Tully Mill is situated geographically in the northern 'wet belt' and has a policy of encouragement of harvesting in the wet conditions. It has had ongoing problems with extraneous matter (E.M.) entering the factory, the main problem being dirt. Periodically, changes have been made to the process of evaluating the physical parameters of E.M., in an effort to encourage improved physical condition of cane supplied to the mill. The scheme in operation for the 1987 season had an inbuilt incentive bonus for the supply of clean cane, and also a penalty system which is applied to the different categories of E.M. It should be noted that the inclusion of 1% E.M. depresses the c.c.s. by 0.17 units, approximately. The scheme gives suppliers the opportunity to have penalties cancelled on categories other than dirt.