02038naa a2200241 a 450000100080000000500110000800800410001902400270006010000180008724501390010526000090024452012750025365000160152865000170154465300300156165300270159165300170161870000170163570000170165270000190166970000170168877300910170520310602016-02-02       2015    bl uuuu     u00u1 u    #d7 a10.1002/jsfa.71772DOI1 aINACIO, C. T.  aIdentifying N fertilizer regime and vegetable production system in tropical Brazil using 15N natural abundance.h[electronic resource]  c2015  aThis study was conducted in areas of vegetable production in tropical Brazil,with the objectives of (i)measuring the variation in ??15 N in soils, organic N fertilizer sources and lettuce (Lactuca sativa L.) from different farming systems, (ii) measuring whether plant ??15 N can differentiate organic versus conventional lettuce and (iii) identifying the factors affecting lettuce ??15 N. Samples of soil, lettuce and organic inputs were taken from two organic, one conventional and one hydroponic farm. The two organic farms haddifferentN-sources with ??15 Nvalues ranging from0.0 to+14.9‰(e.g. leguminous greenmanure and animal manure compost, respectively), and differed significantly (P &lt 0.05) in lettuce ??15 N (+9.2±1.1‰ and +14.3±1.0‰). Conventional lettuce ??15 N (+8.5±2.7‰) differed from hydroponic lettuce ??15 N (+4.5±0.2‰) due to manure inputs. The N from leguminous green manuremade a small contribution to the N nutrition of lettuce in the multi-N-source organic farm. To differentiate organic versus conventional farms using ??15 N the several subsets ofmode of fertilization should be considered. Comparisons of ??15 N of soil, organic inputs and lettuce allowed a qualitative analysis of the relative importance of different N inputs.  aFertilizers  aFertilizante  aFertilizante convencional  aFertilizante orgânico  aHidropônico1 aURQUIAGA, S.1 aCHALK, P. M.1 aMATA, M. G. F.1 aSOUZA, P. O.  tJournal of the Science of Food and Agriculturegv. 95, n. 15, p. 3025-3032, Dec. 2015.