Why will He call Chorev?
Radak: I decreed dryness on the land, which was dry, that its air will be dry, without moisture from the Tehom. This is the opposite of "umi'Tehom Rovetzes Tachas" (Devarim 33:13).
Malbim: The dryness will be via His calling, and not via Shamayim.
Why does it specify mountains?
Radak: There are mountains on which fruit trees sprout, and good herbs - "ume'Rosh Harerei Kedem umi'Meged Giv'os Olam" (Devarim 33:15).
Why does it specify Degen, Tirosh and Yitzhar?
Radak: Man's sustenance is primarily on them.
Malbim: Even though the land will produce them, they will be dry.
Why does it add "v'Al Asher Totzi Borei Peri ha'Adamah"?
Radak: This includes all other vegetation.
Why does it say "v'Al ha'Adam v'Al ha'Behemah"?
Radak: Dry air breeds illness among people and animals.
What do we learn from "v'Al Kol Yegi'a Kapayim"?
Radak citing Ibn Ezra: Those who irrigate from the well, they will not succeed; they toil in vain. The dry air will dry everything that they irrigate.
Malbim: Shamayim's curse will be on all man's toil.
