Did you go through a intermediary and are planning to do a Sec 1031 exchange?
In that case, you will owe capital gain tax on gain on sale of the land. You will not be able to save tax though you are going to use the funds as a downpayment.
Normally if you do a sec 1031 exchange and buy a like kind property- meaning sell investment propert(land) and buy another investment property(not your personal residence) than you can defer tax on gain. But you need to go through an intermediary and hence you not qualify for this deferral,
Let me know if you have any question.
Please note: This advice is provided with the understanding that all the relevant facts have been provided by you. Any change in facts might affect the advice given and hence may not be relied on in such cases. Nothing contained in this reply was intended or written to be used, can be used by any taxpayer, or may be relied upon or used by any taxpayer for the purposes of avoiding penalties that may be imposed on the taxpayer under the Internal Revenue Code of 1986, as amended.