1)
Why does it say "la'Aretz
1.
Ohr ha'Chayim: The food will firstly sustain Egypt. After it suffices for Egypt, it will save the land (i.e. also other lands) from extinction.
2.
Malbim: The food gathered in the cities will be for Egypt itself. The fifth of grain gathered in the capitol will be to sell to other lands, which will bring great wealth to the royal storehouse.
