Shifting cultivation is an agricultural system in which plots of land are cultivated temporarily, then abandoned and allowed to revert to their natural vegetation while the cultivator moves on to another plot.

 When you cultivate a crop the plants take some nutrients out of the soil, and put some into the soil. Shifting cultivation helps to keep a good amount of diverse nutrients in the soil.
One crop might take all of the nitrates out of the soil so after a year or two you have no nitrates in that area and the plant will not grow well. This is when you would either leave that area alone for a few years or plant a crop that puts nitrates back into the soil. Crop rotation is key in large-scale, long term operations.

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Shifting cultivation which change after some period and they move to other piece of land for cultivation
advantage 1. no need of pesticide 
2.they cut and burn trees for the humus and fertility
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