China feeds a fifth of the world’s population from only less than one tenth of the arable land across the globe.
The need to feed its population has always been a concern of China’s rulers. As early as the Tang (618-907) and Song (960-1279) dynasties, the imperial government was encouraging people to expand food production beyond the fertile lowlands into the mountains.
Time-honored paddies
For areas growing rice, a semi-aquatic plant needing rooting in clear water, the technical challenges were formidable. However, by the time of the Northern Song Dynasty (960-1127), there is documentary evidence of well-watered rice fields that were carved in a step-like fashion into mountain slopes as steep as 40 degrees. The spectacular rice terraces of Ziquejie in
