ECONOMIC PERFORMANCE OF PRE-CROPS IN A THREE-YEAR ROTATION PROGRAM FOR ORGANIC VEGETABLE PRODUCTION

Abstract

A four year experiment is being carried out, at Ege University Department of Horticulture, in which three different pre-crops are tested under an organic management system as compared to fallow. The aim of the experiment is to identify the most suitable rotation program for organic vegetable production in Turkey. Vicia sativa (common vetch), Brassica oleracea var. italica (broccoli), Vicia faba ‘Sevilla’ (faba bean) and fallow are tested as preceding (winter) crops. During the experiment carried out between 2007 and 2009, the main crops were tomato (2007), zucchini (2008) and pepper (2009). Broccoli represented the farmers’ choice as a winter vegetable. Vetch (incorporated) and faba bean (partially harvested and incorporated) were selected as legumes well adapted to the regional conditions. Soil fertility was maintained by incorporation of the crop residues at the end of both cycles and addition of organic-certified commercial compost (Bioaktif) and compost tea during the main cycle. All the management, including disease and pest management, was carried out according to the organic regulations valid in Turkey and the EU. During the production seasons, all variable costs and revenue, during both the pre-crop and main crop cycles, were recorded and gross margin calculated for each treatment. Economic analysis showed that broccoli as a pre-crop required the highest variable costs followed by faba bean, vetch and fallow, in all three years. Total revenue was the highest in plots where broccoli was the pre-crop. It is followed by faba bean plots mostly because higher yields were obtained in main crop plots following faba bean. The least profitable was fallow – main crop rotation. Broccoli plants also have some extra benefits like adding a high amount of biomass to soil and suppressing weed growth due to shading and allelopathic effects.