What is meant by the "original capital" by which commercial land is valued upon the passing of a year (hawl), is it the purchase price or its market value at that time?

If you buy land for trade, what matters is the hawl (one lunar year) of the money with which you bought it. So, if a hawl passes on it, the land must be zakat-able. If someone buys land with money that has already been held for eleven months, then he pays zakat on the land after one month.