Answer: Your local nursery or garden center store may carry simple soil test kits to check soil pH (acidity.) Your local county extension should be able to help you with the testing and interpreting the results. Here is a listing of the county offices for North Carolina.
I should mention that NC soils tend to be naturally acidic, and the pine straw could also add to the acidity. Lawn grasses tend to prefer a less acid soil, so pH might be a part of the problem you are experiencing.
However, lawn grasses also need ample sun, fertility and moisture to grow and will not usually grow well in a shady area under trees with lots of roots. So acidity may be only one aspect of the difficulty in growing lawn under the trees.
You might discuss with your county extension whether or not the area under your trees is suited to lawn grass, or if a ground cover or natural mulch area might be more feasible. For example, leaving the pine straw in place serves as a natural mulch and helps feed the soil and trees naturally, it also keeps dust down much as a lawn would do but without the maintenance needs of a lawn. In an area where growing a healthy lawn is not possible, it might be workable solution.
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