Question

Soil salinity adversely affects plant growth. Arrange the below statements in correct sequence for occurrence of soil salinity in irrigated fields..
A. When area is irrigated excessively over an extended period of time, the ground water level rises.
B. Salts which were orginally present in the irrigation water are thus concentrated on the land surface.
C. When it reaches a height which is equal to the capillary rise of moisture in the soil, the soil moisture is brought to the surface.
D. Soil moisture evaporates leaving the salts at the surface.
Choose the correct answer from the options given below:

• A. A, D, B, C
• B. A, C, D, B
• C. A, B, C, D
• D. A, D, C, B

Hint:

Remember the chain of events: Excess Irrigation $\rightarrow$ Water Table Rises $\rightarrow$ Capillary Action $\rightarrow$ Evaporation $\rightarrow$ Salt Accumulation. This classic cycle describes how productive agricultural land becomes saline.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Soil salinization is the accumulation of soluble salts in the root zone and on the soil surface.
In irrigated agriculture, this is often driven by a rising water table, which brings dissolved salts upward via capillary action.
Once the water reaches the surface, evaporation leaves these salts behind, gradually concentrating them over time.

Step 2: Detailed Explanation:
Let us trace the physical steps of this process in order:
1. Step 1 (A): Excessive irrigation water applied over an extended period of time deep-percolates past the root zone, raising the local groundwater level.
2. Step 2 (C): As the water table rises, it eventually reaches a depth from which water can easily climb to the surface via capillary action (the capillary fringe).
3. Step 3 (D): Once this capillary water reaches the surface, the sun and wind cause the soil moisture to evaporate into the atmosphere.
4. Step 4 (B): Because only pure water evaporates, the dissolved salts originally present in the groundwater and irrigation water are left behind, accumulating and concentrating on the soil surface.
This logical physical progression follows the sequence: A $\rightarrow$ C $\rightarrow$ D $\rightarrow$ B.

Step 3: Final Answer:
The correct physical sequence for the occurrence of soil salinity in irrigated fields is A, C, D, B.
Hence, the correct option is (B).