[shiroiushi]

The place is a desert. Growing crops in a desert takes a lot of water, as you might imagine. A smarter thing to do is to not try to grow crops in a desert where it needs so much irrigation. The US has plenty of non-desert land for growing essential crops.

[chii]

desert weather is consistent(ly warm sunny). Irrigation being the missing factor means that you can have a nice long growing season, undisrupted by bad weather, or storms or any other number of unpredictable factors.