if its pure sand your wasting your time sand doesn't retain moisture or nutrients and even if its a real sandy loam meaning it does have some organic matter in it you would have to water it a lot as well as fertilizing and then the water washes away the fertilizer it would be tough and a lot of effort on 1/2 acre. I'm assuming your in a southern /warmer zone if so even tougher

It would help to know where you are, a close nearby city.

Millions of gulf coast residents would beg to differ with oldgardenguy. In fact sand is my primary fill material. The grass seems to grow better on sand.

Where do you live?

What kind of grass would you like to grow?

What are you planning to use the lawn for (just looking at, kids playing, adult baseball, etc.)?

Do you have animals that like to dig?

It’s difficult to grow grass in sand, but it also depends on the temperature and climatic conditions. Could you specify which zone or city you are in?