An Updated Isotopic Database of Fertilizers Used in Intensive Organic Farming: A Case Study on Protein Hydrolyzed Derivatives and Chelated Nutrients

• Published in: Horticulturae 2024-05, Vol.10 (5), p.523
• Main Authors: Muñoz-Redondo, José Manuel, Cuevas, Francisco Julián, Montenegro, José Carlos, Ordóñez-Díaz, José Luis, Moreno-Rojas, José Manuel
• Format: Article
• Language: English
• Subjects: agricultural practices; Agriculture; Agrochemicals; Analytical chemistry; Comparative analysis; Crops; Environmental aspects; Farmers; Fertilization; Fertilizers; Fingerprinting; Food; Food chains; Food supply; Isotope analysis; Isotopes; Micronutrients; Natural & organic foods; Niche markets; Nitrates; Nitrogen; Nitrogen isotopes; nitrogen stable isotopes; Nutrients; Organic farming; organic food authentication; Physiological aspects; Potassium; Proteins; Regulation; Retailing; Soil conditioners; soil fertility assessment; Sorghum; Stable isotopes; Supply chains; Variance analysis
• ISSN: 2311-7524; 2311-7524
• DOI: 10.3390/horticulturae10050523

The global demand for organic food products has rapidly increased over the last years, becoming an emerging niche market targeting the high-income segment. The higher retailing price for organic food products may increase the risk of fraudulent practices at the different stages of the food supply chain, and consequently, substantial control is needed. Currently, the authentication of organic food products, such as those of plant origin, remains a key challenge in analytical chemistry. While stable isotopes have emerged as a powerful tool for this purpose, most studies have focused on crops, missing the agricultural inputs used for fertilization that influence the isotopic values of the crops. In this study, we aimed to isotopically characterize commonly used fertilizers, soil conditioners, and micronutrient fertilizers in intensive organic agriculture in the largest organic production region in the world (Almería, Spain). Our goal was to clarify the limitations that nitrogen isotopic fingerprinting presents for the fertilizer input industry and to characterize the organic inputs. The conventional fertilizers analyzed in this study showed low δ15N values compared to their organic counterparts, except for some plant-based fertilizers, protein hydrolyzed fertilizers, and chelated nutrients. Both protein hydrolyzed fertilizers and micronutrient fertilizers presented a wide range of variability in their δ15N values, including some very low or even negative values, more similar to those of conventional fertilizers. The results of this study highlight the challenges of authenticating organic foods in agriculture when using nitrogen isotope analysis.