Regarding sales of agriculture land

Sir, I am an agriculturust and purchase the agri land for Rs 4.00 lac in the asstt year 2012 _2013 and the said agri land sold in asstt year 2013_14 for Rs 20 lac but according to the revenue value the registration made for Rs 4.50 lac, whereas the sale price settle for Rs 20 lac. The applicant pay the revenue on the revenue price settle by the revenue department . But the applicant has been deposited Rs 20 lac in his saving bank account. Sir this agri land does not fall in any municipal area and urban estate. Sir now the applicant has been receive a notice to show the source of the cash deposit. Sir I want to know that I am liable to pay any kinds of tax i. e capital gains on sale of this agri land.