In 1992 I had my soil tested by the Cooperative Extension Service of the University of Maryland System. Do you still provide this service? At the time the soil pH was 5.1 and they recommended lime. How do I know if I still need lime and how much to apply. I live in the White Oak area of Silver Spring. Thanks.
Soil pH changes all the time. It generally gets lower and lower, in other words it gets more and more acid and needs lime to bring it up closer to 6.5 where vegetable gardens and lawns want it to be.
You'll need to have the soil tested again to determine the pH. The University of Maryland does not have a lab now, but we have a list of labs in our region that work well for homeowners.
They will give you a recommendation telling you exactly how much lime to apply to raise the pH. Soil pH changes slowly, so the sooner you test the better. It's not expensive and is faster than it used to be.
Here's our soil testing page telling how to collect the soil sample, what to test for, and some labs in our region to use: https://extension.umd.edu/hgic/soils/soil-testing