shifting cultivation is requires

1. alternate crop pattern on a perticular area
2. huge amount of commercial fertilizer
3. excessive soil erosion for crop production
4. long time for the regeneration of soil

Shifting cultivationis anagriculturalsystem 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. The period of cultivation is usually terminated when the soil shows signs of exhaustion or, more commonly, when the field is overrun by weeds. The length of time that a field is cultivated is usually shorter than the period over which the land is allowed to regenerate by lying fallow. So option 4 is correct.