B. Lal et S. Khanna, LONG-TERM FIELD-STUDY SHOWS INCREASED BIOMASS PRODUCTION IN TREE LEGUMES INOCULATED WITH RHIZOBIUM, Plant and soil, 184(1), 1996, pp. 111-116
Nodulation potential, nitrogen fixation efficiency (nitrogenase activi
ty) and biomass yield response of Leucaena leucocephala and Acacia nil
otica to inoculation with 6 selected fast growing Rhizobium strains wa
s explored in long-term (5 year) field trials. All the strains formed
nodules and fixed nitrogen in L. leucocephala and A. nilotica. Seasona
l effects on nitrogenase activity was observed and in winter (ambient
temperature about 20 degrees C), nitrogenase activity could not be det
ected. However, with the onset of spring and a rise in temperature, fr
esh nodulation (renodulation) by all the inoculant rhizobial strains w
as observed in both the tree legumes. In L. leucocephala, maximum reno
dulation was exhibited by strain Al while in A. nilotica, strain AB3 f
ormed the maximum renodulation 24 months after transplantation. Dry ma
tter yield of all the inoculated plants demonstrated a significant inc
rease over that of the uninoculated plants at the end of five years af
ter transplanting. In L. leucocephala, strain NGR8 gave the maximum re
sponse (45% more dry matter yield) in dry matter production while in A
. nilotica, strain USDA 3325 showed a 25% increase in total dry matter
yield five years after transplantation.