Organic crop production is a system requirement covering many aspects of its production. One main feature, which distinguishes organic from conventional production is the prohibition on the use of synthetic fertilisers, which are produced from atmospheric nitrogen by the Haber process, and the resulting nitrate is high in 18O and low in 15N. Isotopic measurement of nitrate extracted from plant foods can indicate which fertilisation system has been used. This requires a bacterial reduction, which is costly and can only be done by specialised laboratories. Research scientists at IAEA have developed a rapid, low-cost method to measure N and O isotope ratios using a one-step Ti(III) reduction to convert the nitrate to N2O gas for headspace isotope analysis using IRMA (isotope-ratio mass spectrometry). The new method was developed and tested using organic and conventionally grown Spanish strawberries, where the extractable nitrate N and O isotope ratios and the chemical composition were measured followed by chemometric analysis, and which revealed that the δ18O of nitrate along with δ15N and Ca2+ fully differentiated organic from conventional strawberry production.
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