit



LCD displays the current moisture level and set point. The setpoint can be adjusted using push buttons. Connect relay output to the water pump. Put soil moisture tip in the soil where you want to maintain soil moisture.

Working of Automatic Irrigation System

The soil moisture sensor senses the moisture present in the soil and gives the output to Arduino. The output of the sensor will be from 0-1023. The moisture is measured in percentage, therefore we should map these values to 0-100.
Whenever the moisture value is lower than the value we have set inside our code as the threshold value, the relay will turn ON and the valve will turn open and whenever the moisture value is lower than this threshold value, the relay will relay will turn OFF and the valve will get closed.

 Automatic Irrigation System Arduino Code

Automatic Irrigation System
#include <LiquidCrystal.h>
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd (9, 8, 7, 6, 5, 4);
const int LED_RED =10; //Red LED
const int LED_GREEN =11; //Green LED
const int RELAY =12; //Lock Relay or motor
//Key connections with arduino
const int up_key=3;
const int down_key=2;
int SetPoint =30;
void setup (){
pinMode ( LED_RED , OUTPUT );
pinMode ( LED_GREEN , OUTPUT );
pinMode ( RELAY , OUTPUT );
pinMode ( up_key, INPUT );
pinMode ( down_key, INPUT );
//Pull up for setpoint keys
digitalWrite ( up_key, HIGH );
digitalWrite ( down_key, HIGH );
// set up the LCD's number of columns and rows:
lcd . begin(16, 2);
// Print a message to the LCD.
lcd . print ("");
lcd . setCursor (0,1); //Move coursor to second Line
lcd . print (" Irrigation ");
lcd . setCursor (0,1);
lcd . print (" System ");
digitalWrite ( LED_GREEN , HIGH ); //Green LED Off
 digitalWrite ( LED_RED , LOW ); //Red LED On
digitalWrite ( RELAY , LOW ); //Turn off Relay
void loop (){
double WaterLevel = ((100.0/1024.0) * analogRead ( A0 )); //Map it in 0 to 100%
lcd . setCursor (0,0);
lcd . print ("Water :"); //Do not display entered keys
lcd . print ( WaterLevel );
lcd . print ("% ");
//Get user input for setpoints
if( digitalRead ( down_key)== LOW )
if( SetPoint >0) //Not less than zero
SetPoint --;
if( digitalRead ( up_key)== LOW )
if( SetPoint <99) //Not more than 100%
SetPoint ++;
//Display Set point on LCD
lcd . setCursor (0,1);
lcd . print ("Set Point:");
lcd . print ( SetPoint );
lcd . print ("% ");
//Check Temperature is in limit
if( WaterLevel > SetPoint )
digitalWrite ( RELAY , LOW ); //Turn off water pump
digitalWrite ( LED_RED , HIGH );
digitalWrite ( LED_GREEN , LOW ); //Turn on Green LED
digitalWrite ( RELAY , HIGH ); //Turn on water pump
digitalWrite ( LED_GREEN , HIGH );
digitalWrite ( LED_RED , LOW ); //Turn on RED LED
delay(100); //Update at every 100mSeconds

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