We have to find how many fields the farmer has.
The total land is 1.5 square mile.
If the fields have dimensions of 1/4 mile by 1/4 mile, the field area will be:

We can now calculate the maximum number of fields as the quotient of the total area and the area of the field:

If the length and width of the land is multiple of 1/4 miles, the number of fields can be 24.
Answer: 24 fields