Misc: a square mile of fertile ---------- has 32,000,000 earthworms in it?

Questions

Approximately 1/3 of the Earth's land surface is---------- .?

At latitude ---------- degrees south you can sail all the way around the world.?

Australia is the richest source of mineral ---------- in the world.?

Because of a large orbital eccentricity, ---------- was closer to the sun than Neptune between January 1979 and March 1999.?

Because of heavy---------- , Julius Caesar banned all wheeled vehicles from Rome during daylight hours.?