Irrigation Calculator
Net Irrigation Needed
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Gross Water
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Gallons per Week
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Flow Rate
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Planning Crop Irrigation
Irrigation = crop demand minus rainfall. One acre-inch = 27,154 gallons. Efficiency accounts for losses.
Typical needs: corn 1.0-1.5 in/week peak, soybeans 1.5-2.0, vegetables 1.0-2.0.
Efficiency by system: drip 85-95%, center pivot 75-90%, sprinkler 65-80%, flood 40-65%.
Frequently Asked Questions
Water for an acre of corn?
Peak growth: 1.5 in/week = about 40,731 gallons/acre/week. Seasonal total: 18-24 inches.
Most efficient system?
Drip at 85-95%. Delivers water directly to roots. Center pivots 75-90%.
When to irrigate?
Use soil moisture sensors, ET data, or visual plant stress. Many use ET scheduling from weather stations.
What is an acre-inch?
Volume to cover one acre one inch deep: 27,154 gallons or 3,630 cubic feet.