Comparison of Effects of Chemical and Food Waste-Derived Fertilizers on the Growth and Nutrient Content of Lettuce (<i>Lactuca sativa</i> L.)

Abstract

The current high rate of food waste production, concomitant with the global increase in population and food demand, has adverse effects on environmental and socio-economic conditions. However, food waste has been shown to be an efficient and safe source of fertilizer in agriculture practice. Moreover, minimizing the application of chemical fertilizers is a goal of sustainable agriculture. Considering these facts, we aimed to compare the effect of chemical fertilizer (CF-3,8 g·pot−1) and different doses of mixed food waste-derived fertilizer (MF-10.6 g·pot−1), two-fold MF (MF × 2), four-fold MF (MF × 4), and six-fold MF (MF × 6) in a popular salad crop, Lactuca sativa (lettuce). Our results showed the growth rates of lettuce plants receiving CF, MF, and MF×2 applications were essentially the same; however, plant biomass significantly dropped with MF × 6 treatment. The CF, MF, and MF × 2 treatments enhanced the chlorophyll content, chlorophyll fluorescence, and photosynthetic rate of the plants and improved transpiration efficiency and stomatal conductance. With respect to mineral elements, the K+ content was significantly enhanced with MF × 2 and MF × 4 treatment, whereas MF × 6-treated plants showed lower concentrations of Ca, P, Mg, and K+ as well as higher Na+ concentration. Biochemical analysis showed the elevation of abscisic acid level with increasing dose of MF, except in the MF × 6 treatment. The level of super oxide dismutase (SOD) dropped with CF treatment, was unchanged with MF, and significantly increased in MF×2 and MF × 4 treated plants. Subsequently, higher flavonoid content was observed in MF×2 and MF×4 plants. The current results demonstrate the potential of food waste as a source of organic fertilizer and a significant substitute for chemical fertilizer in the conventional agricultural practice driven by high production cost and environmental pollution.

Keywords

• food
• chemical fertilizer
• environment
• mineral
• salt
• sustainable agriculture