Answer: What you describe sounds like a sedge rather than a grass. If so, it will be difficult to eradicate without killing the adjacent grass so your best approach might be to dig the offending weed out, roots and all. Sedges have extensive root systems with storage areas (tubers) so you'll want to get all of the roots out. Once that's done, fill the holes with garden soil and reseed the area. After reseeding you can put your lawn on a regular watering, mowing and feeding schedule which will promote a lush, thick lawn - one that will crowd out future weeds. Plan on feeding in April, June, September and late November. Aerating can be done in spring or in fall.
Best wishes with your lawn!
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