الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
This research aims at study the effect of both slow release
(ureaformaldehyde) and soluble nitrogen fertilizers ( urea) application in
presence or absence of polyacrylamide on release rate of different
nitrogen forms, through incubation experiment. Also studying the effect
of ureaformaldehyde and urea with or without polyacrylamide
application on N-uptake by sorghum and barley plants growing on either
calcareous or sandy soil and its reflection on growth and uptake of P &
K by plants grown on both soils under investigation through a
greenhouse experiment.
1-lncubation experiment:-
Two soils namely calcareous and sandy soils were used in this
experiment, 1000 ppm. (N) was added to each pots as
ureaformaldehyde and urea. The pots were divided into two sets. The
first set pots were treated with PAM at rate of 0.1% and the second one
was left untreated. Pots were incubated at 33 OC-1at different periods
namely:- 3, 7, 28, 84, 168, 252 and 336 days.
Sub-samples were tested to estimate their content of urea,
ammonium, nitrate and nitrite at the above mentioned times.
The obtained results can be summarized as follow :-
1- Organic nitrogen (urea-N) :-
Urea was quickly decomposed during or through at the first period
of incubation, the degradation of urea in calcareous soil was higher than
sandy soil. However ureaformaldehyde slowly decomposed to urea-N at
the long of experiment. Values of released urea-N were lower at the first
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sample, 28 days from starting. After 84 days the experiment different N
forms decreased gradually till the end of experiment. Data indicated that
urea-N released in from ureaformaldehyde in calcareous was higher
than that sandy soil.
Urea-N released from ureaformaldehyde + PAM was higher as
compared with ureaformaldehyde applied alone specially at the end of
different incubation period.
2.lnorganic nitrogen :-
Ammonium-N
Soil content of ammonium-N in the beginning of experiment (i. eat 3
days after beginning) was higher when urea was applied with or without
PAM to calcareous and sand soils as compared with ureaformaldehyde
in presence or absence of PAM and it was gradually decreased after the
beginning 7 days till the end of experiment.