At the close of the eighteenth and beginning of the nineteenth centuries, plow designs rapidly improved as more iron, and later steel, were used. The first development came with the hardening of cast iron plowshares. Robert Ransome invented a process whereby one surface was cooled more quickly resulting in a plowshare that was self-sharpening through use.
Next the moldboard of the plow and later the entire implement were made of replaceable iron parts. At the close of this period, in 1846, John Deere built a plow with a steel moldboard.
These developments permit Farmers to improve Grain and Produce farms to Level II. Farms will produce three units per turn.
