What is a water budget in irrigation planning?

• A. A budget for purchasing irrigation equipment.
• B. A plan balancing water supply and plant demand to determine irrigation frequency and volume, ensuring sustainable use.
• C. A schedule for rainfall events.
• D. A method to calculate fertilizer needs.

Answer: (B)

Understanding water budgets in irrigation planning means looking at how much water is available to the crop and how much water the crop is expected to use, then planning irrigation accordingly. It combines inputs like rainfall and stored soil moisture with outputs like evapotranspiration and drainage to determine how often to water and how much to apply, aiming for sustainable use by meeting plant needs without overwatering, leaching, or wasting water. This is why the description focusing on balancing water supply and plant demand to set irrigation frequency and volume is the best fit. It isn’t about purchasing equipment, scheduling rainfall events alone, or calculating fertilizer needs.