الفهرس 
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Abstract
Egypt is fronting great challenges owing to its inadequate water resources represented in its settled share of the Nile water as 55.5 billion m3/year. Irrigated agriculture is the principal consumer of freshwater in Egypt, agricultural activities in Egypt munches about 85% of the Nile water budget. What makes matters even worse, surface irrigation is the dominant irrigation system in the old Nile Valley and Delta lands with application efficiency less than 50% triggering large losses of this valuable resource to groundwater. Extensive agricultural areas in Egypt have arid and semi-arid conditions and severe problems of salinization because of irrigation with low water quality along with poor drainage infrastructures, low soil fertility or nutrients availability. In this regard, irrigation with saline water is compelling farmers of arid areas to devise innovative technologies to reserve crop yield and quality while adopting to conserve natural resources. These problems can be relieved relatively using magnetic treatment technology of water as research results have conveyed valuable impacts of electromagnetic and magnetic field treatments in numerous agricultural circumstances.
In Egypt, the available studies and application of magnetic treatment technology in agriculture is very limited. Therefore, this research was conducted to investigate the influence of magnetic field treatment using drip irrigation system with different irrigation distances on the quality of saline groundwater for irrigation and in turn impacts of magnetized groundwater on irrigated sandy soils properties and cultivated crop production under arid conditions. Two field experiments were carried out at different desert regions of Egypt (Wadi El Natrun Depression and Sinai Peninsula) to study impacts of magnetic field treatment on different groundwater quality parameters and then to study impacts of using magnetized groundwater produced for irrigation on crop yield (peach in Wadi Al Natrun and maize Sinai Peninsula) and changes in irrigated sandy soil properties under desert conditions.
First field experiment was conducted on peach trees at a private farm of Egypt Renaissance Farm in Wadi Al Natrun district, Behera Governorate, Egypt, during the agricultural season 2016. Second field experiment was conducted on maize crop at the experimental facilities of the Agricultural Research Center, Sinai Regional center for Horticultural crops in Sinai Governorate, Egypt, during the agricultural season 2017. The experimental sandy soil field for both experiments was drip irrigated from magnetized and unmagnetized well waters which were slightly different in their salinities. The magnetic field treatment was applied using AQUA-PHYD treatment device provided by OAKWOODE company with a capacity range of 0.75 T (Tesla) during Wadi El Natrun experiment for peach irrigation and 1 T (Tesla) during Sinai experiment for maize irrigation.
Both experiments were carried out using randomized complete block design consisted of 24 plots with three replicates. The experimental design included two factors, the first was type of irrigation water including (magnetized and unmagnetized) and the second factor was involved drip irrigation distances i.e., 200, 400- and 600-meters distance from the magnetic device in Wadi El Natrun experiment and irrigation distances i.e., 100, 200- and 300-meters distance from the magnetic device in Sinai Peninsula experiment.
Results of this research are concluded under these main headings:
1-Impacts of magnetic field treatment on groundwater quality for irrigation.
No significant changes in water quality indices between magnetized water and unmagnetized were observed by magnetic field treatment. Irrespective of the ability of magnetic field treatment to slightly change chemical composition and criteria of magnetized water than in unmagnetized groundwater, however, the suitability classes of magnetized water still situated at the same categories of unmagnetized water. However, under the conditions of this study when magnetized water was used in irrigation, soil properties and maize and peach crop production were changed significantly compared to irrigation with unmagnetized water.
Results of this research confirmed that implementation of magnetic treatment technology by a magnetic device optimized magnetized water in its ability to dissolve soil salts and ensures to lessen salts in the root zone by increasing soil moisture and an increase transport of nutritious minerals. In general, magnetic water treatment allows irrigation with magnetized saline water with little detrimental impacts on peach and maize crops compared to irrigation with unmagnetized groundwater.
2- Impacts of magnetic field treatment on water and fertilizer use efficiency.
Water use efficiency (WUE, kg kg-1) and productivity were assessed mainly by moisture content in root zone, discharge emitter (L h-1), clogging emitter %, irrigation system application efficiency, while fertilizer use efficiency was assessed (FUE, kg kg-1) by nitrogen use efficiency NUE (kg kg-1), phosphorus use efficiency PUE (kg kg-1) and potassium use efficiency KUE (kg kg-1). Results of this study showed that when irrigated with magnetized water, soil moisture content in root zone increased significantly from 9.45 for control treatment (irrigated with unmagnetized water) to 12.03 % in the first 200 m irrigation distance from the magnetic field device. Moisture content in root zone increased significantly as the irrigation distances increased from 0 to 200 m distance and decreased significantly as the irrigation distances increased from 200 to 400 m and 600 m distances.
