Question

9) Describe each of the four causes of salinization

Answer 1

Salinization is the increase salt concentration in the soil to an extent which is toxic for the plants .Salt in the soil decreases osmotic potential of the soil so that plants cannot absorb water from the soil. When the soil is salty, the soil has greater concentration of solute than the roots,so plants cannot get water from it .According to osmosis water moves from the area with the lower concentration of the dissolved solute to the higher concentration of the same. We all know that excess salt can be toxic for the plants but main problem is the inability to absorb water from the soil.

Causes of salinization-

1. Natural causes- Mostly saline soils are developed due to natural geological, pedological and hydrological processes.Climatic factors and poor water management can also increase salinization. In arid and semi arid areas. Evaporation of water from the soil also increases salt content. Another reason is tides in the sea and main cause is the entry of saline water in the river.Cyclic salts are sea salt carried to the land by wind and deposited by the rainfall and mainly these are sodium chloride.

2. Athropogenically induced salinity- Other than the natural processes man also increases salt content in the soil which is know as secondary reason of salinization. Improper irrigation is the main cause. poor quality of water is use for irrigation and in the end salt builds up in the soil which increases the salinity. Anthropogenic salinization occurs in arid and semi arid areas due to waterlogging brought about by improper irrigation. Human activities can also cause salinization.

A. Deforestation- It is the major cause of salinization and alkalinization of soils that result in the migration of salt in upper and lower layers of soil. It also decreases the average rainfall and increases the average temprature.Top soil rapidly decreases in the absence of natural green soil. Erosion occurs because there are no trees which act as a buffer between rain and soil and soil erosion leads to the accumulation of soil in the river . All these factors leads to flooding and increase salinity of soil.

B. Accumulation air- borne and water- borne salt in soil- Chemical emission from the various industries can increase the salt content in the upper layer of soil. Waste water with the excess salt content from the municipalities and sludge can contaminate the soil so causes salinization.

C. Contamination with chemicals- It often occurs in green houses.

D. Overgrazzing- It occurs in arid and semi arid areas where the natural soil is poor so cannot satisfy the hunger of animals .It somtimes leads to the desertification also.

So these are the main four causes of salinization.