The wasteland glitch is a bug in the C3/DS engine. Whenever a geat looks at another geat, the nearby rooms change type to become "air" rooms. This can cause problems with the ecology because several plants can only grow in soil-type rooms. It is also possible that the game will instantly crash instead of altering room types.
The exact workings of the glitch are not confirmed, but it is specifically triggered by any agent with the geat classifier. Changing the classifier of a geat using the CATO command will no longer trigger the bug. It is currently unknown what circumstances are required to prevent a game crash, but it seems to be on a world-to-world basis.
Vermidia created a rudimentary fix for this glitch that forces all geats to be classified as machines. It can be found here.