An irrigation schedule calculator determines how often to irrigate and how much water your crops need based on crop type, soil water-holding capacity, and climate. Over-irrigation wastes water and energy; under-irrigation at critical growth stages causes irreversible yield losses. Enter your field details below to get a recommended schedule and total weekly water volume.
Irrigation Schedule Generator
How to Use the Irrigation Schedule Calculator
Effective irrigation scheduling balances crop water demand against soil storage capacity and climate conditions. This irrigation schedule calculator generates recommended intervals and volumes for common field crops by combining crop evapotranspiration rates with soil water-holding capacity data.
Understanding the Inputs
Crop type determines peak water use (evapotranspiration): corn at tasseling uses 0.35 inches/day while wheat uses 0.20 inches/day. Soil type controls how much water can be stored between irrigations — sandy soils hold only 0.75–1.0 inch per foot while clay soils hold 2–2.5 inches. Climate zone affects base evapotranspiration rates — arid regions have higher atmospheric demand than humid ones.
Interpreting the Schedule
The recommended interval is the number of days before soil moisture drops to the refill point (typically 50% depletion of plant-available water). The depth per event is how much water to apply each irrigation. Multiply depth by field area to get total volume needed per irrigation event. Weekly totals help with pump sizing and energy cost estimation.
Adjusting for Rainfall
Subtract effective rainfall from irrigation needs. A 0.5-inch rain event on loam soil saves roughly one irrigation event. Use a rain gauge or weather service data for your location. Automated irrigation controllers with soil moisture sensors can adjust irrigation dynamically when rainfall occurs.
FAQ
Is this irrigation schedule calculator free?
Yes, completely free with no signup. All calculations run locally in your browser.
How much water does corn need per week?
Corn typically needs 1.0–1.5 inches of water per week during peak growth (tasseling and silking). That equals roughly 27,000–40,000 gallons per acre per week. At lower growth stages, demand is about 0.5–0.75 inches per week.
How do I determine irrigation interval for my soil type?
Sandy soils hold less water and require more frequent irrigation (every 2–3 days). Loam soils can go 4–6 days between irrigations. Clay soils hold the most water but drain slowly, needing irrigation every 6–8 days but with risk of waterlogging if over-irrigated.
What is evapotranspiration (ET) and how does it affect irrigation?
Evapotranspiration (ET) is the combined water loss from soil evaporation and plant transpiration. In hot, dry, windy climates, ET can exceed 0.3 inches per day for active crops. Irrigation must replace this water plus any losses to drainage. Arid climate zones have higher ET than humid ones.
Can I use this for drip vs. sprinkler irrigation?
The output shows total water volume needed. Divide by your system's flow rate (gallons per hour for drip, or application rate in inches per hour for sprinklers) to get run time. Drip systems apply water more slowly but are more efficient (90–95% vs 70–80% for sprinklers).