1)
What is "Aval"?
1.
Radak: This is destruction of the land via eradication of its Peros. It will not give grain, wine and oil. If there are no farmers, there are no Peros. Aval is desolation, like "Al Ken Te'eval ha'Aretz" (Hoshe'a 4:3).
2.
Malbim: The verse depicts that wine, the 'son' of the vine, mourns over the lowliness of its father.
2)
Why did all happy people sigh?
1.
Radak: It is due to grain and wine. When they are plentiful, man is happy. When they are finished, man sighs.
2.
Malbim: Wine gladdens people's hearts, and it itself is mourning - it cannot gladden others!
