Question

1 inch of rain per year or less in grassland? Is this a lot or a little of rain?

Answer 1

it is actually very little for the grassland

Answer 2

1 inch of rain per year is less than many of the world's most arid places get.
That's a real desert, and probably could not support any grass.

In the Sahara desert, which occupies half of the continent of Africa, the
annual rainfall ranges from 0.8 to 3.9 inches per year. You can see that
1 inch per year is near the bottom of the Sahara's range !