Ok here is a glitch that sucks... If some other people could try it out and post here your results that would be great. So you start out by, drop a bomb, pick it up toss it, drop another bombs(even before the last one blows up) pick it up and throw it. Repeat... After you throw your 3ed or 4th bomb, it will start to use 2 bombs instead of just one. Watch your bomb number, it'll start out 30,29,28, then to 26, 24,22,20,ect. So please test this once for me, and let me know if it happens to you too.  

Why don't you just avoid doing the incredibly long process?  

Well you see it doesn't actually have to be fast. So to stand there and throw bombs into your farm is actually wasting bombs. I feel this is something that should really be looked into