A Land-Value Tax (LVT) is a tax on the undeveloped value of land, as opposed to a property tax, which considers both the value of the land itself as well as any buildings.
A LVT is much simpler to implement than current income-based taxes because land is fixed in location, and the owners of land can be readily identified. A simpler taxation scheme should result in less tax evasion.
A LVT would not necessarily increase tax burden on farmers or the elderly. Farmers generally own land with lower valuation, and would be saving money that would have been consumed by income taxes. Similarly for the elderly: increased taxes on land should be offset by a decreased cost of living in other areas.
Lastly, a LVT should increase productivity because any added value would not be taxed.