Is it permissible to take a portion of the debtor's land in exchange for settling the debt, and is this considered usury, especially given the registration costs? And should the land be valued at its current price or at its price a year and a half ago?

It is permissible to demand repayment of the loan at any time, even if it was deferred. It is also permissible to agree on taking a portion of the land at a price agreed upon by both parties, and the creditor bears the expenses of registering the land and similar costs. However, he is not obliged to accept a portion of the land as part of his debt.