NEW DELHI—Each fall at harvest time, Leela Dhar Rajput used to hire 25 farm hands to work from dawn to dusk every day for a week bringing in the rice crop on his 20 acres of land in the central Indian state of Madhya Pradesh.

This year, he plans to use a combine harvester instead. With the machine and the help of two or three men, he expects to finish the job in a single day.

Indian...