1. crush fertilizer pellets (fertilizer must have at least 32% nitrogen composition) into a fine powder
2. mix the powder with a 1:1 mixture of motor oil and gasoline (ratio of fuel to powder should be 1:16)
3. fill a small steel pipe with one endcap with the solution
4. place a blasting cap with a fuse (a firework can also be used) into the pipe
5. drill a hole in the other endcap and lead the fuse through the hole
6. thread the endcap onto the pipe