**2.6 Selection of soil preparation site**

*Irrigation - Water Productivity and Operation, Sustainability and Climate Change*

absence of good drains [40].

ing the following:

2.Distillation

4.Ion exchangers

3.Electrical switchboard

materials are used for the treatment of salinity.

1.Chemical deposition using CaO lime

5.Membranes or so-called reverse osmosis

6.Evaporation and condensation by the rays of the sun

It is noted that these washing needs calculated in the example are very high and may not be followed, especially because of the lack of irrigation water or the

**2.5 Magnetic water to overcome saltwater and make it suitable for agriculture**

Many countries in the world, including the Arab countries, suffer from the loss of water of the river. Therefore, desalinated saltwater is available from seawater and groundwater. In fact, there are several techniques to desalinate salty water, includ-

There is an excellent way to decompose using magnetic separation. This efficiently removes up to 99% and more. This is because of the salinity of the water (the presence of positive ions and other negative ions), but these ions do not attract toward the magnet, so scientists thought of the physical center attracted by the negative ions and positive ions and attracted them to the center of magnets and this is called Feret Fe3O4, which is thrown in the saline water to be reanalyzed and attracted to the negative and positive ions by the magnetic field, which penetrates water for purifying it. Electrical dialysis has been commercially known since the 1960s, 10 years before reverse osmosis. The cost is effective for desalination of saline water wells and makes the decision for attention in this regard. The electrolysis technique is based on the following general principles. The electrolysis unit consists of several hundred pairs of cells connected to each other by electrodes called a compound of membranes. Feeding water flows simultaneously through passages through the cells to provide the flow of

desalinated water as the concentrated water passes through the compound.

Based on the design of the system, it is possible to add chemicals in the compound to reduce the voltage and prevent the formation of crusts. Feed water must be treated from the outset to prevent substances that sweat membranes or block narrow channels in cells from entering the membrane compound. Feed water is rotated through the compound with a low-pressure pump to overcome water resistance as it passes through narrow passages. A rectifier is often installed to convert the oscillating current into a direct current supplied to the electrodes from outside

Therefore, the tolerance of the plant for salinity is calculated on the basis of the ECe score, where a 25% reduction in yield occurs in case of potatoes at ECe = 3.8. Thus, the washing requirements of potato = 1 × (100/3.8) = 26% more than the amount of water assessed for each irrigation as washing needs to wash the accumulated salts in the area of spreading the roots and away from them. Commercial sulfuric acid is injected with irrigation water at a rate of 2 l per feddan per week for a month. This removes the salts from the roots and removes them on the surface of the soil, thus improving the growth of the plants. Some natural compounds and raw

**64**

Land processing and settlement are important factors in irrigated agriculture, especially when using seawater in irrigation. As is known in irrigated agriculture, salts tend to accumulate and redistribute in the soil sector, where salinity occurs in the field. For example, high areas are increasingly accumulating salt. Therefore, the land should be divided into pieces that may be different in size, but attention should be paid to settling the soil surface in one piece.

Many soil species have been successfully used in clay land to sand dunes and it is important that the soil is good for natural drainage. It is therefore necessary to plow the soil to a depth of 1 m to improve drainage especially in heavy land. When sandy soil is compressed under the surface layer, it must be prepared in terms of deep plowing, surface tillage, settlement, agriculture, and irrigation.

Although many halophytes bear high ground water, interest in drainage is an important factor in resisting salinization. In the case of heavy land, shallow banks must be made in the form of a letter V, at a depth of half a meter, and in dimensions of 10–20 m, to be drained into deep drains and can be drained through water pumps back into the sea.

The surface of the desert sea has a shallow reservoir of groundwater saline that extends to several kilometers of sea level. However, irrigation by seawater will cause damage to any groundwater reservoir. Therefore, hydrological studies should be carried out for the aquifers of the area to be used for irrigation by seawater (depth quality—quantity). The hydrophysical characteristics of the soil must be studied. If the site is located next to a mountain range parallel to the coast as in the case of the Red Sea, the fresh water that collects under the mountain valley or on the sandy shoreline must be maintained.

One of the most important restrictions on the use of seawater to produce halophytes is how to manage water. It is necessary to prevent the accumulation of salts in the rhizosphere. This is a condition other than freshwater irrigation where irrigation is based on the level of soil moisture. In traditional irrigation conditions, irrigation occurs when the soil moisture is reduced to 50%. However, in the case of seawater irrigation and the lack of ground moisture to 50%, the salinity level in the root zone is twice the salinity level of seawater, which has a severe effect on the plant. For most halophytes, it was found that the moisture deficiency should not exceed 25% to reduce the chance of increasing salt concentration between the irrigation in the soil sector. It is also necessary to add washing needs about 25% or more in each rye to wash the salts and expel them below the root area.

Short irrigation and high-salt washing are therefore key to achieving success and achieving high yields of halophytes using seawater. For example, in the case of sand dunes or sandy beaches, irrigation should be carried out regularly on a daily basis during the summer season, while in sandy soil, which can't retain enough water, irrigation can be done every day and every 10 days in the winter season.
