Soil is the layer of organic and inorganic material that forms the top surface of earth’s crust. The organic material is derived from decayed remains of plants and animals. The inorganic material is made up of rock fragments.

Soil pollution is the introduction of contaminants or substances which result in a change of soil quality. Soil pollutants adversely affect the physical, chemical and biological properties of soil and reduce its productivity.

Causes/Sources of soil pollution:

·          Excessive use of pesticides, fertilizers increases toxicity of soil.

·          Discharge and dumping of industrial effluents on land.

·          Accumulation of solid waste i.e. garbage and refuse etc and radioactive substances from nuclear plants.

·          Soil erosion causes loss of top layer of soil and reduces soils holding capacity and makes it less fertile.

·          Open defecation of animals and human beings.

Control of soil pollution:

Bioremediation: It is a technique for treating polluted soil. It utilizes micro-organisms like yeast, fungi, and bacteria to breakdown or degrade hazardous substances into less toxic or non toxic substances like water or CO₂.

Factors that affect Bioremediation include

·          Temperature favorable for organisms.

·          Availability of nutrients (like N, P, K)

·          Availability of H₂O.

·          Availability of Oxygen

It is a four step process which is as follows.

·          Biostimulation: Stimulation of biological activity in the various soil layers

·          Bioventing: Injection of air in the layers of soil

·          Biosparging: Injection of nutrients in the various layers of soil

·          Bioaugmentation