COMPARISON OF CONVENTIONAL, INTEGRATED AND ORGANIC POTATO PRODUCTION IN-FIELD EXPERIMENTS IN FINLAND

In 1987, a potato research project called ''Minimized use of chemical inputs in potato production'' was started in all five Scandinavian cou ntries. In this paper, the results of one field trial series carried o ut at the Potato Research Institute, Lammi, Finland, during the years 1987-90 are reported. The main plots in a split-plot designed trial se ries consisted of three cropping systems: conventional, integrated and organic. The subplots included three cultivars differing especially i n their late blight (Phythophtora infestans, (Mont.) de Bary) resistan ce: Bintje, Record and Matilda. Canopy measurements showed differences that can be attributed to different nitrogen supply in decreasing ord er from conventional to integrated to organic system. The trial sites were very heavily infested with potato scab, resulting in a very low p ercentage of I-class yield in susceptible cultivars Bintje and Matilda . Late blight was a serious problem in organically grown Bintje, as ex pected. Total yields in the integrated and organic systems were 10% an d 36% lower, respectively, than in the conventional system. There was an interaction between cropping system and cultivar in favour of Bintj e and the conventional system and Record in the organic system. The pe rcentage of I-class yield was lowest in the conventional system. Some of the quality characteristics were slightly improved in the integrate d and/or organic systems. Storage losses, caused mainly by tuber bligh t, were high in organically grown potatoes. There were no large differ ences in production costs between the cropping systems. The main deter minants of the unit production cost of potatoes were total yield and y ield of I-class potatoes. The average unit costs were 1.76 FIM kg(-1) in the conventional, 1.68 FIM kg(-1) in the integrated and 2.36 FIM kg (-1) in the organic system. Record showed the lowest unit production c osts in all systems - 1.33, 1.37 and 1.80 FIM kg(-1), respectively.