If sewage is applied continuously on a piece of land, pores or voids of soil are filled up or clogged. Free circulation of air is thereby prevented and anaerobic conditions develop. At this stage, the land is unable to take any further sewage load. Organic matter decomposes and foul smelling gases are produced. The phenomena of soil are known as sewage sickness of land.

Preventive measures:

In order to prevent sewage sickness of land, the following preventive measures may be adopted

• Alternative arrangement: There should be ample provision of extra land so that land with sewage sickness can be given the desired rest. Alternatively, sewage should be disposed of by some other method when sewage farms are taking rest.

• Depth of sewage: If sewage is applied in excess, the chances of sewage sickness are increased. The land is unable to receive the excess sewage in a satisfactory way and it ultimately clogs up. Depth of sewage on land should be carefully decided by keeping in view the climatic conditions, drainage facilities, nature of crops and characteristics of soil.

• Drainage of soil: Subsoil drain pipes should be laid in sufficient number to collect the percolated effluent

• Intermittent application: Sewage should be applied on land at intervals. The period between successive applications depends on general working of sewage farm and the permeability of soil. Depending on the nature of the soil, this period between successive applications varies from few hours to few weeks.

• Pre-treatment of sewage: sewage should be given some pre-treatment before it is applied on land.

• Rotation of crops: It is desirable to grow different types of crops on a piece of land instead of one single crop. Rotation of crops minimizes the chances of sewage sickness.

• Treatment to land: The land affected by sewage sickness should be properly treated before it is put up in use again. Clogged surfaces should be broken by suitable equipment.