My farm life 2 question

Does anyone know how the spronklers work in my farm life 2, I have put them in my farm but nothing seem to happen I still have to water my crops ....if anyone know that answer please let me know ...Thanks a million

I just placed them and when the plant puts up the water droplet the sprinklers come on. I wish Farm Life the first one had them. I waste so much time watering!