Jeremiah expresses in more detail what he sees in the land, that is causing him such pain. For the land is full of adulterers.
Throughout his book, adultery is used to refer to both idol worship and to marital unfaithfulness. The two where inevitably intertwined in Judah since the worship of gods such as Baal, which was an act of supreme unfaithfulness to the Lord, often involved sexual immorality. This unfaithfulness has led to the Lord’s judgment, or curse
on Judah, so that the land mourns.
The Lord has brought drought and hardship in the land. The people of Judah had turned to Baal as the one who gives and secures blessing in the land, and so the true source of these blessings, the Lord of the covenant, withdraws them and replaces them with curses (Jeremiah 11:3, Jeremiah 11:8; Deuteronomy 28:15–68; Deuteronomy 29:19–21). This was not simply meant as punitive punishment, but as a sign that the people need to repent and return to the Lord.
10 For the land is full of adulterers; because of the curse the land mourns, and the pastures of the wilderness are dried up. Their course is evil, and their might is not right.