Soil pollution is referred to the degradation of soil fertility by removal of useful components and addition of other harmful substances. Soil pollution can be caused by solid wastes as well as chemicals. Fly ash, which is a grey powdery residue of unburnt material, is produced by most industrial furnaces and thermal power stations. Fly ash is deposited in the soil and causes pollution.

Domestic wastes also add a large amount of solid pollutants to the soil.

The solid wastes that cause soil pollution can be grouped into two broad categories:

(i) Degradable pollutants: These include domestic waste and sewage that can easily be decomposed.

(ii) Non-degradable pollutants: These include those pollutants that cannot be decomposed such as plastics, inorganic metallic compounds, oxides, pesticides (DDT) and radioactive substances.

Following are the harmful effects of soil pollution:

(i) It makes the soil infertile.

(ii) It kills the microorganisms living in the soil.

(iii) It affects the crop production.