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Field Crops, Grains & OilseedsField Crop Irrigation Scheduling Calendar
An irrigation calendar works best when it is built on soil moisture and crop stage, not on the same number of days between watering every year.
Key points
- Schedule irrigation by soil moisture, crop stage and weather, not a fixed interval.
- Know which growth stages are most sensitive to water stress for each crop.
- Track soil moisture at several depths and keep a rain gauge.
- Soil type and root depth change how often and how much you irrigate.
- Follow local water rules and keep records.
What does irrigation scheduling mean?
Irrigation scheduling is deciding when to irrigate and how much to apply, based on soil moisture, crop water use and weather. Extension programs commonly describe it as a water budget: what the crop uses, what rain supplies and what the soil can store.
A written plan helps you use water efficiently and avoid stress during sensitive stages. Local water rules, rights and restrictions apply, so check yours before planning.
Even if you rely only on rain, the same water budget idea helps. Tracking rainfall against crop water use tells you when a dry spell is turning into a problem.
Which growth stages are most sensitive to water stress?
Many crops have stages where water stress costs the most yield. In corn, the period around tasseling and silking is widely described as sensitive. In soybeans, flowering through seed fill is a sensitive period. Small grains are sensitive around boot, heading and early grain fill.
Ask your extension office for the stages that matter most for each crop in your area, and plan so that water is available then.
Water stress at those stages can reduce kernel set, pod set or seed size, which is why extension programs focus on them when water is limited.
How do you track soil moisture?
Common tools include soil moisture sensors, the feel method, and a checkbook approach that adds rainfall and irrigation and subtracts crop water use. Extension programs often publish crop water use data and tools for your region.
Check moisture at several depths where roots are active. Compare sensor readings with a spade check from time to time to confirm they make sense.
- Use sensors or the feel method at several depths
- Track rainfall with a gauge in or near the field
- Log irrigation amounts by field
- Check crop water use data from extension
How do soil type and root depth affect timing?
Sandy soils hold less water and need more frequent, lighter irrigation. Clay and loam soils store more but release it more slowly. Young crops with shallow roots are more sensitive to short dry spells than established crops.
Know your soil water holding capacity for each field, and ask your NRCS office or extension agent how to find it.
Compaction layers and shallow soils can restrict roots, so dig a few holes and see how deep roots actually reach before you decide on your schedule.
How do weather and forecasts fit in?
Heat, wind, humidity and sunshine change crop water use, and rain can replace an irrigation. Use the National Weather Service forecast and local weather station data. The U.S. Drought Monitor shows regional conditions.
Avoid irrigating just before a forecast rain if you can, and avoid irrigating in conditions that waste water through wind drift or evaporation.
Equipment checks matter as well. Uneven pressure, clogged nozzles and leaks waste water, so inspect systems before the season and during it.
How should you handle limited water?
If water is limited by allocation, well capacity or restrictions, decide in advance which fields and growth stages get priority. Extension programs discuss deficit strategies for some crops, but the economics depend on your area.
Talk with your irrigation district, extension office and crop adviser. Keep written records of water use for your own planning and for any reporting your area requires.
How do you build a simple irrigation calendar?
Start with the date the crop emerges and the stages when water is most important. Add rows for expected crop water use by period, based on extension data, then mark how much water the soil can store and when you will check it.
Update the calendar with real rainfall and irrigation as the season goes. A plan that changes with the weather is better than a fixed schedule. Review the calendar with your extension office or irrigation adviser at least once each year.
Remember to include pump, well and system maintenance dates, since a breakdown during a sensitive stage costs far more than a service call beforehand. Record date, field, hours or amount applied, rainfall, soil moisture readings and crop stage. Add notes on problems such as pressure or clogged nozzles. Review the records after the season and compare yield to water use so you can improve next year's plan.
Sources and further reading
Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.