Fossil energy usage for the production of baby leaves

Abstract

Abstract The cultivation of fresh-cut crops is shifting from traditional systems in open fields to soilless cropping systems in greenhouses. As a result, the energy requirements of crop cultivation are increasing rapidly. In this study, we analysed the economic and energetic performance of four baby leaf species (lettuce, rocket, spinach, and lamb’s lettuce) cultivated in a greenhouse under floating system. Four indicators were calculated, namely fossil energy input per unit area (EnIa: sum of the direct and indirect energy input per m2 per cycle), fossil energy input per unit product (EnIp: ratio of EnIa to fresh product mass per m2 per cycle), economic efficiency (EE: ratio of the gross income per m2 per cycle to the EnIa), and gross margin (GM: the difference between the gross income and the variable costs per m2 per cycle). In general, the EnIas obtained in this study were high (10.2–31.6 MJ m−2 cycle−1). Lettuce provided the lowest EnIp (3.0 MJ kg−1), and the highest EEs were attained under low nutrient conditions (0.81 and 0.48 € MJ−1 for lamb’s lettuce and lettuce, respectively). The GM of lettuce (on average 1.85 € m−2) and lamb’s lettuce (1.67 € m−2) were high. However, the consumption of fossil energy by baby leaves cultivated under soilless conditions in a greenhouse can be reduced by adopting precise nutrient management practices.