Correct Answer - Option 3 : Sewage sickness
Explanation:
Sewage sickness:
- When sewage is applied continuously on a piece of land, the soil pores or voids may get filled up and clogged with sewage matter retained in them. This phenomenon of soil getting clogged is known as sewage sickness of the land.
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Free circulation of air will be prevented, and the anaerobic condition will develop within the pores.
- The anaerobic condition would stop the aerobic processes and release foul gases like hydrogen sulphides, carbon dioxide, and methane.
Preventive Measures
The following preventive measures may be adopted to avoid sewage sickness:
(i) Sewage should be given primary treatment.
(ii) The soil chosen for effluent irrigation/sewage farming should be sandy or loamy.
(iii) A proper under drainage system (open jointed drains) should be designed.
(iv) Land should be given rest for some time and plowed thoroughly
(v) Rotation of crops to be followed.
(vi) Shallow depths of water should be applied.
