Now that you know 3.8 lb of 26-5-10 fertilizer will cover 1000 sq ft, determine how many times 3.8 lb goes into 50 lb. 50 lb -- 3.8 lb = 13.2. Now multiply 13.2 by 1000 sq ft: 13.2 -- 1000 sq ft = 13,200 sq ft. Thus, a 50-lb bag of 26-5-10 covers 13,200 sq ft at a rate of 1.0 lb nitrogen per 1000 sq ft.read more >>