Crop rotation

Crop rotation is the practice of growing different crops in succession on the same piece of land. Crop roation is a key strategy for reducing pests and disease in the soil and for managing fertility through the use of legumes and other nitrogen fixing plants. Crop rotation may also be practiced to maximize the growing season, for example, by planting an early spring crop which is harvested in time to plant a fall crop.

Crop rotations of traditional East Asian agriculture

In his masterful 1911 book, Farmers of Forty Centuries: Or Permanent Agriculture in China, Korea and Japan, Soil scientist Franklin Hiram King recorded several crop rotations in use in the traditional agriculture of the Far East:

• "In Chekiang province there may be a crop of rape, of wheat or barley or of windsor beans or clover which is followed in midsummer by another of cotton or of rice"

• "In the Shantung province wheat or barley in the winter and spring may be followed in summer by large or small millet, sweet potatoes, soy beans or peanuts."

• "At Tientsin, 39 deg north, in the latitude of Cincinnati, Indianapolis, and Springfield, Illinois, we talked with a farmer who followed his crop of wheat on his small holding with one of onions and the onions with cabbage, realizing from the three crops at the rate of $163 ($4,015 in 2013), gold, per acre; and with another who planted Irish potatoes at the earliest opportunity in the spring, marketing them when small, and following these with radishes, the radishes with cabbage, realizing from the three crops at the rate of $203 ($5,001 in 2013) per acre."

• In Japan "Just before, or immediately after the rice crop is harvested, fields are often sowed to "clover" (Astragalus sinicus) which is allowed to grow until near the next transplanting time when it is either turned under directly, or more often stacked along the canals and saturated while doing so with soft mud dipped from the bottom of the canal. After fermenting twenty or thirty days it is applied to the field. And so it is literally true that these old world farmers whom we regard as ignorant, perhaps because they do not ride sulky plows as we do, have long included legumes in their crop rotation, regarding them as indispensable."