Question

The ratio of crop yield to the amount of water depleted by the crop during ET is called as

• A. crop water use efficiency
• B. field water use efficiency
• C. water application efficiency
• D. water storage efficiency

Hint:

- Crop Water Use Efficiency = Yield ET (directly used water).
- Field Water Use Efficiency = Yield Total Water Applied (includes system losses).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Water Use Efficiency (WUE) is a metric used to evaluate how effectively a crop converts available water into harvestable yield.
It is classified into crop water use efficiency and field water use efficiency based on how the water input is measured.
Key Formula or Approach:
The formulas for these efficiencies are:
- Crop Water Use Efficiency (CWUE):
\[ \text{CWUE} = \frac{Y}{ET} \] where \( Y \) is the crop yield and \( ET \) is the amount of water lost through evapotranspiration (depleted by the crop).
- Field Water Use Efficiency (FWUE):
\[ \text{FWUE} = \frac{Y}{WR} \] where \( WR \) is the total water requirement, which includes ET, deep percolation, runoff, and water used for land preparation.

Step 2: Detailed Explanation:
The question defines the ratio of crop yield to the volume of water lost or depleted via evapotranspiration (ET).
Since this ratio accounts specifically for water used directly by the crop (transpiration) and evaporated from the surrounding soil (evaporation), it represents the Crop Water Use Efficiency (CWUE).
Field water use efficiency is a broader measure that includes all water applied to the field, making it lower than crop water use efficiency due to conveyance and application losses.

Step 3: Final Answer:
The ratio of crop yield to the water depleted during ET is called crop water use efficiency.