(a) Subject to any contractual provision to the contrary and based upon whatever market the contracting parties agree to:
(1) The discount rates for foreign material and moisture content may not be higher than the discount rates that prevail on the day the contract is formed;
(2) The test weight rates may not be higher than the test weight rates that prevail on the day the contract is formed.
(b) This section applies to any contract for sale of grain entered into in this State provided the date of delivery is less than 1 year after the date the contract is formed.