Reducing the salinity effect on vegetables

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what is the salinity of soil?.

salinity effect on tomato

Soil salinization is a significant problem in the world's dry and semi-arid areas. Soil salinity is a buildup of dissolved salts in the root zone at a concentration high enough to obstruct the plant's optimum growth and render the soil strip an unsuitable habitat. The roots grew bigger and bigger. Sodium, calcium, magnesium, chloride, and sulfate are the most common soluble salts, with potassium, bicarbonate, nitrate, and boron appearing in smaller amounts.

Effect of water balance on soil salinity:

The water balance in the area influences salt buildup in the soil and is influenced by climatic, topographic, and human activities.

The water balance is the balance between inputs (precipitation) and outputs (evaporation). When the water balance favors sedimentation in wet places, evaporation is favored in dry parts, and evaporation energy may range from 1000 to more than 2000 mm per year.

Plants' responses to salinity:


Two processes, namely the rise in osmotic pressure and the cumulative effect of harmful ions, are known to have a deleterious influence on plants and soil.

First, there's the tremendous osmotic pressure.

When the amount of salt in the soil increases, the osmotic pressure in the area where the roots spread increases. In order for the plant to resist these unsuitable conditions in the soil solution, the plant cells raise the internal osmotic pressure of the cytoplasm. This causes the plant to lose the vital energy needed for development and growth, resulting in weakness and lack of productivity.

The following equation may be used to determine the osmotic pressure of the earth's solution:

(Electrical conductivity in mol/cm x 0.36 = osmotic pressure (atmosphere).

Second, harmful ions have a cumulative impact.

When there is a high concentration of salts in the soil solution, their action enhances the absorption rate of harmful ions such as chlorine, boron, and sodium via the roots.

The high concentration of these elements in the plant's leaves makes eating and absorbing other nutrients difficult.
Furthermore, raising its concentration is enough to produce ionic toxicity in plants. For example, the impact of boron on plants is regarded as a qualitative effect since it influences the development of many plants when its concentration in the ground solution surpasses one part per million, and increasing the concentration of the element sodium causes plant harm.

As we can see, the salinity of irrigation water has an impact on soil fertility and plant productivity:

Depending on the type of soil, the salinity of irrigation water influences soil fertility by accumulating dissolved salts on the soil surface and in the root zone.

The use of salty water for irrigation, particularly in muddy regions, damages
the soil structure, which makes it less porous and ventilated.

It is well known that salty water high in cations, particularly sodium Na+, transforms soil clay into an unstable sodic clay that disintegrates fast and disperses when exposed to rain.

Because agricultural crops vary in their sensitivity to the salts present in irrigation water, the salinity of irrigation water impacts plant production.
Plants with salinity symptoms

There are several signs of salt on plants, which are comparable to the symptoms of drought caused by a lack of irrigation and are outlined below:

1- The leaves seem to be dark green or blue in hue.

2- The burning of the leaf margins, followed by the drying of the leaves
3- miniature plants

For physiological reasons unique to plants, different vegetable plants have various levels of salt tolerance.

The table below shows vegetables' tolerance to EC soil and water and the magnitude of yield reduction at various salt levels.
Treatment of soil salinity

One of the most challenging procedures is the treatment of salinity.


As a result, effort must be made to regulate and cohabit with salts in the soil so that they do not exceed allowed limits via the integration of agricultural activities such as plowing, fertilization, irrigation, drainage, and salinity treatment by following the steps below:

1- Soil amendment using agricultural gypsum.

2- The amount of gypsum supplied is determined by the soil analysis.

3-Agricultural gypsum is supplied yearly at a rate of 0.5 -1 tons per feddan (4200m) if the salinity rate in the ground is less than 4 mm. If the salinity is moderate (4-8 mm), the quantity of agricultural gypsum used per feddan should be raised to 2-4 tons. If the study shows that the soil is saline with a high percentage of 8-12 mm, the number of people who live there will
increase.

2- The following system must be used in areas where soil samples are not evaluated, the following system shall be followed:

A- Use two plows to plow the ground.

B—Soil cleaning is done weekly using immersion or spray irrigation at 100 cubic meters per feddan. It is preferable to monitor the salinity of the soil after each irrigation to determine the effect of washing on salinity and whether the washing process continues.

C - Adding 20 cubic meters of compost per acre (not rubbish) + 200 kg of superphosphate - this is for vegetable cultivation - as for the cultivation of trees, 5 cubic meters of mangrove + 50 kg of superphosphate are added on the planting line only and stirred to a depth of 60 cm and a width of 80 cm. It is recommended that organic fertilizer be sterilized by solar sterilization or composted organic fertilizer be utilized. 

The organic fertilizer is decomposed in one area, well-irrigated until saturation, and covered with plastic for two to three irrigations.

d- A final cleaning is conducted.

3- Fertilizer rates are added with the installation of the necessary cleaning demands with a proper drainage system. The cleaning needs of plants, which are added with irrigation water, are determined using the following equation:

The washing requirements = the degree of salinity of the irrigation water (in millimoles) x (100/ the degree of tolerance of the plant to salinity in a million)

The value of the plant's degree of tolerance to salinity with malolose is obtained from specific tables showing the percentage of crop loss at each degree of EC.

Example: It is essential to estimate the washing needs of pepper plants watered with water with an electrical conductivity degree of 1 mmose/cm at 25 °C, noting that the EC at which no crop decline occurs is 1.5 mmose.

Solution: Pepper cleaning requires = 1 × (100/1.5) = 67 percent

That is, to avoid any shortage in the pepper crop that is irrigated with water with a degree of salinity of 1 mmole/cm, it is taken into account to increase the amount of water needed for each irrigation by 67 percent, as washing needs to wash the accumulated salts in the area of ​​​​the spread of the roots and drain them away from them.

It is emphasized that these calculated cleaning needs in the example are very high and may not be possible to follow, mainly due to a lack of irrigation water, sufficient drainage, or a combination of the two.

 Therefore, the degree of tolerance of the plant to salinity with maltose is estimated based on the degree of EC at which a decline in yield occurs. The capacity of pepper at a degree of EC = 3.3 is 30 percent.

Therefore, the washing needs of pepper = 1 x (100/3.3) = 30 %

4—Commercial sulfuric acid is injected with irrigation water at a rate of 2 liters per feddan every week for a month, as this leads to the ejection of salts from around the roots and their removal from the surface of the soil, which improves plant growth.

5- Use of various chemical substances for salinity therapy.