right, how do you expect to blow up a million zombies with only a truck of dynamite, plus each explosion attracts more zombies, do note that a ton of dynamite could only blow up about 100meter radius of zombies(see terrorist movies that has a van loaded with explosives only blowing up a small area), oh right i wonder how'd you buy and carry tons of dynamite with the shortage of productions of it, riiiiiiiiight you magically have some.
if you'd plan to detonate a nuke, then be my guess, goodluck surviving the blast radius and the fallout, oh and the legal papers to acquire one. not even terrorists has one.
my point is, sure its great on paper, but on practice, its impossible, since having tons of explosives is illegal, nor does acquiring some is easy, plus its hard to move around with bulky explosives that could screw you over anytime because you kept attracting more zombies.