Background and methodology:
Few studies have investigated the influence of plant nutrition on the isotopic signatures of plants. Because plant nutrition often is significantly different between integrated and organic production systems, the isotope ratios in the plants may reflect this. Researchers analyzed bulk material and leaf water from plant samples of a two-year field experiment. In this experiment, cabbages (Brassica oleracea v. capitata f. alba cv. Rolly), onions (Allium cepa cv. Alisa Craig), lettuce (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.
Findings:
The results of this study show that there are differences in nitrogen and carbon isotope signatures between vegetables grown under organically and integrated-production systems. The organically produced vegetables were significantly enriched in nitrogen and depleted in carbon isotope signatures compared to those grown under the integrated system. Fertilization and cultivation practices had no effect on the sulfur and oxygen isotope ratios in plant tissue. The accumulation of nitrogen by plants that were not given nitrogen fertilizer means that differences in the nitrogen values of the fertilized plants may be smaller than the difference of the isotopic composition of the fertilizers.
Reference:
Georgi, M., Voerkelius, S., Rossmann, A., Grassmann, J., & Schnitzler, W.H. (2005). Multielement isotope ratios of vegetables from integrated and organic production. Plant and Soil, 275(1/2), 93-100. Available on-line at: http://dx.doi.org/10.1007/s11104-005-0258-3