الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 157 |  |  |
| | | from | 157 | | |
Abstract
117
5- SUMMARY AND CONCLUSION
This study was carried out to investigate the effect of some chemical
transformations taking place in salt affected soils on production of dry
matter yield and uptake of N, P and K by corn plants grown on light and
heavy textured soils.
To fulfill these purposes, soil samples from different locations (El-
Dair and Moshtohor)were taken and chemically analyzed. These soils
varied widely in their physical and chemical proprties and were used in
salinization and sodicanon processes.
Both tested soils were salinized and sodicated according to the
following manner. (i) Representative portions of eaeh soil were treated
with progressing amounts of either NaCI or CaCl2 or both salts at
equtvalent ratios to give salinity levels approximately representative to the
standard salinity limits i.e 2, 4, 6 ,8, 12, and 16 dS/m.
To obtain of the non saline sadie soils from the original soil samples
(normal soils, of 0.75 and 1.05 ECl. soil samples were treated with
increasing amounts of NaOHyield increasing degrees of soil sodicity (ESP)
i.e 10, 12, 15, 20 and 25.
-----_.-- --------
118
Two biological experiments amied at monitoring the individual
effect of both salinity and sodtctty or the combined effect of both factors
on dry matter yield of corn plants and plant utilization of N, P and K.
The obtained results can be summarized in the following:
1- The electrical conductivity (EC)measurements of soil saturation extract
increased with increasing rate of added Nat or Ca””. This increase was
more pronounced in case of sandy soil as compared with the clay-textured
soil. The correlation coefficient ”r” values between added NaCIme/kg soil
and the electrical conductivity (EC) were 0.997***and 0.992*** in the
sandy and the clay soil respectively. This relationship could be
represented by the following equations:
EC = 1.3798 + 0.3618 NaCI (in case of sandy soil)
EC = 1.7496 + 0.1117 NaCl ( ” II 11 clay soil)
Concerning the relationship between added CaCl2 (me/kg soil) and the
electrical conductivity (ECL the correlation coefficient values were 0.998
and 0.997 for sandy and clay soils, respecttvtly. The equations describing
this relation could be written as follows:
EC= 1.3521 + 0.3302 CaC12 (in case of sandy soil)
EC””1.5443 + 0.1040 CaCl2 (” ” clay soil)
2- The exchangeable sodium percentage (FSP) increased with increasing
rate of added NaOH and inceasedmore sharphy in case of the sandy soil
as compared with the clay one.
119
The correlation coefficient ”r” between added NaOH me/kg soil and
the exchangeable sodium percentage (ESP) were 0.991 and 0.993 in the
sandy and the clay soils, respectively. This relationship could be
represented by the following equations:
ESP= 6.5406 + 1.0286 NaOH (in case of sandy soil)
ESP= 8.5747 + 0.2806 NaOH ( II
II II .clay soil)
3- The exchangeable sodium percentage (ESP) increased as a result of
increasIng sodium I calcium ratio of salts added to both sandy and clay
soils.
4- The exchangeable sodium percentage (ESP) was affected positively or
negatively with increasing soil salinity depending on the kind of salts
dominating in the soil solution.
5- Soluble cations (Na, Ca, and Mg) in both tested soils were increased with
increasing the electrical canductivity (EC) due to added NaCl or CaCl2
salts-
6- Deducing the ESPshowed the following equations:
ESP= 100(0.06153 + 0.02718 SARl
1+ (0.06153 + 0.02718 SAR)
(in case of sandy soil)
ESP= 100 (0.02042 + 0.02034 SAR)
1+ (0.02042 + 0.02034 SAR)
( in case of clay soil)
--- - - -- - -- ._--- ------
120
7- Dry matter yield of corn plants grown on sandy and clay soils showed a
drastically adverse effect due to salinity. Noteworthy mentioning that
while 50% yield of corn plants was achieved at Ee of 7.5 dS/m in the
sandy soil this level of yield was obtained at Ee of about 13.8 dS/m in the
heavy-textured soil.
