soil.py

#!/usr/bin/python
import RPi.GPIO as GPIO
import time
 
#GPIO SETUP
channel = 21
GPIO.setmode(GPIO.BCM)
GPIO.setup(channel, GPIO.IN)
 
def moisture_detect(channel):
  if GPIO.input(channel):
          print "No moisture detected"
  else:
          print "Moisture Detected!"
 
GPIO.add_event_detect(channel, GPIO.BOTH, callback=moisture_detect)
 
# infinite loop
while True:
  print "loop"
  time.sleep(1)