Skip Navigation


Tree Physiology Advance Access originally published online on March 20, 2009
Tree Physiology 2009 29(6):799-808; doi:10.1093/treephys/tpp017
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
29/6/799    most recent
tpp017v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Khamzina, A.
Right arrow Articles by Vlek, P. L.G.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Khamzina, A.
Right arrow Articles by Vlek, P. L.G.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org

Nitrogen fixation by Elaeagnus angustifolia in the reclamation of degraded croplands of Central Asia

Asia Khamzina1,2, John P.A. Lamers1 and Paul L.G. Vlek1

1 Center for Development Research (ZEF), Walter Flex Street 3, 53113 Bonn, Germany
2 Corresponding author (asia.khamzina{at}uni-bonn.de)


  Abstract

Extensive degradation of irrigated croplands, due to increasing soil salinity and depletion of soil nutrient stocks, is a major problem in Central Asia (CA), one of the largest irrigated areas in the world. To assess the potential for improving the productive capacity of degraded lands by afforestation, we examined N2 fixation of Elaeagnus angustifolia L. in mixed plantations with non-fixing Populus euphratica Oliv. and Ulmus pumila L. Fixation of N2 was quantified by the 15N natural abundance technique based on both foliar and whole-plant sampling during five consecutive growing seasons. Despite elevated root-zone soil salinity (6–10 dS m–1) and deficiency in plant-available P (4–15 mg kg–1), N2 fixation (%Ndfa) increased from an initial value of 20% to almost 100% over 5 years. Within each growing season, %Ndfa steadily increased and peaked in the fall. Annual N2 fixation, determined using foliar {delta}15N, initially averaged 0.02 Mg ha–1, peaked at 0.5 Mg ha–1 during the next 2 years and thereafter stabilized at 0.3 Mg ha–1. Estimates based on whole-plant {delta}15N were <10% lower than those based on foliar {delta}15N. The increase in plant-available soil N was significantly higher in E. angustifolia plots than in P. euphratica and U. pumila plots. Increases in the concentrations of organic C (19%), total N (21%) and plant-available P (74%) in the soil were significant irrespective of tree species. This improvement in soil fertility is further evidence that afforestation with mixed-species plantations can be a sustainable land use option for the degraded irrigated croplands in CA.

Keywords: afforestation, 15N natural abundance technique, P. euphratica, salinity, soil fertility, U. pumila, Uzbekistan

Received July 22, 2008; Accepted February 15, 2009


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.