Multielement isotope ratios of vegetables from integrated and organic production

In this paper we discuss the use of isotope ratios as indicators of organic production. Few studies have investigated the influence of plant nutrition on the isotopie signatures of plants. As plant nutrition is often significantly different between integrated and organic production systems the isotope ratios in the plants may reflect this. Plant samples from a 2-year field-experiment were analyzed for ¹⁵N, ¹³C and ³⁴S content of the bulk-material and ¹⁸O-content of the leaf water. In this experiment cabbages (Brassica oleracea v. capitata f. alba cv. Roily), onions (Allium cepa cv. Alisa Craig), lettuces (Lactuca sativa v. capitata cv. Ponchito) and Chinese cabbage (Brassica pekinesis cv. Parkin) were cultivated according to good agricultural practices for integrated and organic production. No differences in the δ³⁴C and δ¹⁸O values of the plants grown under the two production systems were observed. The organically produced vegetables were significantly enriched in ¹⁵N and depleted in ¹³C compared to those grown under the integrated system.