Cui Shi
Rich families who owned oxen and large heavy moldboard iron plows greatly benefited from this new system. However, poorer farmers who did not own oxen resorted to using teams of men to move a single plow, which was exhausting work. The author Cui Shi (催寔) (d. 170 CE) wrote in his "Simin yueling" (四民月令) that by the Eastern Han Era (25–220 CE) an improved plow was invented which needed only one man to control it, two oxen to pull it, had three plowshares, a seed box for the drills, a tool which turned down the soil, and could sow roughly of land in a single day.