Question:
Most hazardous element in the irrigation water in relation to crop growth and production is
Most hazardous element in the irrigation water in relation to crop growth and production is
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Sodium hazard is assessed using the Sodium Adsorption Ratio (SAR):
\( \text{SAR} = \frac{[Na^+]}{\sqrt{\frac{[Ca^{++}] + [Mg^{++}]}{2}}} \).
High SAR water causes soil sodicity and structure collapse.
\( \text{SAR} = \frac{[Na^+]}{\sqrt{\frac{[Ca^{++}] + [Mg^{++}]}{2}}} \).
High SAR water causes soil sodicity and structure collapse.
Updated On: Jul 21, 2026
- Potassium
- Magnesium
- Sodium
- Calcium
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Verified By Collegedunia
The Correct Option is C
Solution and Explanation
Step 1: Understanding the Concept:
Water quality is determined by the presence and concentration of specific dissolved ions.
Some ions can adversely affect soil structure, water infiltration, and plant physiology.
Detailed Explanation:
- Sodium ($Na^+$) is considered the most hazardous element in irrigation water.
- A high concentration of sodium relative to divalent cations (Calcium, $Ca^{++}$, and Magnesium, $Mg^{++}$) is measured by the Sodium Adsorption Ratio (SAR).
- When high-sodium water is applied to soil, sodium ions replace calcium and magnesium on the clay exchange complex.
- This causes clay dispersion, soil swelling, and the collapse of soil aggregates.
- As the soil structure is destroyed, a hard crust forms on the surface, drastically reducing soil permeability, aeration, and water infiltration.
- Additionally, sodium is toxic to many crops, causing leaf burn and necrosis.
- Calcium, Magnesium, and Potassium are essential plant nutrients and do not cause soil dispersion.
Step 2: Final Answer:
The most hazardous element in irrigation water is sodium, corresponding to option (C).
Water quality is determined by the presence and concentration of specific dissolved ions.
Some ions can adversely affect soil structure, water infiltration, and plant physiology.
Detailed Explanation:
- Sodium ($Na^+$) is considered the most hazardous element in irrigation water.
- A high concentration of sodium relative to divalent cations (Calcium, $Ca^{++}$, and Magnesium, $Mg^{++}$) is measured by the Sodium Adsorption Ratio (SAR).
- When high-sodium water is applied to soil, sodium ions replace calcium and magnesium on the clay exchange complex.
- This causes clay dispersion, soil swelling, and the collapse of soil aggregates.
- As the soil structure is destroyed, a hard crust forms on the surface, drastically reducing soil permeability, aeration, and water infiltration.
- Additionally, sodium is toxic to many crops, causing leaf burn and necrosis.
- Calcium, Magnesium, and Potassium are essential plant nutrients and do not cause soil dispersion.
Step 2: Final Answer:
The most hazardous element in irrigation water is sodium, corresponding to option (C).
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