WHAT CAUSES SOIL SALINIZATION AND HOW TO PREVENT AND MANAGE

What causes soil salinization and how to prevent and manage it

 What causes soil salinization and how to prevent and manage it

Soil salinization has a negative effect on plant development and causes soil degradation. Saline soils indicate low agricultural productivity, harming the welfare of farmers and the economic situation of the region.

 Managing soil salinity early helps reverse the process. However, heavy pollution leads to the loss of agricultural lands and deserts due to the negative effects of salinity on soil properties. The United Nations University says that around 5,000 acres are lost every day
worldwide due to salinization since 1990, as of 2014.

What is soil salinization?

Soil salinization is the accumulation of excess water soluble salts.  This is usually NaCl table salt. The list is long and includes various compounds of sodium, potassium, calcium, magnesium, sulfates, chlorides, carbohydrates and bicarbonates. In general, soils affected by salt are classified as saline, sodic, and saline-sodium, depending on their content. 

The main effect of soil salinity on growing is the inhibition of water absorption. Even with adequate soil moisture, plants wilt and die due to lack of water absorption. Globally, according to the 2018 Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) report: 

  • about 190 million acres are completely lost; 
  • 150 million acres damaged;
  • 2.5 billion acres are affected by salinization.


What causes soil salinization?

 Soil salinization occurs when soluble salts are deposited in the soil. This happens either naturally or as a result of inappropriate anthropogenic activities, especially agricultural practices. In addition, some soils are initially saline due to salt dissolution and poor drainage.

 Causes of soil salinization include: 

  • dry weather with little rain when excess salt is not removed from the earth;
  • high rate of evaporation, which adds salt to the soil surface;
  • bad water or water that is flooded when the salt is not cleaned due to the lack of a boat;
  • irrigation with water rich in salt, which increases the salt content of the soil;
  • remove weeds that take root and the high water that will come out of it;
  • leakage from underground storage and entering groundwater;

        sea level rise as salt water seeps into the ground;

  • Wind in coastal areas that blow salt air to neighboring areas;
  • immersion in sea water following the evaporation of salt;
  • Improper application of fertilizers when excessive nitrification increases soil salinization

Soil salinity indicator

Salinization can be estimated by considering soil surface, water infiltration rate and vegetation conditions. As salinization progresses, the signs become worse. For example, a little whiteness on the surface turns into a special salt crystal. Besides the visible change, there is indirect evidence of adding more salt. It is bad water behavior or animal behavior when livestock  refuse to drink water because of its salty taste.
 

Surface Changes Because of Salinization

  • wetlands and wetlands;
  • cleaning the ground at the beginning and crystal salt at the next time;
  • increase in water level in furrows;
  • bare soil (where plants do not grow due to salinization);
  • Damage to roads, buildings, etc. ;

      A white or dark ring around the body of water. 

  Salinization Related Indicator in Vegetation

     wilting of plants;
  • crop loss;
  • the decline of living things;
  • the nature of plants that tolerate salt in the area and their capacity to increase.

 

Measure soil salinity

Besides the observation, there are reliable ways to measure the salinity of the soil, for example to monitor the electric current of the Earth using certain devices. With an increase in the concentration of salt in the solution, its behavior increases. Other types of soil salinity tests provide the percentage of sodium that can be converted or the rate of sodium uptake. 


Bad effects of salinization

The consequences of soil salinization are not positive and cover many aspects of the environment and human life. It affects agricultural production and water supply, increases the risk of flooding and soil erosion and reduces biodiversity. 

Agricultural production

The water saturation of the plant depends on the level of salts in the soil and the plant itself. Osmosis absorbs water and moves it from an area with less salt to an area with more salt. When the concentration of salt is too high, it means that the osmotic power of the soil is bad. Plants suffer from osmotic stress when they cannot absorb water, even when it is in the soil. Basically, this process is similar to drought stress caused by lack of water in the soil. As a result, the grass dies. Salinization also impairs nitrogen availability, slows plant growth and leads to fruit failure.
 
Another effect of soil salinity in agriculture is ionic stress due to harmful ions present in soil salts, for example chloride or sodium. In addition to their toxic effects as such, these positively charged ions prevent the availability of other positively charged ions necessary for plant growth (especially potassium and calcium). . The result is the same as the osmotic pressure due to salinization: the plant dies.

 Control and prevention of soil salinity

The best way to combat soil salinization is to prevent it from happening. If this is the case, it is important to eliminate the problem - the sooner the better, before the consequences are bad. So, soil salinization solutions are related to prevention and control.

How to prevent soil salinization?

 Preventing soil salinization involves avoiding excessive salt application. Although plants need a little salt to grow, their need is small compared to the content of the soil that is affected by salt

. Here are some ways to prevent soil salinization:

  • optimize irrigation (reduce salt water consumption, implement irrigation systems, use distilled water, recycle rainwater, and avoid spraying).
  • Add organic matter and nutrients to retain water and reduce irrigation
  • Avoid tilling the soil or using heavy machinery to avoid transferring salt from the soil to the root zone, which causes salinization.
    Use mulch or mulch to protect the soil surface.

How to reduce soil salinity

There are several ways to combat salinization and improve agricultural productivity:
  • Increase drainage for better washing (to remove salt from the soil). 
  • Plant salt tolerant crops to manage economic risks and ensure soil cover.
  • Use a machine to remove the salt crystals from the surface. • Restore balance through chemical changes (eg gypsum or sulfuric acid).
  • Treat seeds with NaCl to improve seed yield.
  •   Reduce evaporation with mulch or crop residues.
  • Grow plants that can absorb water well to avoid prolonged standing water.
  •   Apply fertilizers sensibly, because excessive use of certain fertilizers promotes salinization.  

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