I intended to apply Lesco 18-24-12 with a Lesco rotary spreader over approx 60k area. I dialed the spreader using the lesco calibration guage to #15 as indicated on the bag. Each bag covers 12/k . I expected to use about 5 bags of product at this rate. I only used 1.25 bags. Its been awhile since I applied fert... ..but.....i could tell right away something was not right. The spreader is new. I am confused to say the least. I tried to do everything buy the book. Any help or suggestions would be appreciated.