I would not classify land as a commodity.
There are three conditions that must be met to call something a commodity. It must be:
1. Something bought or sold at a price which varies according to supply and demand. By this definition, it might be tempting to think of land as a commodity.
2. Something produced in volume according to the prevailing market price. If the price is high, then production increases. If the price drops, production is reduced accordingly. Land definitely does not fit here. Certainly the price and availability of land for purchase fluctuates according to price, but there is no production, and volume is never high.
3. It must be fungible: defined by the market as the same no matter where or by whom it was produced. A ton of soybeans is a ton of soybeans, whether they grew in Brazil or in America. A barrel of oil is a barrel of oil, whether it came out of the ground in Canada or Venezuela. In no way could land be considered fungible.