on what basis have cultivation methods changed significantly in India?

Cultivation methods have changed depending upon the physical environment, technical know-how and socio-cultural practices. Over time, from ancient times to the present day, there have been significant changes in the technical know-how. The socio-cultural practices have evolved and continues to change. The physical environment also changes due to human interference like the fertility of the soil varies, and due to natural causes like rivers change course. So changes in these fields force changes in cultivation methods and patterns.