mouldboard

US moldboard

noun

the curved blade of a plough, which turns over the furrow

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Examples from the Web for mouldboard

Historical Examples of mouldboard

For breaking new land a plow with a long, gradually sloping share and mouldboard is used.
The First Book of Farming
Charles L. Goodrich