It is better to file the return.
A person earning Rs. 35 lacs per annum would be transacting in buying in immovable property, bulk mutual fund investments or share purchase, cash deposits of more than 10 lacs in a year in his bank account, etc., These transactions are captured in Annual Information Report.
If a person name is appearing in AIR & has not filed his return, IT Department will send a notice U/s 142(1), asking him to file the return.
My suggestion:
If the person's source of Income is only from agriculture, ask him to prepare a simple statement of assets & liabilities & P&L every year.
With that as a basis file the IT return every year even if the source of income is agriculture & it is exempt. Obviously a person earning Rs. 35 lacs will have some bank interest which he can disclose & pay tax on it every year.
By doing this records are clear & even the IT department comes for any survey or search. Returns filed as agri income would be of immense help. You could show that the source are already shared with IT Dept.