الفهرس 
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Abstract
This work was carried out to’investigate the
use of some synthetic materials (polyvinyl alcohol
”PVAn, Polyvinyl acetate ”PVAc” and Bitumen) as well
as natural materials (Shale, Farmyard manure ”FYM”
and Gypsum) as soil conditioners on three soils. The
soils were (a) a sandy soil from EI-Salheya, (b) a
sandy clay loam calcareous soil from El-Nobareya, and
(c) a sandy clay loam saline-sodic soil from Abeece.
Two greenhouse experiments were carried out on the
first two soils using barley as an indicator plant,
and a laboratory experiment was carried out on the
third soil. Treatments involved application of conditioners
in different manners: (a) each applied singly,
(b) each applied in combination with FYM (in the case
of the first two soils), and (c) each applied in combination
with gypsum (in the case of the third soil).
Shale was used only with the first soil, and gypsum
was used only with the third one.
applications of conditioners were
Three rates of
used. They
were as follows: PVA (or PVAc): 0.67%, 1.00\ and 1.33%;
Bitumen: 1.00\, 1.50% and 2.00%: FYM : 1.33\, 2.00% and
2.67% and shale 4.67%, 7.00% and 9.33%.
Results with the first two soils indicated that
all conditioners showed improvement in soil properties,
as they decreased bulk density and increased soil aggregation.
aggregation index ”AI”. mean weight diameter
”MWD”. Wind erosion index ”WEI”, pore size distribution~
soi 1 water retention and avail abl e moi sture particularly
with increasing their rates of application.
As an example of effect on the sandy soil, during
its 45 days following experiments, the treated
conditioned soil showed 48%, 46%, 37%, 36% and 30%
total aggregates in the cases of Bitumen. PVAc, shale,
PVA and FYM, respectively (average of three rates),
while untreated soil had total aggregates of 14%.
Total
porosity values for the same soil during the same period
were 38%, 47%, 46%, 45%. 44% and 42% for control, Bitumen,
PVAc, FYM, PVA and shale treatments, respectively.
Bulk densities of the treatments were 1.62,
1 •32, 1. 42, 1. 46, 1. 47 and 1. 51 for the con tr 0 l, Bitumen,
PVAc, PVA, FYM and shale, respectively.
In the sandy soil, treatments receiving both FYM
and shale led to a slight increase in electric conductivity
”EC” of the soil extract~ apparently due to the
improved conditions for plant growth which led to more
water being used during the season, as well as salt
contents of the materials.
Also, the cation exchange
capacity increased from 1.54 meq/l00 g for the control
to 1.69, 1.64 and 1.63 for PVA, PVAc, and Bitumen, respectively
as compared with 5.41 and 4.27 for shale
and FYM, which could be due to the colloidal nature
of the last two materials.
The other heavier soil showed similar results.
This soil being rather saline (EC = 6.16 mmhos/cm/2SoC),
all treatments and the control showed at the end of the
experiment~values of EC smaller than the initial EC,
due to leaching.
Compared with the control, FYM in
particular showed higher EC values which may have been
due to its relativelY high content of salts.
Time duration led to a decrease in the improvements
on physical and chemical properties already
occurred following application, particularly with FYM,
apparently due to the decay of the conditioning materials.
Treatments receiving shale showed the least change with
time reflecting its stability.
Application of conditioners caused a delay and
a decrease in seed germination possibly due to impervious
layers formed around seeds, but eventually plant
growth as well as its uptake of N, P and K were increased.
Treatments receiving soil conditioners in
combination with FYM also showed patterns of response
similar to those where conditioners were applied
singly; however the magnitude of the response was
greater.
Time duration, also led to a decrease in the
improvements and the extent was greater in this respect
than when conditioners were applied singly.
Results of the laboratory experiment (the third
soil) showed improvement of soil physical properties by
application of soil conditioners.
Salinity and exchangeab1e
sodium percentage ”ESP” were decreased by application
of conditioners.
EC waS originally 7.88 mmhos/
cm/250C, it decreased to reach a value of nearly one
sixth that of the original. ESP was 19.20\ originally;
it decreased to as low as 4.30% by treatments
giving an indication of a decrease in EC of all treatments
during the course of experiment.
conditioners
applied in combination with gypsum were more effective
in improving soil physical and chemical properties than
when applied singly.