As-Salaam Alaikum,

I want to know what is the ruling, if we own an open land and it does not generate any income is it zakathable or not

Where is this land?

It is only taxable by tge IRS if you rent it or sell it for a profit.

However, the local city, county or state may assess property taxes.

The OP is asking whether in Islam the donation of unused land is appropriate. The term "zakat" is the practice of charitable alms giving by Muslims.

fasahat: I suggest you post this question in the Islam section of Society and Culture forums here on AskMeHelpDesk.