The price at which the guarantee is set is determined by reverse auctions, in which landowners submit bids for the price they want to receive, with the lowest bid winning.
Caiff pris y warant ei bennu drwy ocsiynau lleihau pris, lle bydd perchenogion tir yn cyflwyno cynigion am y pris yr hoffent ei gael, gyda'r cynnig isaf yn fuddugol.