What makes the grass around a Yurt green?

[Onasander]

http://thumbs.dreamstime.com/x/tents-yurts-homes-local-nomadic-asian-people-dry-grass-mountain-valley-38301214.jpg

 

That picture reminds me of the archeological method of finding roman sites by the fauna diversity in a small area, apparently roman settlements caused a nitrogen upsurge in the ground that caused the land, once abandoned, to grow feral to a level of diversity that the lands not inhabited were unable to achieve.

 

I'm looking around the yurts, I can see dry grass everywhere, but green grass a good foot or two out around the yurts.

 

Why? Nitrogen? I dunno. I just assume the Romans were lazy slobs who left garbage outside, or dug latrines a lot. This isn't that case.

 

Water condensation? Maybe. People stumbling outside the yurt and just peeing there, perhaps? Unused broth or cooking liquids just dumped there?

 

Its a crazy difficulty to imagine archeologists trying to track actual huns, or any group across the steppe. But if we study WHY the grass grows greener around yurts, we may be able to determine what is needed to zoom in on exactly for aerial scans using some sort of scanner across the steppes, and map out historic population migrations. By mapping out, and following it up with digs, we might be able to map these movements chronologically. There might even be distinct chemical variables seen from afar that let's us figure it out without touching down for a dig.

 

This can give us important insights on how nomadic groups built themselves up and broke down, as well as insight as to why they periodically invaded China, Persia and Rome. Knowing this could fill gaps in Roman history. And possibly all it would take is a propeller plane, a spectrometer of some type, and a few archeological teams..... flying about, mapping grassy and desert plains.