Calculating Tomato Irrigation Needs for 1 Acre in Arid Climate

Determining exact water requirements for an acre of tomatoes in a low-rainfall area depends on several site-specific factors. Without them, any estimate would be a guess.

Essential Data Needed

To calculate precise irrigation volume, provide:

1. Crop water requirement for your tomato variety (peak daily ETc in mm or inches).
2. Local reference evapotranspiration (ETo) rate for the growing season.
3. Soil type and infiltration rate (sandy, loam, clay) to determine application depth and frequency.

Why These Matter

• Tomatoes need 400–800 mm (16–32 inches) per season depending on climate.
• Sandy soils require frequent, light irrigation; clay soils need less frequent, deeper watering.
• Drip irrigation efficiency (85–95%) vs. sprinkler (70–80%) drastically changes volume.

Once you have these numbers, a simple formula applies:
Volume (liters) = Area (m²) × Crop Water Need (mm) ÷ Irrigation Efficiency

For a rough starting point: 1 acre ≈ 4,047 m². At 6 mm/day peak ETc with drip (90% efficiency), that's ~27,000 liters/day. But get local data for accuracy.