Mixed cropping, also known as inter-cropping or co-cultivation, is a type of agriculture that involves planting two or more of plants simultaneously in the same field. In general, the theory is that planting multiple crops at once will allow the crops to work together. Possible benefits of mixed cropping are to balance input and outgo of soil nutrients, to keep down weeds and insect pests, to resist climate extremes (wet, dry, hot, cold), to suppress plant diseases, to increase overall productivity and to use scarce resources to the fullest degree.
Mixed Cropping in Prehistory
Monocultural cropping is a recent invention of the industrial agricultural complex: it is thought that most agricultural field systems of the past involved some form of mixed cropping, although unambiguous archaeological evidence of this is difficult to come by. Even if archaeological evidence of multiple crops are discovered in a field, it would be difficult to differentiate between the results of mixed cropping and rotation cropping. Both methods are believed to have been used in the past.
The primary reason for prehistoric multi-cropping probably had more to do with the needs of the farmer's family, rather than any recognition that mixed cropping was a good idea. It is possible that certain plants became amenable to multicropping over time, as a result of the domestication process.
Classic Mixed Cropping: Three Sisters
The classic example of mixed cropping is that of the American "three sisters", maize, beans, and curcurbits (squash and pumpkins). These three plants, domesticated at different times, were together an important component of Native American agriculture, historically documented by the Seneca and Iroquois, and probably beginning sometime after 1000 AD. All three seeds are planted in the same hole. The maize provides a stalk for the beans to climb on, the beans are nutrient-rich to offset that taken out by the maize, and the squash grows low to the ground to keep weeds down and water from evaporating from the soil in the heat.
Modern Mixed Cropping
Agronomists studying mixed crops have had mixed results determining if yield differences can be achieved with mixed versus monoculture crops. If a combination of say, wheat and chickpeas works in one part of the world, it might not work in another. But, overall it appears that measurably good effects result, when the right combination of crops are cropped together.
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