earthboard

from The Century Dictionary.

• noun The board of a plow that turns over the earth; the mold-board.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Agric.) The part of a plow, or other implement, that turns over the earth; the moldboard.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The part of a plough or other implement that turns over the earth; the moldboard.