Concept:
Electric motors are widely used in agriculture for pumping, processing, milling, threshing, and other operations.
Step 1: Agricultural motors should be simple, rugged, reliable, and easy to maintain.
Step 2: Induction motors are commonly used because they have simple construction and good operating performance.
Step 3: They can operate at nearly constant speed under normal load conditions.
Step 4: They are available in different horse power ratings according to the farm operation requirement.
Step 5: Hence, the most popular motor used for agricultural purposes is induction motor.
\[
\boxed{\text{Induction motor}}
\]