Irigoyen, I. and Muro, J. and Lasa, B. and Storino, F. and Domeno, I. and Jauregui, I. and Azpilikueta, M. and Aparicio-Tejo, P. M. (2012) 15N natural abundance of barley and spinach fertilized with legume residues, compost or inorganic nitrogen. Acta Horticulturae, 938. pp. 277-282. ISSN 0567-7572
Full text not available from this repository.Abstract
Agencies for organic farming certification require the development of control techniques to control fertilisation management. Natural N-15 abundance, expressed as delta N-15, is considered as an integrated descriptor of the N historical cycle of an agro-system, thus isotopic techniques has been proposed to verify the organic or inorganic nature of N fertilizers applied to crops. Therefore delta N-15 of organic and inorganic fertilizer should be consistently different, and plant delta N-15 should reflect delta N-15 of fertilizers employed. In this work, the delta N-15 of spinach (Spinacia oleracea L.) and barley (Hordeum vulgare) cultivated with three different types of fertilizers (inorganic fertilizer, composted sheep manure, and legume residues) at three N rates (low, medium and high) were compared in a pot trial performed in a greenhouse. Results showed that with compost the delta N-15 was always higher than 5.5 parts per thousand in barley and than 8 parts per thousand in spinach. However, with inorganic fertilizer or legume residues the delta N-15 was lower than 5 parts per thousand in barley and than 6 parts per thousand in spinach. Besides this, delta N-15 increased strongly with the rate of compost applied, reaching values higher than 13 parts per thousand. It could be concluded that isotopic techniques could be useful in verifying if barley or spinach have been fertilized with compost. However, these techniques do not seem to differentiate between crops grown with inorganic fertilizers or with legume residues. Therefore, its applicability to be used as control technique by agencies for organic farming certification is limited.