If you're growing crops on fields, plowing is pretty important. Traditional music being mostly written by and for people working in agriculture, there's a lot of music about plowing, including at least four tunes called "Speed the Plow":

English

(link; another one)

This is the most commonly played tune by this name, and is the one in NEFR. It's played over a wide range of tempos, from slow hornpipes to contra dance speed.

Old Time #1

(link; another one)

I'll occasionally hear this version from American Old-Time musicians. Usually played on a cross-tuned fiddle with a lot of open strings.

Old Time #2

(link; another one)

This is my favorite version, and the one the Free Raisins play.

Irish

(link; another one)

I hadn't heard this one before looking through variations for this post.

Swedish

(link; another one)