The process that uses reclamation of saline soil, in which agricultural land is flooded with water to a depth of about 20-30 cm, is known as:
- Asub-surface drainage
- BleachingCorrect
- Csurface drainage
- Dwashing
Solution
Concept
In leaching, saline land is flooded with 20-30 cm of water. The salts dissolve and move down below the root zone, and drains remove them.
Step-by-step solution
1. Saline soil has too much soluble salt in the root zone. 2. To remove the salt, the land is divided into small plots with bunds and flooded with about 20-30 cm of water. 3. The water dissolves the salts and carries them down by percolation. Sub-surface drains then remove them. 4. This method is called leaching. Answer is (B).
Explanation
Leaching means flooding the saline land with about 20-30 cm of water so the salts dissolve and go down below the root zone. It is repeated until the salt level becomes low. Good drainage is needed with it.
Why the other options are wrong
A: Sub-surface drainage only lowers the water table and removes drain water. It does not mean flooding the land. C: Surface drainage removes extra surface water from the field. D: Washing removes the salt crust from the surface with water flowing over the land, not by deep flooding and percolation.
Shortcut
Flooding + percolation of salts downward = leaching.
Common mistake
Choosing 'washing' because water is used. Washing is only surface removal of salts.
Correct answer: B) leaching