The inputs used in crop production represent an energetic cost. Depending on the inputs and on the achieved yields, the conversion of the harvest into energy will determine the energetic efficiency of the system. Organic agriculture will fully meet the goal of environmental conservation only if its energetic sustainability is accomplished. The objectives of this study were to characterize the energetic balance of organic vegetable production and to analyze its energetic sustainability, compared to conventional vegetable crop production systems. Field data were collected from ten vegetable crop fields, from 1991 to 2000 in Domingos Martins, Espírito Santo State, Brazil. Data from the conventional system were obtained in the region. The technical coefficients of the systems were quantified and converted to an energy equivalent (kcal). The general average of the organic system was an input of 4,571,159 kcal ha-1 and an output of 12,696,712 kcal ha-1 at harvest, presenting an energetic balance of 2.78. This balance was similar to the conventional system (1,93). The components of the energetic inputs in the organic system were packaging (35,8%), organic compost (17,2%), irrigation (12,6%), seeds/seedlings (12,4%) and labor (11,0%), machinery (5,0%) and transport (4,5%). If package costs were removed, the energetic inputs on the organic system would be reduced to 2,930,113 kcal ha-1, greatly improving its energetic efficiency. Most of the crops could be considered sustainable regarding energy conversion, presenting balances higher than 1.00. The daily average energy yield in the organic system was 80,421 kcal ha-1 day-1 and was considered sustainable, higher than the minimum estimated calories need (58.064 kcal ha-1).
Organic agriculture; yield; crop systems; energetic balance
