Land is not a commodity: it is a factor of production or source of value. Location, and the capital invested in it. has a use value over time, aka rental value. The fact is that two thirds of 'fiat' money in existence is people-based (the loan is to the owner, not the land) and is backed by a claim over land - a mortgage.

If you think about it, the sale price of land & buildings which backs mortgages is effectively the net present value of future rentals.

If you have a state issuing currency then this currency is redeemable in payment for taxes.  The problem is that very little tax is actually levied on unearned income from land, and most of it is levied on earned income from labour.

But if one were to have land-based currency this would not be through the ability to redeem it against ownership of land but rather against the rental value of land. This is actually quite straightforward to do, by having land held by a custodian (which could be the existing owner) and enabling the issue of units redeemable in payment for (say) £1.00's worth of rental value.

If the Unit is issued at 80p the result is a return of 25% upon redemption: but what determines the rate of return is the time of redemption, and this may depend on many things.

The broadening of redemption may be achieved through paying dividends of units within communities; enabling occupiers to pay rentals in 'sweat equity', and so on.

Also, note that land-based currency would be just one - geographically fungible  - currency. Others could include currencies backed by energy, and by Labour.

"The future is already here -- it's just not very evenly distributed" William Gibson