This indicates that the effect of magnetizing irrigation water decreases with increasing the irrigation distance from the magnetic device at the head of the field. The same trend was observed in discharge emitters (L h-1) and water use efficiency. By contrast, clogging emitters % decreased significantly from 12.5 for control treatment to 8.21 % in the first 200 m irrigation distance from the magnetic field device. Also, clogging emitter percentage increased again significantly as the irrigation distances increased above 200 m from the magnetic device at the field head confirming the irrigation distance effect on the magnetized water efficiency.
Irrigation with unmagnetized water induced wetted soil volume of 2575.68 cm3 reflecting low drip irrigation application efficiency of 64.07 %, while wetted soil volume was 2919.24 cm3 reflecting high water application efficiency of 72.62% for irrigation with magnetized water. Soil moisture content, uniformity of water distribution and emitters discharge variations in drip irrigation increased with irrigation by magnetic water compared to unmagnetized water. Therefore, the use of magnetized water for drip irrigation is recommended to achieve higher moisture distribution uniformity and emitters discharge and consequently increase in the crop yields and productivity.
Results of this study showed that irrigation with magnetized water increased significantly nitrogen use efficiency NUE (kg kg-1), phosphorus use efficiency PUE (kg kg-1) and potassium use efficiency KUE (kg kg-1) compared to control treatment (irrigated with unmagnetized water). Fertilizer use efficiency (FUE, kg kg-1) increased significantly as the irrigation distance increased up to 200 m distance afar from the magnetic device and decreased significantly as the irrigation distances increased above 200m from the magnetic device.
3-Impacts of magnetic field treatment on sandy soil properties.
Results indicated the higher efficiency of irrigation with magnetized water in improving soil physical and chemical properties in the soil profile compared to unmagnetized water. Soil moisture distribution area and volume of water, soil field capacity and consequently the available water in the investigated sandy soil irrigated with magnetized water was higher than control. Soil moisture content in root zone decreased insignificantly as the irrigation distances increased from 100 to 200 m and 300 m away from the magnetic field device. This indicates that effect of magnetic treatment on irrigation water decreases as the irrigation distance increases from the magnetic device at the head of the field.
High significant impacts observed of magnetic field treatment on the investigated sandy soil are the removal of excess soluble salts away from the root zone, increasing soil pH values, and the dissolving of soluble cations and anions such as chloride, carbonates, sodium and sulfates. Results showed that irrigation with the magnetically treated water has an effective impact on reducing sodium and chloride in the root zone and lessening levels of main soil soluble cations and anions confirming that the magnetized water increased solubility and leachability of salts from the soil profile. Magnetic field treatment of irrigation water caused leaching salts below root zones, reduced sodium and chloride accumulation, decreased Na/Cl ratio from 1.01 to 0.89 which mitigated the negative impacts on maize plants in the root zone. In addition, a significant decrease in soil salinity in terms of electrical conductivity (EC) and sodium adsorption ratio (SAR) in soils irrigated with magnetically treated saline water was observed.
4-Impacts of irrigation with magnetized water on crop yield.
As water and fertilizer use efficiency is based on the amount of fertilizer and water units required to produce a unit of crop yield, thus, the efficiency of water productivity and N use efficiency for maize increased from 1.02 for water use efficiency and 1.66 for nitrogen use efficiency before magnetic treatment to 1.97 and 4.46 Kg Kg-1, respectively. The efficiency of water productivity and NPK use efficiency for peach increased from 5.82 and 8.24 before magnetic treatment to 6.88 and 10.13 Kg Kg-1, respectively. Results stated that irrigation with magnetized water improved soil physical and chemical properties and consequently increases water availability and fertilizer uptake and enhances maize and peach growth and productivity compared to irrigation with unmagnetized water.
Conclusion and future studies
Based on the experiments conducted in this study and on the results obtained herein, it could be concluded that:
1- No significant changes in properties of magnetized groundwater from unmagnetized water was observed by magnetic field treatment, nevertheless water use efficiency and productivity, NPK fertilizers use efficiency and peach and maize crop production were increased significantly when irrigated with magnetized water.
2- Results of this study indicated that there were no significant changes in water suitability criteria for irrigation of magnetized water from unmagnetized was observed by magnetic field treatment. However, irrigation with magnetized water increased significantly water and fertilizer use efficiency and productivity and consequently increased peach and maize crop yield over irrigation with unmagnetized water.
3- Impact of magnetized irrigation water decreases with increasing the irrigation distance from the magnetic device at the head of the field.
4- Magnetic field treatment of irrigation saline water permits irrigation without any harmful impacts on field crops.