Pls help: tax on agriculture land sale

Hello,

Could anyone please help me with my confusion.

I have some ancestral agriculture land in Punjab. The market value of land is approx 16 lakh per acre but the gov. rate is 8 lakh rupees only. People there goes for registry at the gov. rate only not the actual sale price of land. 

My plans are to sell the land and buy properties in cities.

So, does the rest of the 8 lac rupees in 16 lac comes in black money?

Thanks,

Aditya