When exposed to dog urine, which contains large quantities of nitrogen and nitrogen-rich salts, your lawn develops brown spots of dead grass. The concentrated nitrogen dehydrates the grass, killing it at the roots. Without regular dilution with water soon after the dog urinates on the grass, your lawn can wind up ruined and filled with these spots. If your lawn has been ruined by dog urine, repair small spots by resodding them with new grass or reseed the lawn to get it back into a healthy, hardy state.
Douse the brown spots with water from a garden hose to remove the nitrogen salts from the area. Soak the area well.
Remove the dead grass with a spade, sod-cutter or small hand-held shovel. Cut out the spot completely by pressing the cutting tool deep into the grass. Discard the dead grass.
Loosen the soil with a spade for smaller areas or rotary tiller for larger areas. Dig into the area, lifting the soil to stir it around.
Add seeding soil to the smaller bare spots or layer 1 inch of sand and 1 inch of compost in larger spots. Till the soil to loosen it.
Test the pH of the soil using a soil test kit or pH meter, found in plant nursery supply stores. The ideal pH for grass to grow is between 6.0 and 7.5. To obtain this reading for your soil if it doesn't fall within this range, add lime to soil with a pH under 6.0, peat moss to soil with a pH between 7.5 and 8.0, and sulfur to soil with a pH over 8.0. Use a broadcast spreader for larger areas to distribute the lime, sulfur or peat moss.
Sprinkle fertilizer over the soil to prepare it for new sod or seeds. Rake the fertilizer into the soil and level it with the rake.
Sprinkle the grass seeds over the area by hand for small spots and with a broadcast spreader for larger areas to equally distribute them over the soil.
Turn a rake upside down and run it over the area lightly.
Lightly water the area after sowing the seeds with sprinklers or a garden hose on a low-pressure setting to soak the area without washing the seeds away.
Water the seeds two to three times each day for 5 minutes at a time during the first 10 days after planting the seeds. Once the seeds sprout, water the emerging new grass once each day for 15 minutes.
Obtain a slab of sod from your local plant nursery. Cut pieces of it to fit the empty spots in your lawn.
Place the sod pieces over fresh soil and step on them to push them into the soil.
Water the new sod three times daily for 5 minutes at a time to prevent it from drying out. After the sod has taken root, in about 2 weeks, water the grass once each day for 10 to 15 minutes at a time.