Question

Choose the correct sequence for leaching operation A. Water table rise, over irrigation, accumulation of salts, leaching B. Over irrigation, water table rise, accumulation of salts, leaching C. Leaching, accumulation of salts, water table rise, over irrigation D. Accumulation of salts, leaching, water table rise, over irrigation Choose the correct answer from the options given below:

• A. A Only
• B. B Only
• C. C Only
• D. D Only

Hint:

Salinity development sequence: \[ \boxed{ \text{Over irrigation} \rightarrow \text{Waterlogging} \rightarrow \text{Salt accumulation} \rightarrow \text{Leaching} } \] Leaching removes salts from the root zone by downward movement of water.

Answer 1

The Correct Option is B

Concept: Leaching operation is performed in irrigated agriculture to remove excess soluble salts accumulated in the root zone. The sequence generally occurs as:
• Excess irrigation water is applied
• Water table starts rising
• Salts accumulate in soil due to capillary action and evaporation
• Leaching is carried out to flush salts downward Leaching is therefore considered a reclamation practice after salt accumulation.

Step 1: Understanding over irrigation. Initially farmers apply excessive irrigation water. This condition is called: \[ \boxed{ \text{Over irrigation} } \] Over irrigation may cause:
• Excess percolation
• Rise in groundwater table
• Waterlogging problems

Step 2: Understanding rise in water table. Continuous over irrigation causes: \[ \boxed{ \text{Rise in water table} } \] When groundwater approaches the soil surface:
• Capillary rise becomes significant
• Salts move upward

Step 3: Understanding accumulation of salts. As water evaporates from the soil surface:
• Water disappears
• Dissolved salts remain behind Thus: \[ \boxed{ \text{Accumulation of salts occurs} } \] This causes salinity hazards and affects crop growth.

Step 4: Understanding leaching operation. To remove salts:
• Additional clean water is applied
• Salts are dissolved and moved below root zone This process is called: \[ \boxed{ \text{Leaching} } \]

Step 5: Writing the correct sequence. Hence the correct chronological sequence is: \[ \boxed{ \text{Over irrigation} \rightarrow \text{Water table rise} \rightarrow \text{Accumulation of salts} \rightarrow \text{Leaching} } \]

Step 6: Checking all options carefully. Option (A): Incorrect because over irrigation occurs before water table rise. \[ \boxed{ \text{Option (A) is incorrect} } \] Option (B): Correct sequence. \[ \boxed{ \text{Option (B) is correct} } \] Option (C): Incorrect because leaching occurs at the end. \[ \boxed{ \text{Option (C) is incorrect} } \] Option (D): Incorrect sequence. \[ \boxed{ \text{Option (D) is incorrect} } \] Final Conclusion: The proper sequence for leaching operation is: \[ \boxed{ \text{Over irrigation} \rightarrow \text{Water table rise} \rightarrow \text{Accumulation of salts} \rightarrow \text{Leaching} } \] Hence the correct answer is: \[ \boxed{ (B) } \]