Effect of Organic and Synthetic Fertilizers on Nitrate, Nitrite, and Vitamin C Levels in Leafy Vegetables and Herbs

This study investigated the accumulation of nitrate and nitrite, as well as the vitamin C content, in various leafy vegetables, including amaranth greens, katuk, morning glory, squash leaves, vine spinach, leaf lettuce, romaine lettuce, Vietnamese basil, Vietnamese perilla, komatsuna, leeks, and spinach, grown with either organic or synthetic fertilizers. The findings indicate that the type of fertilizer significantly influences nitrate accumulation and vitamin C content in these vegetables. Organic fertilizers were found to reduce nitrate levels and increase vitamin C content in amaranth greens, katuk, morning glory, squash leaves, vine spinach, leaf lettuce, Vietnamese basil, Vietnamese perilla, and spinach compared to the results for synthetic fertilizers. However, high nitrate concentrations in leaf lettuce, komatsuna, and spinach pose potential health risks. The study also identified elevated nitrate levels in vegetables that are not currently regulated. Furthermore, more than half of the samples contained nitrite, for which no maximum permissible level has been established. These findings underscore the importance of organic vegetable cultivation in enhancing both human health and environmental sustainability.