HI. I Live on the Gulf Coast in Mississippi in an old house that is about 1 1/2 feet off of the ground. The underneath of the house is packed dirt. We have lived her for about a year and the entire time we have had this horrible smell coming from under the house. When it's REALLY hot it smells like a dead animal. When it's cooler it just smells like urine or mold. We have opened up the underneath of the house for months, but the smell has not gone away and now it seems to be permeating the the entry way and the interior of the house. I would really like to know how to get this smell to go away without having to dig up the underneath of the house (because this is impossible). We have crawled under there and there is nothing but dirt and the actual wood on the bottom of the house does not seem to be affected.
My big problem is that I have outside cats and I need to spread something that will not be harmful to them or scare them away.
Thanks

If you have proper ventilation below the house in the crawl area I doubt your issue is from the soil in the ground. DO you have any nesting critters in the floor joists, assuming they are covered over by plywood and insulation? Many years ago I lived in a converted barn. The rodents had chewed into the wall cavities of the building over the years. As they died in the wall cavities we would get some lovely smells as the sun would heat the walls they were in. Once we corrected the rodent issue, these foul odors went away. Have an exterminator check the house out. I think that may be your issue.

I guess I will take a closer look, but there really isn't anywhere for anything to hide under there because the house isn't even insulated underneath-it's just plywood. Plus, I have about 10 healthy cats living outside in my backyard (not in a creepy way) and they keep all the critters away.
hmmmm....

Cats = Smells. The tom cats are marking their area. And using the crawl as the litter box. You do not see it because they bury their mess.

Remove the cat access below the house and you will remove the smell. You can purchase chemicals at your local pet shop that will remove these types of odors. You would need to spray the underside of the house until wet. That most likely will remove the odor.

As usual, Home Care Club gives good advice. I would add to first check for dead bodies (just joking, .....kinda) then to buy some big cheap boxes of baking soda and sprinkle liberally before covering the entire surface under the house with the thickest plastic you can afford. If it is the cats then that will dissuade them, as well as making it much more nice for you if you ever have to crawl under there to fix plumbing, run cables, etc. etc.