Dry Dirt is an in-game feature of antwar.io, and it can be found underground. There are markings on the surface that indicate the presence of dry dirt. It's a great spot to store food as food will spoil unless it's placed on top of dry dirt.
After 500 "uses" the tile will become regular dirt. One use is counted as a single piece of food being on a tile at the end of an 8 second period. Placing multiple pieces of food on a tile will speed up this process.