landowners had mortgaged their land to pay for slaves it meant they would all lose their land once the slaves were free since few had money to pay off the debt.

Your observation is brilliant. It may turn out that there were "bankers" financing the purchase of slaves using land as collateral, and then when the slaves get freed (asset purchased with the "mortgage loan" to produce crops to sell to then pay the mortgage) many of the landowners probably couldn't make the payments on the loan they took out to buy the now free slaves; and they got foreclosed on (i.e. the bankers/slave traders that tricked them into taking out a loan, ended up with all the land).

You know this is a very good observation. It may turn out that there were "bankers" financing the purchase of slaves using land as collateral, and then when the slaves get freed (asset purchased with the "mortgage loan" to produce crops to sell to then pay the mortgage) many of the landowners probably couldn't make the payments on the loan they took out to buy the now free slaves; and they got foreclosed on (i.e. the bankers/slave traders that tricked them into taking out a loan, ended up with all the land).