An irrgation system comprises: (1) a central rotatable bearing structure, (2) a main water beam with its inner end connected to the central rotatable bearing structure, (3) a long extending beam withits inner end connected to the outer end of the main beam and rested on a drive controllable rack, (4) a corner and spanning arm sensor is used to measure the angle between the extending beam and main beam. Several first sprinkers and several second sprinklers are installed on above mentioned extending water pipes along the direction in length, if water gunjet got turned on at the end of the extending beam, the second sprinklers will spray water for period of time.