This study was conducted at the Horticulture nursery of Shark EI- Bohairate in
Esmailia Governorate during two successive seasons of 199912000 and 2000-2001., Pots seedlings of Acacia saligna 3 months old were fertilized monthly at the first
three months of planting with three different nitrogen sources namely: urea,
ammonium sulphate and ammonium nitrate at three rates of 0.5 , 1.0 and 1.5 gm N
for each I pot. The obtained results showed that different nitrogen fertilizers specially at low
level of 0.5 gm encouraged Rhizobium root nodules formation as atmospheric
nitrogen N2 fixation and produced a big size and heavy fresh and dry weight of
Rhizobium nodules more than unfertilized plants and as the appllcalion rate of
nitrogen fertilizers increased to 1.5 gm N. ,nodules formation decreased. Adding
ammonium sulphate as a nitrogen carrier at low level of 0.5 gm N. promoted much
more nodules formation than both forms of urea or ammonium nitrate. Nitrogen fertilizers sources enhanced all the vegetative growth parameters viz.
height growth Increment, stem diameter, fresh and dry weight of shoots than
unfertilized. Ammonium sulphate application at rate of 1 .. 0 gm N. resulted the best
growth height ,stem diameter and fresh weight of shoots followed by the form of
urea fertilizer and lastly coming ammonium nitrate, while ammonium nitrate produced
the heaviest dry weight of shoots followed by ammonium sulphate. Increasing the
levels of fertilizers to 1.5 gm N. reduced the growth. However it was rather than the
control. Ammonium sulphate fertilizer increased the ratio of fresh and dry weight of
shoots more than the two others and the form of ammonium nitrate reduced it.
Different rates of nitrogen application had no effected nearly on the ratio of fresh and
dry weight of shoots. Fertilizer efficiency of ammonium sulphate was greatly in fresh weight followed by urea then ammonium nitrate was the last. on the other hand ammonium nitrate
efficiency surpassed in dry weight production followed by ammonium sulphate and
lastly urea fertilizer. Chlorophyll a and b content in leaves did not affect due to
different nitrogen fertilizers sources. However the seedlings fertilized had excessive
values of chlorophyll a and b more than those unfertilized. Leave nitrogen content
increased positively due to different rates of fertilizers application where as the
application rate increased nitrogen content in leaves increased. Fertilized plants with
ammonium SUlphate at low level of 0.5 gm N. raised up the percentage of nitrogen in
leave more than the others carrier of nitrogen fertilizers, it may be due to that roots of
Acacia sa/igna formed Rhizobium nodules that fixed the atmospheric N2 more than
the other fertilizers It can be concluded from this study that there was synergetic
effect between Rhizobiumm formation and nitrogen fertilization in amending the
suitable nitrogenQus requirements for enhancing Acacia saligna growth specially in
sandy soil Therefore it can be recommended that ammonium sulphate as nitrogen fertilizer at
rate of 0.5 or 1.0 gm N. is suitable for Acacia sa/igna cultivated in sandy soil.