8- The relative dry matter yield of corn plants grown on both light and
heavy-textured soils was gradually reduced with increasing the soil
sodtcity level. The obtained results show that while 50% yield of corn
plants was achieved at ESP 16.8 in case of light-textured soil, this level of
yield was achieved at ESPvalue of 23.40 in the heavy-textured soil.
9- Saline-sadie conditions depressed the dry matter yield of corn plants
grown on the light and heavy- textured soils as compared with control
treatment. The reduction in dry matter yield of corn plants under sadie
conditions amounted to about 21 and 44% in the heavy and light
textured soils, respectively.
10- Prediction of dry matter yield by using the different parameters of
salinity and sodicity show that:
a) In heavy-textured soil, correlation coefficient values for the
relationship between the soil salinity parameter i.e. (Ee) and the dry
matter yield was -0.99 in the saline soils of Ees 4 to 16, ESP 12 and-Q.98 in
saline-sadie soils of Ees 4 to 16 and of ESPs 15 and 18. This relatioship
could be represented by these equations.
D.M. yield = 4.389 ·0.163 EC (in saline soil)
. -------
121
a.M. yield = 4.881 - 0.150 EC (in saline -sodic soil)
b) In light - textured soil, the correlation coefficient ”r” between
values of EC and dry matter yield under saline and saline-sodic soils
conditions were -0.97 and -0.96, respectively. The equations describing
these relations could be written as follows:
a.M. yield := 3.835 - 0.222 EC (in saline soils)
” ”” = 3.409 - 0.208 EC (in saline - sadie soils)
c) In the heavy- textured soils. the values of correlation coefficient ”r”
between dry matter yield and ESP, SARand ESR variables were -0.993,
-0.993 and -0.996, respectively. The equations describing this relation
could be written as follows:
a.M. yield := 5.354 - 0.140 ESP
It ” := 5.077 - 0.234 SAR
II II := 5.088 - 9.799 ESR
d) In light-textured soils, the values of correlation coefficient II r’’
between dry matter yield and ESP, SAR and ESR variables were -
0.996, -0.995 and -0.992, respectively. The relation could be represented
by these equations:
D.M. yield = 4.043 - 0.138 ESP
” II = 3.692 - 0.263 SAR
II II = 3.651 - 9.095 ESR.
Such results may give further evidence to the importance of
developing other types of soil sodicity classification that take into
-- - -_.. --- ._--_ .. - _._,---- -- _. -- _. - -_. --- .- -- -_.~_.-
122
consideration the soil texture that control , Le., reduce or induce the soil
sodiclty hazard on growing plants.
11- N-cantent of corn plants grown on light textured- soil was sllghty
decreased with increasing soil salinity to ESPs·of12 and 15, while in heavy
textured soil, no clear or consistent effect on N content due to increasing
soil salinity up to EC16 dS/m was detected.
b) P-content of corn plants grown on light-textured soil increased
with increasing soil salinity up to EC16 dS/m
c) K-content of corn plants grown on sandy and clay soils was
decreased with increasing soil salinity or sodtctty.
12- The effect of soil sodtcity under non-saline conditions on N, P and K
contents of corn plants was as follow:
a) N-content of corn plants was slightly but gradually decreased
(from 4.7 to 4.2 %) with increasing soil sodiclty from ESP10 to 25. On
the other hand, an increasing tendency in N content of corn plants was
observed in case of heavy textured soil with increasing soil sodicity.
b) In sandy soil, no consistent trend due to the effect of increasing
soil sodicity on P-eontent in corn plants could be detected mean while a
slightly but gradually increasing trend was observed in case of the heavytextured
soil.
._.--- - -- _._------ ----
123
c} The K- content of corn plants grown on both light and heavy
textured soils was decreased with increasing the soil socncuv from ESP 10
up to 25.
13- The N, P and K uptake by corn plants was decreased with increasing
soil salinity and lor sodicity in both investigated soils. While the
reduction in N, P and K uptake by corn plants was more pronounced in
case’of the light-textured soil.