I got my license and started spraying yards for the public this year as a side job to make extra money. Business has been great and I'm staying busy spraying for weeds and ants but I keep getting asked by ppl if I can apply fertilizer. So I guess I'm about to attempt my first fertilizer job on a 4 acre centipede yard. This is what I told the guy: I'm going to pull a soil sample to fig out if I should apply 16-4-8 or 15-0-15, looks like it'll take a little over 6lbs per 1000 square feet to put out 1lb of nitrogen on that area. That means it will take between 270 / 290 lbs per acre. I'm estimating my cost around 75 per acre if my math on the amount needed is correct. Give me some feed back on how much should I charge for this. What should my profit be and any tips would be appreciated to help me get started adding this as one of my services.