Inspired by this question.
There are certain halachos, such as Shmittah, which only apply in Eretz Yisrael. My question is: is it a din in the land of Eretz Yisrael or the airspace of Eretz Yisrael? A nafka minah would be a space farm that's locked in orbit directly above Eretz Yisrael. Would the farmers aboard have to observe Shmittah?
Shmita is a law of the land of Israel, not of the airspace above it.
A proof is that plants grown through hydroponics, i.e., with their roots outside of the soil, are not subject to the restrictions of Shmita (see e.g., here footnote 12 and there question 4).
Also, the biblical source for shmita speaks explicitly of the land
Six years you shall sow your land and gather in its yield; but in the seventh you shall let it rest and lie fallow. (Shemot 23:10-11)
When you enter the land that I assign to you, the land shall observe a sabbath of the Lord. Six years you may sow your field and six years you may prune your vineyard and gather in the yield. But in the seventh year the land shall have a sabbath of complete rest, a sabbath of the Lord: you shall not sow your field or prune your vineyard. You shall not reap the aftergrowth of your harvest or gather the grapes of your untrimmed vines; it shall be a year of complete rest for the land. (Vayikra 25:2ff)
