Evaluation of carbon, nitrogen, and oxygen isotope ratio measurement data for characterization of organically and conventionally cultivated spring barley (Hordeum vulgare L.) grain
¹University of Latvia, Faculty of Chemistry, Department of Analytical Chemistry, Jelgavas street 1, LV-1004 Riga, Latvia
²Institute of Agricultural Resources and Economics, Priekuli Research Centre, 2 Zinatnes street, LV-4126 Priekuli, Latvia
With the growing interest of public in the quality of their consumed food, organic produce has been steadily gaining an important place in everyday menus of our society. The growing demand has boosted organic farming and we have also seen the price difference between organic products and their conventional counterparts. It is important to the public to have security, that the food labelled ‘organic’ has really been grown according to the good practices of organic farming and that it has not received any chemical pesticides, herbicides, and synthetic fertilizers. Stable isotope ratios of crops from different crop management systems can help to answer these questions, as these values depend on the growing conditions, fertilizers used etc. In this study, 10 barley grain samples from conventional and organic crop management systems have been studied. Carbon, nitrogen and oxygen isotope ratios have been determined and the element content in the samples has been calculated. Student’s t-test has been performed to evaluate whether the differences between various parameters are significant. For potential clustering and discrimination of organic and conventional grains principal component analysis has been carried out. The PCA showed that no significant clustering can be observed, however the Student’s t-test for δ15N values confirmed that barley grown with green-manure fertilizers are significantly (p < 0.01) enriched with the heavier nitrogen isotope. Furthermore, it has been concluded that the total element content of carbon and nitrogen in barley grains does not correlate with the stable isotope ratios and cannot help with discriminating of these samples.