FLPMA Demands Fair Market Value for Use of Public Lands

Sec 102 (a) 9;
"The United States receive fair market value of the use of the public lands and their resources unless otherwise provided for by statute."

Wondering where is the statute, if any, that says grazings fees are to be kept below fair market value?

Full text of FLPMA; http://www.blm.gov/flpma/FLPMA.pdf