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Irrigation Water Calculator

Calculate how much water your crop needs for irrigation. Enter crop type, field area, and soil type to get daily water requirement, pump hours, and monthly water volume.

Crop
Daily water requirement8 mm/day
1 mm (low)15 mm (high)
Field Area
#
Irrigation Method
Pump discharge rate
water needed per day
Daily water requirement (gross)
Daily pump run time
Weekly water requirement
Monthly water requirement
Net water requirement
Depth applied per irrigation
Frequently Asked Questions
How is irrigation water requirement calculated?

Water requirement = Crop evapotranspiration (ET) in mm/day × Field area in m². Convert mm to litres: 1 mm of water per 1 m² = 1 litre. Account for irrigation efficiency to get gross water requirement.

What is irrigation efficiency?

Irrigation efficiency is the percentage of water pumped that reaches the crop root zone. Flood irrigation: 50-70%. Sprinkler: 75-85%. Drip: 85-95%. Higher efficiency means less water pumped for the same crop need.

What is evapotranspiration (ET)?

Evapotranspiration is the total water lost from soil evaporation and plant transpiration per day, measured in mm. Reference ET (ETo) depends on temperature, humidity, and wind. Crop ET = ETo × crop coefficient (Kc).

How many hours should I run my irrigation pump?

Pump hours = Gross water requirement / Pump discharge rate. For 2 acres of sugarcane needing 10,000 litres/day with a 5,000 litre/hour pump: 2 hours/day. Run in early morning to reduce evaporation losses.

What is drip irrigation and when should I use it?

Drip irrigation delivers water directly to the root zone through emitters on pipes. Best for orchards, vegetables, and water-scarce regions. Saves 30-50% water vs flood irrigation. Higher installation cost but lower operating cost.

How do I calculate the number of drip emitters needed?

Number of emitters = Field area × plant density. Each emitter typically covers 1-4 m² depending on crop spacing. Flow rate per emitter (2-4 L/hour) determines the total pump capacity needed for simultaneous operation.

What is sprinkler irrigation?

Sprinkler irrigation uses pressurised pipes and nozzles to spray water over crops like rainfall. Suitable for field crops, vegetables, and orchards. Provides 80% efficiency vs 65% for flood. Requires electricity or diesel for pressurisation.