1. What is Irrigation Requirement?

The irrigation requirement (IN) is the amount of water needed to supplement natural precipitation to meet crop water demands. It's calculated as the difference between 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 water lost through evapotranspiration and subtracts the water gained from effective precipitation.

3. Importance of Irrigation Calculation

Details: Accurate irrigation requirement 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 in millimeters. Both values must be positive numbers. The result shows the net irrigation requirement.

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 total water loss from the crop system.

Q2: What counts as effective precipitation?
A: Effective precipitation is the portion of total rainfall that is available to plants, excluding runoff and deep percolation.

Q3: How often should irrigation requirements be calculated?
A: For precise irrigation scheduling, calculations should be done daily or weekly based on current weather conditions.

Q4: Are there limitations to this simple equation?
A: Yes, more advanced models consider soil water holding capacity, crop growth stage, and irrigation efficiency.

Q5: How does this relate to irrigation scheduling?
A: The calculated IN helps determine when and how much to irrigate, but must be adjusted for irrigation system efficiency.