Soil Pollution

Soil Pollution

• Soil pollution is defined as the contamination of soil causing adverse effects on living organisms in it.

 

1. Causes of Soil Pollution

1. Soil erosion : Soil erosion can be defined as the movement of topsoil from one place to another. Soil erosion is a natural process due to wind, flood and due to human activities like - construction, overgrazing, farming and deforestation.

2. Industrial wastes : Various pollutants exists in environment from industrial wastes. Discharge from chemical industries, fertilizer company, pharmaceutical companies are highly polluting.

3. Urban wastes : Because of modem life style and eating habits the urban wastes are becoming very dangerous to the human beings. Urban wastes include both domestic and commercial wastes. Plastic is used in almost all packed foods, which is a non-degradable material and harmful to the society in long run.

4. Agricultural practice : Use of strong fertilizer, pesticides and inorganic chemicals for increasing yields causes soil pollution. Their effects can be seen even after the crop.

5. Biological agents : Human and animal excreta wastes enter the soil pores and decompose pathogenic bacteria present in those wastes spread infection.

 

2. Effects of Soil Pollution

1. Toxic compounds affects plant growth and human life also.

2. Water logging and salinity makes soil infertile.

3. Hazardous chemicals enter into food chain from soil disturbing the biochemical process.

4. Nervous disorders, gastrointestinal disorder, joint pain, respiratory problems are the effects seen on human beings.

 

3. Control Measures for Preventing Soil Pollution

1. Soil erosion must be prevented or controlled by proper tree plantation.

2. All the wastes from industry, domestic, must be dumped with proper treatment.

3. Use of synthetic fertilizers must be avoided instead natural fertilizers must be preferred

4. Educate people regarding consequences of soil pollution and to prevent soil pollution.

5. Strict enforcement of environment protection law’.

6. Toxic and non-degradable materials must be totally banned.

7. Recycling and reuse of industrial and domestic wastes can minimize soil pollution considerably.

 

4. Impacts of Modern Agriculture

a.  Fertilizers

1. Micronutrient imbalance

• The fertilizer contents are nitrogen, phosphorous and potassium, which are macronutrients. The excess use of fertilizer causes imbalance of micronutrients, which affects the productivity of soil.

2. Blue baby syndrome (Nitrate pollution)

• Nitrate is highly soluble, they leach deep into the soil and can elevate concentrations in groundwater. This results in unacceptable quality for drinking water and may cause serious health problem called Blue Baby Syndrome which leads even to death.

3. Eutrophication

• Phosphorous does not leach but more tightly bound to soil particles. Large amount of phosphorous used in fertilizers carried with soils by runoff water and reaches water bodies causing excessive growth of aquatic plants. This process is called Eutrophication.

• If this process continues, lakes and reserviors becomes choked with algal species. These algae have offensive oders and can kill fish.

• The life of algal species are less they die quickly and pollute the water, which affect the aquatic life.

b. Pesticides

• Pesticides are used to improve the crop yield. Pesticides kill the pets.

First Generation Pesticides

Examples : Sulpher, arsenic, lead and mercury.

Second Generation Pesticides

Example : Dichlorodiphenyl Trichloromethane (DDT).

• Pesticides protect crop from losses due to pests. Pesticides kill not only the pest of concern but also a wide range of other organisms including beneficial insects. They produce number of side effects.

1. Death of non-target organisms

• Pesticides kill several non-target species which are useful to us.

2. Producing new pests (Superpests)

• Some species survice even after applying pesticides. These species generate highly resistant generation which are immune to pesticides and are called superpests.

3. Bio-magnification

• Most pesticides are note bio-degradable and keep on concentrating in food chain. This process is called bio-magnification. Pesticides in bio-magnified form is harmful to human beings.

4. Risk of cancer

• Pesticides may cause cancer as it directly acts as carcinogens and indirectly suppresses immune system.

5. Contamination of ground water

• New pesticides are soluble in water. The surface runoff carries pesticides into streams, lakes and reserviors causing unacceptable level of nutrients and organic compounds (dissolved chemicals). This results in contamination of groundwater supplies.

c. Waterlogging and its Effects

• Waterlogging is the land where water stays for most of the period.

• Waterlogging occurs where clay soil is present excessively. During waterlogging the soil gets filled with water and soil-air gets depleted. Therefore, roots of plants don't get adequate air for respiration. The soil strength decreases and crop-yield falls.

• The soil is then no longer suitable for cultivation.

Causes of waterlogging

1. When soils are over irrigated.

2. Heavy rain.

3. Inadequate drain of water.

Remedy

• Following remedy is suggested to avoid waterlogging.

1. Avoid excessive irrigation.

2. Provide adequate drainage.

3. Bio-drainage trees to avoid waterlogging e.g. Eucalyptus.

Salinity

• The unabsorbed water undergo evaporation leaving behind thin layer of dissolved salts on the top soil. The process of accumulating salts on soil is called salinity.

• The saline soils are characterized by deposition of soluble salts such as sodium chloride, calcium chloride, magnesium chloride, sodium sulphate, sodium bicarbonates and sodium carbonates.

Effects of salinity

1. Because of salinity the soil becomes alkaline and crop yield decreases severely.

2. Salinization of land leads to stunt growth.

3. The land becomes impotent and no crop can be cultivated.

Remedy for salinity

1. The salt layer can be removed by flushing more fresh water.

2. Switch to salt tolerant crops like cotton, suger beet etc.

3. Recharge soil with fertile ones.

4. Providing underground drainage system.

Review Questions

1. What are the impacts of modern agriculture ?

2. Write the impact as of modern agriculture.