Out of all the obscure jokes and references in Futurama, this one puzzles me the most: In The Luck of the Fryrish, the professor says that "dirt doesn't need luck" and looks very content. What does he mean by that?
We shouldn't read too much into this joke, but I believe there is an actual "science fiction answer" to this line.
Farnsworth is a scientist, and by extension a science buff. A better portion of this group (I'm afraid this includes me) likes to make Spockanian comments, state the obvious, technical corrections or wisecracks (call it what you like). In this instance he's correcting Fry's sentiment that the four-leafed clover is now bringing luck to some lump of dirt (something along those lines). This explains his content look, because he's correcting Fry allegedly thinking dirt would require the features provided by the clover (while this is without doubt obvious, even for Fry).
My take on this was that the Professor was claiming that soil was inherently lucky and so didn't need the extra luck that the clover would give.
Dirt like war is ever lasting it doesn't need luck because it is everlasting no matter how barren it may become it will always exist.