The trade-off between total harvestable production and concentration of the economically useful yield component: cane tonnage and sugar content James H. Cock * , Carlos A. Luna, Alberto Palma National Center for Sugar Cane Research, Cenican Äa, AA 91-38, Cali, Colombia Received 10 August 1999; accepted 11 May 2000 Abstract In several crop species, the harvested part of the crop (primary product) must be processed to extract the economically useful part (®nal product). The standard evaluation of new technology in these crops is normally based on the quantity of ®nal product per unit land area (®nal production), which is the product of primary production and the proportion of ®nal product that is extracted from the primary product (extracted product). This may be valid in terms of biological productivity, but in terms of commercial viability it is not satisfactory. Costs of harvest transport and initial processing of the primary product are normally more closely related to total primary production than to ®nal production. Identical values for ®nal production may be obtained through high primary production combined with low extracted product or vice versa. In the latter case, where primary production is less, the costs of harvest, transport and initial processing per unit ®nal product will be less. The standard evaluation, which gives equal weightage to primary production and extracted product, does not detect these differences in costs. A simple model is developed for sugar production from cane to make valid comparisons between the pro®tability of different treatments. The model can readily be adapted for other crops such as sugar beet, oil palm and cassava. # 2000 Published by Elsevier Science B.V. Keywords: Sugarcane; Selection; Processing; Economic evaluation; Model 1. Introduction Crop production today represents only one segment of the production process of any agricultural commod- ity. Increasingly, activities that were traditionally car- ried out by the farmer are managed by other entities (Le Heron, 1993). Processing of agricultural products so that they can be stored, transported conveniently over distances, and presented in forms appealing to consumers greatly extends the markets into which these products can be sold (Abbot, 1994). In crops such as wheat, the separation of production from processing has a long history. In the Ancient Roman Empire, the miller was already well established as a separate entity from the farmer and marks one of the ®rst examples of agricultural industrialization. Wheat and rice, which may be stored and transported rela- tively easily, are produced and sold through traditional markets with processing (milling) normally carried out near the site for ®nal consumption rather than in the proximity of the production center. The quality characteristics of the primary product (which is Field Crops Research 67 (2000) 257±262 * Corresponding author. E-mail address: jhcock@cenicana.org (J.H. Cock) 0378-4290/00/$ ± see front matter # 2000 Published by Elsevier Science B.V. PII:S0378-4290(00)00100-3