A case study was carried out during 1994–99 in north east India and it was found that introduction of appropriate mechanization to various types of land could provide sustainability to agriculture. The small tractor (20 hp), power tillers and bullocks were found suitable for foot hill land, whereas medium size tractor (35 hp) for plain valley and river bank. He-buffaloes were found suitable for waterlogged areas and swamps. The human labour was found to be an appropriate source of farm power for hill slope. The large size tractor (45 hp) could do subsoiling and uprooting of old tea bushes and medium size tractor (35 hp) performed all transport operations on tea gardens.
