Question

Given below are two statements:
Statement- I : Irrigation frequency indicates the number of days between irrigations during periods of without rainfall.
Statement- II : Irrigation frequency depends on the consumptive use rate of a crop and the amount of unavailable moisture in the crop root zone.
In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement I and Statement II are correct
• B. Both Statement I and Statement II are incorrect
• C. Statement I is correct but Statement II is incorrect
• D. Statement I is incorrect but Statement II is correct

Hint:

Remember the soil moisture classifications:
- Available Moisture \(\rightarrow\) Held between Field Capacity and Wilting Point (used to calculate irrigation interval).
- Unavailable Moisture \(\rightarrow\) Held below Wilting Point (cannot be extracted by plants).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Irrigation frequency is the interval (measured in days) between two consecutive irrigation events during periods without rainfall.
It determines the scheduling of irrigation to ensure that crops do not suffer from water stress.

Step 2: Detailed Explanation:
Let us analyze both statements:
- Statement I: By definition, irrigation frequency is the time interval (in days) between successive water applications during dry spells.
It represents how often the crop needs to be irrigated to replenish soil moisture.
Therefore, Statement I is correct.
- Statement II: The mathematical relationship for irrigation frequency (\( IF \)) is given by:
\[ IF = \frac{\text{Readily Available Moisture (RAM)}}{\text{Daily Consumptive Use Rate (CU)}} \]
- Consumptive Use Rate: This is the daily rate at which water is transpired by the crop and evaporated from the soil surface.
- Readily Available Moisture: This is the fraction of available moisture that can be easily extracted by plant roots without causing stress.
- Unavailable Moisture: This is the soil moisture held tightly by soil particles at or below the permanent wilting point, which plants cannot extract.
Since the frequency of irrigation depends on the *available* moisture rather than the *unavailable* moisture, Statement II is incorrect.
Therefore, Statement I is correct, but Statement II is incorrect, making option (C) the correct choice.

Step 3: Final Answer:
Statement I is correct but Statement II is incorrect.