Dog-urine spots in lawn are due to the high level of nitrogen in the dog urine; that is what burns the grass. The urine doe not cause a high pH in the area. Adding gypsum certainly will not correct this problem. Washing the excess nitrogen out of the soil with water will help the grass recover. If the grass is tall fescue or perennial ryegrass, it will need to be reseeded in those areas once the excess nitrogen has been leached out of the soil. If the grass is Kentucky bluegrass, the lawn will recover without reseeding but only after the nitrogen level is reduced by leaching with water.
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