Tax on agriculture land

If it is rural agriculture land then it is exempted without any condition.
If its is not rural agri land then you can exempted from tax if you purchase new agri land within 2 years from the date of sale.

Agricultural land in Rural Area in India is not considered a capital asset. Therefore any gains from its sale are not taxable under the head Capital Gains.
For Capital Gain on sale of agriculture land other than rural agriculture land you can claim exemption under section 54B by purchase of another land for the agricultural purpose within a period of 2 years from the date of transfer of this land by individuals and HUF.