Saturday, September 29, 2012

What happened when American food crops got to China

In his book 1493: Uncovering the New World Columbus Created, Charles C. Mann devotes a chapter to the transfer of crops from the Americas to China and their impact. Tobacco was one of the crops transferred, and as the smoking habit swept China, more and more of its good land was diverted from food production to tobacco production.

Fortunately (or unfortunately) sweet potatos, maize, peanuts, potatoes, chili peppers, pineapples, cashews and cassava also came to China -- and many of these could be grown in areas not suited for rice and wheat, China's traditional food grain crops.

People who could not get land in the fertile low lands moved to the hills to grow these new crops. The population boomed, taking advantage of the flood of calories produced by the need food crops. People moved into less populated lands in the west of China.

Unfortunately, in clearing the hill sides and planting new crops, the Chinese increased water runoffs and erosion. For some time it was possible to move to new hillside areas when farmers exhausted the soil of their current lands. That alternative became increasingly difficult as population continued to increase and the area of land that could no longer support crops increased.

Flooding of the lowlands became much more common. Not only did the floods destroy irrigation infrastructure needed for rice culture, but it also left deposits of silt on the rice fields that decreased their productivity. Thus the pressure to grow still more food crops in fragile lands increased.

The result was a viscous cycle that has continued into modern times. Mao's Great Leap Forward resulted in massive use of labor to bring fragile lands into agricultural production, and then to massive environmental damage.

I was more familiar with the flow of new crops to Europe -- potatoes to Ireland and tomatoes to Italy -- and had not been aware that China is the world's greatest producer of sweet potatoes and second in the production of maize.

The fundamental point of the discussion is that the Colombian Exchange of plant species to China changed the physical environment, the size of the Chinese population, and ultimately the culture and the political institutions of China. Moreover, the plants made it to China as a side effect of the commerce that grew from the production of silver in the Americas that could be traded for silk, porcelain, spices and other Asian products in demand in Europe (and in Hispanic America).

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