Science and Technology of The Han Dynasty - Agriculture - Alternating Fields

Alternating Fields

Further information: Government of the Han Dynasty

During Emperor Wu's (r. 141–87 BCE) reign, the Grain Intendant Zhao Guo (趙過) invented the alternating fields system (daitianfa 代田法). For every mou of land—i.e. a thin but elongated strip of land measuring 1.38 m (4.5 ft) wide and 331 m (1085 ft) long, or an area of roughly 457 m2 (0.113 acres) —three low-lying furrows (quan 甽) that were each 0.23 m (0.7 ft) wide were sowed in straight lines with crop seed. While weeding in the summer, the loose soil of the ridges (long 壟) on either side of the furrows would gradually fall into the furrows, covering the sprouting crops and protecting them from wind and drought. Since the position of the furrows and ridges were reversed by the next year, this process was called the alternating fields system.

This system allowed crops to grow in straight lines from sowing to harvest, conserved moisture in the soil, and provided a stable annual yield for harvested crops. Zhao Guo first experimented with this system right outside the capital Chang'an, and once it proved successful, he sent out instructions for it to every commandery administrator, who were then responsible for disseminating these to the heads of every county, district, and hamlet in their commanderies. Sadao Nishijima speculates that the Imperial Counselor Sang Hongyang (d. 80 BCE) perhaps had a role in promoting this new system.

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 45,730 m2 (11.3 acres) of land in a single day.