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Identifying N fertilizer regime and vegetable production system in tropical Brazil using 15 N natural abundance
Author(s) -
Inácio Caio T,
Urquiaga Segundo,
Chalk Phillip M,
Mata Maria Gabriela F,
Souza Paulo O
Publication year - 2015
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.7177
Subject(s) - lactuca , compost , organic farming , manure , agronomy , fertilizer , green manure , chicken manure , organic fertilizer , legume , environmental science , tropics , agriculture , biodegradable waste , biology , ecology
BACKGROUND This study was conducted in areas of vegetable production in tropical Brazil, with the objectives of (i) measuring the variation in δ 15 N in soils, organic N fertilizer sources and lettuce ( Lactuca sativa L.) from different farming systems, (ii) measuring whether plant δ 15 N can differentiate organic versus conventional lettuce and (iii) identifying the factors affecting lettuce δ 15 N . RESULTS Samples of soil, lettuce and organic inputs were taken from two organic, one conventional and one hydroponic farm. The two organic farms had different N‐sources with δ 15 N values ranging from 0.0 to +14.9‰ (e.g. leguminous green manure and animal manure compost, respectively), and differed significantly ( P < 0.05) in lettuce δ 15 N (+9.2 ± 1.1‰ and +14.3 ± 1.0‰). Conventional lettuce δ 15 N (+8.5 ± 2.7‰) differed from hydroponic lettuce δ 15 N (+4.5 ± 0.2‰) due to manure inputs. The N from leguminous green manure made a small contribution to the N nutrition of lettuce in the multi‐N‐source organic farm. CONCLUSION To differentiate organic versus conventional farms using δ 15 N the several subsets of mode of fertilization should be considered. Comparisons of δ 15 N of soil, organic inputs and lettuce allowed a qualitative analysis of the relative importance of different N inputs. © 2015 Society of Chemical Industry