Question

plateau regions in India do not support agriculture as much as the plain regions-what are the reasons for this?

Answer 1

Plateau regions does not have much fertile soil as plain areas, In plain areas irrigation facility is also good, as plain areas lie under the Himalayas. 

Answer 2

plateau regions do not support agriculture because the plains are more fertile and the plateaus are less fertile also plains like northern plains provide more irrigation facilities like river Ganges as compared to plateau regions.