Seems like if the increase in the tax rate is hardly noticeable then it isn't going to lower land prices very much? You'd need a hefty tax to make desirable locations not worth spending money on.
Land prices decrease proportionally with the level of LVT implemented: 0% of today gives a 100% sales price; 25% LVT gives a 75% sales price; etc; 100% LVT as I propose gives a 0% sales price. Of course the prices increase in a particular transaction more than the exact amount if the buyer wants to live on the land for a long time, though.