backyard damp
i've noticed my yard especially the backyard isn't drying even though not muddy but when walking on it you can feel your shoes sinking a little , haven't had all that much rain and been in the 50's f most days of course colder at night.. i don't remember this in past winters in georgia . one of my leyland cypress maybe 5 foot tall has even tipped over because of the damp soil.
A couple of things could happen...look at the lay (elevation changes) shape your yard for directional flow; has your grass lifted due to watering practices; do you have a pipe leak? Turn off all the water faucets in your house / shop and go check the water meter. Most have a low flow indicator that turns indicating a leak somewhere in your system. Good luck...its a pain.
Has the ground got compacted over the years so it doesn't drain so well and if you think it could be use a garden fork to make holes to the full depth of the tynes for a medium size patch to see if that helps and if it does hire/buy a correct tool and some sharp sand to fill the holes in and doo all the grass.
If you haven't had your tank cleaned out or checked and made sure you don't have a water line leak. It is more than likely you need your tank pumped out and.
If you have just a wet soft spot then it could be a water leak and if you have a dry spell in the summer the grass will stay growing as well. Also if it is a problem with your septic tank you will find the grass will grow faster due to the grass having more feed than other parts of the grass.
i went down in my yard yesterday and i'm just guessing because it slopes down in the back it is just collecting there , my neighbor was out back and we chatted his yard is more level he said it's somewhat wet but not slushy like mine. no water leak and no septic tank .