The Agricultural Revolution Under Emperor Wu

During the late reign of Emperor Wu of the Han Dynasty (141–87 BCE), China faced pressing agricultural challenges. Traditional farming methods were inefficient, relying on slash-and-burn techniques and frequent fallow periods to restore soil fertility. Land productivity stagnated, threatening food security for a growing population. Recognizing this crisis, Emperor Wu appointed Zhao Guo as Sousu Duwei (Commissioner of Grain Procurement), tasking him with revolutionizing agricultural practices.

Zhao Guo, a visionary agronomist, studied peasant farming methods across the empire. His work culminated in two groundbreaking contributions: the Daitian (Rotational Field) system and innovative farming tools that transformed Han agriculture from subsistence to sustained productivity.

The Daitian System: A Masterstroke of Soil Management

Prior to Zhao Guo’s reforms, farmers sowed seeds haphazardly in untilled fields, leading to rapid soil exhaustion. The Daitian method introduced systematic land division:
– Each mu (a Han-era unit measuring 100 paces long × 1 pace wide) was split into alternating ridges (long) and furrows (zhen), each 1 Chinese foot wide.
– Seeds were planted in the furrows, which were 1 foot deeper than the ridges. As crops grew, soil from the ridges was gradually scraped into the furrows to protect roots from wind and drought.
– Annually, ridges and furrows swapped positions, allowing continuous cultivation without full-field fallow.

This ingenious rotation maintained soil fertility while boosting yields—Daitian fields consistently outperformed traditional plots by 1–2 hu (10–20 bushels) per mu. The system spread rapidly through government demonstration farms, where Zhao Guo trained local officials to teach peasants.

Engineering the Future: Zhao Guo’s Agricultural Tools

Zhao Guo’s mechanical inventions addressed labor shortages and inefficiencies:

1. The Coupled Plow (Ouli)
– Pulled by two oxen with three operators (one guiding the oxen, two steering plows), it could cultivate 500 mu annually.
– A human-powered variant enabled small farmers without livestock to till 13–30 mu daily.

2. The Multi-Tube Seed Drill (Louche)
– This revolutionary device combined plowing and seeding. A seed hopper fed grains through hollow plowshares into furrows simultaneously.
– Operators could sow 100 mu per day—a tenfold increase over manual methods.

These tools democratized high-yield farming, particularly in the arid northwest frontiers where military settlements relied on efficient agriculture.

Cultural Impact: From Subsistence to Surplus

Zhao Guo’s reforms rippled through Han society:
– Economic Stability: Increased grain production supported urbanization and standing armies, underpinning Emperor Wu’s expansionist policies.
– Social Mobility: Tenant farmers gained surplus to pay rents in cash rather than labor, weakening aristocratic control.
– Technological Legacy: The louche seed drill influenced designs as far as 18th-century Europe, while crop rotation principles endured for millennia.

Su Wu: The Unbreakable Diplomat

Parallel to Zhao Guo’s agrarian triumphs unfolded the epic of Su Wu, whose steadfast loyalty became a Confucian ideal.

A Mission Gone Awry

In 101 BCE, Emperor Wu dispatched Su Wu to the Xiongnu confederacy to reciprocate a peace overture. The diplomat’s integrity was soon tested when a rogue plot—involving his deputy Zhang Sheng—to kidnap the Xiongnu Chanyu (ruler) was uncovered. Though innocent, Su Wu chose ritual suicide over dishonor, stabbing himself before interrogation. His survival after massive blood loss astonished even his captors.

Nineteen Years of Defiance

The Chanyu, impressed but frustrated, subjected Su Wu to escalating trials:
– Imprisonment: Left in a freezing pit without food, Su Wu survived on snow and felt from his coat.
– Exile: Banished to Lake Baikal (then called Beihai) with a flock of rams, told he could leave only if they bore lambs.
– Isolation: Foraged wild seeds and resisted repeated inducements to betray Han, clutching his frayed imperial staff (hanjie) as a symbol of loyalty.

The Homecoming of a Legend

In 81 BCE, after Han diplomats exposed the Xiongnu’s deception about Su Wu’s death, the white-haired envoy finally returned to Chang’an. His 19-year ordeal, commemorated in poetry and art, epitomized the Confucian virtues of zhong (loyalty) and jie (moral integrity).

Enduring Legacies

– Zhao Guo’s techniques sustained Chinese agriculture through dynastic cycles, with the Daitian system echoing in modern crop rotation.
– Su Wu’s story became a cultural touchstone, inspiring resistance against foreign coercion from the Song Dynasty to WWII.

Together, these figures embody the Han Dynasty’s dual pillars: pragmatic innovation and unyielding moral courage. Their stories remind us that progress springs not just from tools, but from the indomitable human spirit.