INFLUENCE OF TIMELINESS COSTS ON THE OPTI MAL LENGTH OF THE SUGAR-BEET HARVESTING PERIOD FROM THE VIEWPOINT OF COOPERATING FARMERS

The profitability of sugar-beet production is influenced by the costs of harvesting. Sugar-beet producers therefore should be concerned abou t the length of the harvesting period. Decisions on this matter requir e knowledge about the machinery costs and the loss in the revenue due to expanding the harvesting period (timeliness costs). To calculate th e timeliness costs the sugar-beet yield per hectare and the sugar cont ent of the beet according to the harvest time must be known. A feasibl e way to gather data concerning the sugar-beet yield per hectare and t he sugar content of the beet according to the harvesting date at reaso nable costs has been considered in collecting yield data from farmers operating beet harvesting machines in joint ownership. The yield data of three years were used to estimate functions which describe the deve lopment of sugar-beet yield and the sugar content respectively during the harvest season. The yield and sugar content functions were used to derive a revenue function which was the base to calculate the timelin ess costs for B-, C1- and C2-sugar-beets. The timeliness costs were in corporated in a cost model to determine the optimal length of the harv esting period for a six rows harvesting machine. The results show that the optimal length of season is determined mainly by the price of sug ar beet (B- or C-beet). The optimal length of the harvesting period ca lculated for the conditions assumed rs 41 days for B-beets and 45 days for C-beets respectively.