Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Early nitrogen fixation and utilization in Albizia lebbeck, Leucaena leucocephala, and Gliricidia sepium using nitrogen (15N) labelling.

Abstract

High nitrogen (N2)-fixing potential is a desirable characteristic for any candidate hedgerow tree,. Thus a study was conducted to evaluate Albizia lebbeck as a N2-fixing tree in comparison to Gliricidia sepium and Leucaena leucocephala, which are currently used in alley cropping. Nitrogen fixation and utilization were assessed in a screenhouse 4 months after planting seeds inoculated with Rhizobium, using the 15N dilution technique with Senna siamea (Cassia siamea) as the non N2-fixing reference. A. lebbeck accumulated significantly more N than L. leucocephala, but G. sepium was intermediate. This superiority in N yield was mainly due to its abundant nodule dry weight production which accounted for up to 10.8% of its total N. This was equivalent to 2.5- and 6-fold that of G. sepium and L. leucocephala nodules, respectively. A. lebbeck had a bigger but significantly (P≤0.05) lower number of nodules per plant than G. sepium, but it did not differ from L. leucocephala. A. lebbeck was the best N2 fixer with 44% Ndfa [nitrogen derived from atmosphere], equivalent to 533 mg N per plant. G. sepium followed with 28% Ndfa and L. leucocephala with 18% Ndfa corresponding to 321 and 191 mg N fixed, respectively. However, the relatively higher N2 fixation in A. lebbeck was not translated into higher N or dry matter yields. As A. lebbeck fixed more N, it depended less on soil N (49.8%) than did L. leucocephala (72.5% Ndfs [nitrogen derived from soil]) and G. sepium (63.9% Ndfs) and less on fertilizer N as well. Thus, A. lebbeck appears to be a potential hedgerow species for alley cropping purpose.