The soil under the sod needs to have good drainage. If the location where you intend to lay sod has a problem with standing water, you need to amend the soil at least 4 to 6 inches deep with equal parts of peat moss and compost. If the soil is heavy with clay, do not add sand to the mixture, manure or compost.
Water the sod to keep the soil moist, but not wet. When the ground is wet all the time, the sod roots will rot. The sod needs at least 1 inch of water per day for the first two weeks when temperatures are above 70 degrees Fahrenheit and every other day when the temperatures are below that.
When patches or large areas of sod start to turn yellow or brown, it can be a sign of root rot. As the sod dies, weeds will start growing. If the sod shows signs of rot, you can test the sod for root establishment to determine if the problem is root rot. If the roots are solid in the ground and the sod is not continually wet and soggy, it could be the lack of nutrients in the soil or you mowed the grass when it was wet and the roots were ripped out of the soil.
After three weeks of watering the sod, gently lift up on one corner of the sod to check if the roots are established. If the sod lifts up easily, the roots are not established. If the sod doesn't lift up, the roots are establishing well. If you have to walk on the sod to place the sprinkler and notice the sod is soggy, don't water until the sod dries a little.