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Natural abundance of 15 N in two cacao plantations with legume and non-legume shade trees

Natural abundance of 15 N in two cacao plantations with legume and non-legume shade trees Natural abundance of 15 N was sampled in young and mature leaves, branches, stem, and coarse roots of trees in a cacao ( Theobroma cacao ) plantation shaded by legume tree Inga edulis and scattered non-legume s , in a cacao plantation with mixed-species shade (legume Gliricidia sepium and several non-legumes), and in a tree hedgerow bordering the plantations in Guácimo, in the humid Caribbean lowlands of Costa Rica. The deviation of the sample 15 N proportion from that of atmosphere (δ 15 N) was similar in non-legumes Cordia alliodora , Posoqueria latifolia , Rollinia pittieri , and T. cacao . Deep-rooted Hieronyma alchorneoides had lower δ 15 N than other non-N 2 -fixers, which probably reflected uptake from a partially different soil N pool. Gliricidia sepium had low δ 15 N. Inga edulis had high δ 15 N in leaves and branches but low in stem and coarse roots. The percentage of N fixed from atmosphere out of total tree N (%N f ) in G. sepium varied 56–74%; N 2 fixation was more active in July (the rainiest season) than in March (the relatively dry season). The variation of δ 15 N between organs in I. edulis was probably associated to 15 N fractionation in leaves. Stem and coarse root δ 15 N was assumed to reflect the actual ratio of N 2 fixation to soil N uptake; stem-based estimates of %N f in I. edulis were 48–63%. Theobroma cacao below I. edulis had lower δ 15 N than T. cacao below mixed-species shade, which may indicate direct N transfer from I. edulis to T. cacao but results so far were inconclusive. Further research should address the 15 N fractionation in the studied species for improving the accuracy of the N transfer estimates. The δ 15 N appeared to vary according to ecophysiological characteristics of the trees. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Agroforestry Systems Springer Journals

Natural abundance of 15 N in two cacao plantations with legume and non-legume shade trees

Agroforestry Systems , Volume 76 (2) – Jun 1, 2009

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References (71)

Publisher
Springer Journals
Copyright
Copyright © 2009 by Springer Science+Business Media B.V.
Subject
Life Sciences; Agriculture; Forestry
ISSN
0167-4366
eISSN
1572-9680
DOI
10.1007/s10457-008-9160-3
Publisher site
See Article on Publisher Site

Abstract

Natural abundance of 15 N was sampled in young and mature leaves, branches, stem, and coarse roots of trees in a cacao ( Theobroma cacao ) plantation shaded by legume tree Inga edulis and scattered non-legume s , in a cacao plantation with mixed-species shade (legume Gliricidia sepium and several non-legumes), and in a tree hedgerow bordering the plantations in Guácimo, in the humid Caribbean lowlands of Costa Rica. The deviation of the sample 15 N proportion from that of atmosphere (δ 15 N) was similar in non-legumes Cordia alliodora , Posoqueria latifolia , Rollinia pittieri , and T. cacao . Deep-rooted Hieronyma alchorneoides had lower δ 15 N than other non-N 2 -fixers, which probably reflected uptake from a partially different soil N pool. Gliricidia sepium had low δ 15 N. Inga edulis had high δ 15 N in leaves and branches but low in stem and coarse roots. The percentage of N fixed from atmosphere out of total tree N (%N f ) in G. sepium varied 56–74%; N 2 fixation was more active in July (the rainiest season) than in March (the relatively dry season). The variation of δ 15 N between organs in I. edulis was probably associated to 15 N fractionation in leaves. Stem and coarse root δ 15 N was assumed to reflect the actual ratio of N 2 fixation to soil N uptake; stem-based estimates of %N f in I. edulis were 48–63%. Theobroma cacao below I. edulis had lower δ 15 N than T. cacao below mixed-species shade, which may indicate direct N transfer from I. edulis to T. cacao but results so far were inconclusive. Further research should address the 15 N fractionation in the studied species for improving the accuracy of the N transfer estimates. The δ 15 N appeared to vary according to ecophysiological characteristics of the trees.

Journal

Agroforestry SystemsSpringer Journals

Published: Jun 1, 2009

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