From the facts given in your Query, it appears-
1. you are actually using the land for agricultural purposes;
2. You actually continue to do cultivation in the plot.
3. In the Revenue records, you have changed its character, into non-agricultural land.
If it is shown in the revenue records and in the Sale Deed about to be executed & registered, as Non-Agricultural, the I.T.authorities will consider it as only agricultural land.
On the other hand, if you can forcefully prove as a fact that it has all along been, and is being used used only for agricultural purposes, andit has never been used for any non-agricultural purposes, you will get the benefit at least in the appellate stage.