Question

Water requirement of a crop includes

• A. Evaporation only
• B. Evapotranspiration only
• C. Evapotranspiration and losses such as deep percolation
• D. Evapotranspiration, deep percolation, leaching requirement and pre-sowing irrigation

Hint:

Total Water Requirement $WR = ET + \text{Percolation} + \text{Leaching} + \text{Special needs (puddling, pre-sowing)}$.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Total crop water requirement (WR) is the total quantity of water required by a crop from land preparation to harvest.
Key Formula or Approach:
\[ \text{WR} = \text{ET} + \text{Application \& Conveyance Losses (Percolation)} + \text{Leaching Requirement (LR)} + \text{Special Needs (Pre-sowing, Puddling)} \]

Step 2: Detailed Explanation:
Crop water requirement accounts for all essential water needs:
1. Consumptive needs: Evapotranspiration (ET).
2. Inevitably lost water: Unavoidable deep percolation and application losses.
3. Salinity management: Leaching requirement to maintain root zone root salinity balance.
4. Special cultural operations: Pre-sowing irrigation, nursery raising, puddling, and land preparation.

Step 3: Final Answer:
Thus, crop water requirement includes Evapotranspiration, deep percolation, leaching requirement and pre-sowing irrigation, matching option (D).