No organization hereby authorized shall, without the approval of the Federal Farm Loan Board, discount any note or other obligation, upon which the original borrower has been charged a rate of interest exceeding by more than one and one-half percent per annum the discount rate of said Federal Intermediate Credit Bank at the time the loan was made. But any organization hereby authorized may charge the original borrower a rate of interest equal to the current discount rate of said Federal Intermediate Credit Bank plus such excess as may be approved by the Federal Farm Loan Board, and if such rate shall amount to more than eight percent per annum the same shall not invite any penalty, nor constitute a violation of any interest or usury law of this state.