1. What is Irrigation Water Requirement?

The Irrigation Water Requirement (IN) is the amount of water needed by crops that must be supplied through irrigation. It's calculated as the difference between crop evapotranspiration (ET) and effective precipitation (Pe).

2. How Does the Calculator Work?

The calculator uses the basic irrigation requirement equation:

Where:

• \( IN \) — Irrigation need (mm)
• \( ET \) — Evapotranspiration (mm)
• \( Pe \) — Effective precipitation (mm)

Explanation: The equation accounts for the water lost through evapotranspiration and subtracts the water gained from effective precipitation.

3. Importance of Irrigation Calculation

Details: Accurate irrigation calculation is crucial for efficient water use, preventing over-irrigation (which can lead to waterlogging and nutrient leaching) and under-irrigation (which can stress crops).

4. Using the Calculator

Tips: Enter evapotranspiration and effective precipitation values in millimeters. Both values must be non-negative numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is evapotranspiration (ET)?
A: ET is the sum of water evaporated from the soil and transpired by plants, representing the total water loss from the crop system.

Q2: What constitutes effective precipitation (Pe)?
A: Effective precipitation is the portion of rainfall that is available to crops after accounting for runoff and deep percolation.

Q3: When is irrigation needed?
A: When ET exceeds Pe, creating a water deficit that must be compensated through irrigation.

Q4: Are there limitations to this simple equation?
A: Yes, it doesn't account for soil water holding capacity, irrigation efficiency, or crop growth stages which affect water needs.

Q5: How often should calculations be made?
A: Ideally weekly or more frequently during critical growth stages or extreme weather conditions.