الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
Egyptian economy depends to a great extend on agriculture, a
condition which seems to continue for many years to come. The rapidly
growing population and the improvement of the standard of living face
agriculture with continuos demand for high production. Thus the
prominent aim of its policy is to increase the land production through
better land and water use; improvement of agricultural technique and
bring new land areas under cultivation. Looking to the future of
stressing water demands, it is quite obvious, that very efficient use of
the available water sources and looking for new water resources are a
must.
The main task of present work is to study the effect of using
drainage water in irrigation and the impact of its application on some
soil properties, plant growth, water use effeiciency and heavy metal
contents of the growing plants.
Germination experiment was conducted under the laboratory
conditions to test the germination of different crops such as tomato,
squash, beans, cotton, com and wheat, the mixing ratios ofDW:CW
used in germination were 0:100, 25:75, 50:50 and 75:25.
Greenhouse experiment was conducted in Soils & Water Use
Dept.NRC, Dokki, Giza, Egypt. Wheat (triticum sativum L.cv. Sakha th
69) was planted in Dec.17th 1998 and harvested in May 3 1999. While
com (zea maize L.cv. hybrid 310) were planted in June e ’ 1999, and
harvested in Aug. 9 th 1999. NPK fertilizers were added at the
recommended doses. Both plants were irrigated using the (DW:CW)
mixing ratios (0:100, 25:75,50:50; 75:25, and 100:0) twice a week.
Loamy clay soil was selected at Moshtohor Village, Toukh
District, Qulubia Governorate, Egypt. The experiment is located near
EI-Qulubia main drain.
Field experiment was divided in to fifteen plots each (108 m 2)
and one meter apart to avoid irrigation treatment effects. The
experiments were in randomized completely block design, factorial
analysis. Winter crop (wheat) was planted in Nov. 26th 1998 and
harvested in May 7th 1999. Corn as a summer crop was planted in
May 20th 1999 and harvested in Sep. 2nd 1999. NPK fertilizers were
added as recommended doses for both crops. Plants were irrigated
alternatively every 21 and 12 days in winter ander summer,
respectively using the following DW/GW treatments: O/all, 1/3, 212, 3/1
and all/O.
The obtained data could be summarized in the following:
• Germination percent decreased with increasing drainage water in
the ratio 75: 25 (DW: CW) for sensitive crops.
• Increasing DW in the DW:CW mixing ratios used for irrigation
increased plant weight and weight of both grains and straw / plant.
It also increased both CU and WUE. The highest grains yield per plant
and highest seed index were obtained in the DW:CW mixing ratio
50:50, i.e. improved grains yield and their quality.
• For wheat plant, increasing the number of consecutive irrigation
using DW increased wheat growth and WUE and it also decreased CU.
The optimum irrigation treatment for weight of plants, spikes and
grains (ton/fed) and WUE was 212. Since it did not differ significantly
at the 5% level from aiI/Otreatment. On the other hand the minimum
values of the parameters under study were obtained in treatment 1/3 and
sometimes in 3/1 one.
• For corn plant, increasing the number of consecutive irrigation
using DW increased both grain yield and WUE and decreased the CU.
• The data revealed that increasing the drainage water (DW) in the
(DW:CW) water mixture used for irrigation from zero DW( 100% CW)
to 100% DW (0% CW) increased the aggregation percent from 9.03 to
17.14 % and the mean weight diameter from 0.01 to 0.13 mm according
to the irrigation treatment and aggregate size under study.
• The maximum aggregation percent was achieved in the DW:CW
mixing ratio 50:50 regardless of the aggregate size. The difference in
the percentage of aggregates (8.0 - 0.1 mm) between the DW:CW
mixing ratio 0:100 and any ofthe other ratio were significant at the 5%
level.
• The results reveal that the irrigation treatment DW/GW (2/2) led
to the maximum aggregate percent (10.61 %) and maximum aggregate
MWD(0.014) for aggregate size of 0.25 - 0.10 mm (fine sand fraction).
• The irrigation treatment DW/GW (2/2) in the alternative
irrigation and the mixing ratio DW:CW 50:50 improved soil
aggregation.
• Using drainage water in irrigation either mixed with canal water
or alternatively with ground water reduced soil HC. The following
points has to be stressed in using drainage water in irrigation either
mixed with canal water or alternatively with ground water:
i) increasing the amount of drainage water in the two irrigation
techniques reduced soil hydraulic conductivity, ii) Although, soil
hydraulic conductivity is still classified as moderate, caution must
be taken to avoid the DROP in soil hydraulic conductivity of the
clay soils and subsequently in the efficiency of their drainage
system, and iii) soluble source of Ca has to be added either to the
soil or to the irrigation water, otherwise, drainage water would be
used in sandy soil, wherever and whenever its transportation is
economically visible.
• Water intake into the soil took a trend similar to that of both
aggregation percent and the mean weight diameter of the aggregation.
• Using drainage and canal water mixing ratio (50:50) in irrigation
increased soil salinity by 33.7 % as compared with control soil (CW
only). Irrigation with drainage water alone increased the salt
accumulation in the soil by 92.2 % relative to the control after wheat
(greenhouse experiment).
• After corn, the accumulation of salt in the studied soil was
observed. At DW:CW mixing ratio 50:50, soil salinity increased by
about 27 % and gradually increased at DW:CW mixing ratio of 100:0 to
37.7 % relative to the control.
• The pH values of the investigated soil increased from 7.47 to
8.50 (greenhouse experiment).
• It was noticed that using drainage water increase the soluble
cations as follows: Na > Ca ” > Mg at a ratio 50:50 after wheat and
corn in greenhouse experiment. The same results were obtained in the
field experiment.
• Heavy metals contents increased with different rate in plant
organs and soil, but it still within the tolerable limits.
• The fresh Nile water is consider safe for irrigation, however, the
drainage one has ability to cause moderate salinity and severe sodicity
problems. Under the poor drainage condition and hot and dry climate,
the salinity and sodicity were formed due to the application of either
good or poor quality irrigation water.
It can be concluded also, that the irrigated agriculture can
not be sustained without adequate leaching to prevent excessive
salination of the soil. Furthermore, national programs are needed to
isolate industrial sources of trace elements from the sewage system
where the sewage effluents are dumped into the agricultural drainage
system. Meanwhile the sewage effluent should be treated enough to
meet the required national standard before its damping, so it should be
proceeded and used efficiency as a source of plant nutrition in the
greatest abundance relative to crop / or soil requirement. Such program
would improve the environmental quality, decreases requirement for
commercial fertilizers and improve animal and human health.