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Irrigation, Soil & Fertility TimingSoil Moisture Monitoring Calendar
Checking soil moisture on a regular schedule turns watering from a guess into a decision. The tools range from a trowel to buried sensors, and the routine matters more than the gadget.
Key points
- Soil moisture readings show what the crop can actually use.
- Hand checks are free and effective with practice.
- Place sensors in a representative spot in the root zone.
- Check more often in heat and dry spells.
- Use thresholds from your state's irrigation guide.
Why monitor soil moisture at all?
Weather forecasts and rainfall totals tell you what fell, not what is available to the crop. Soil moisture readings show how much water is actually in the root zone, which is the number that matters for irrigation timing and for judging stress.
Monitoring also helps you avoid over-watering, which wastes water and energy and can leach nutrients or promote disease.
Even a rough routine, such as checking each field after every rain and every week in summer, gives you far more information than most growers collect. Start simple and add tools as the habit grows.
What are the simple methods?
The feel method is the oldest: dig down to root depth, squeeze a handful of soil, and judge it by how it holds together and how it feels. Extension publications show how to read this for different soil textures. It is free and fast, and it improves with practice.
A probe or soil auger helps you reach depth without a lot of digging, and a long screwdriver pushed into the soil can show where it becomes hard or dry.
Practice on a day when you know the answer, such as right after irrigation, so your hands learn what wet soil feels like in each texture.
- Check at more than one depth.
- Check more than one spot in each field or bed.
- Compare readings to what you see in the crop.
What about sensors and meters?
Tensiometers, resistance blocks and electronic sensors measure how tightly water is held in the soil or how much is present. Kansas State, Wyoming and UMass extension publications explain how these tools work and how to place them.
Sensors need correct installation, good contact with soil and regular checking, and readings must be interpreted for your soil type. Ask your extension office about thresholds that fit your crop and soil.
How should you place and read monitors?
Place sensors in the active root zone and, if you can, a second sensor deeper to see whether water is moving below the roots. Put them in a representative spot, not in the wettest or driest corner, and not next to an emitter or sprinkler head unless that is what you intend to measure.
Take readings at the same time of day, and record them in a log or chart so you can see trends, not just single numbers.
Different soil textures hold water differently, so a reading that is dry in sand may be fine in clay. Learn the thresholds for your soil type rather than copying numbers from another farm.
How does a monitoring calendar work through the season?
Early in the season, check weekly or after significant rain, mainly to learn how your soil behaves. As crops grow and water use rises, check more often, and during heat waves or dry spells check as often as every day or two for sensitive crops.
Later, as crops mature and demand drops, you can space checks out again. Record the date of your last irrigation or rain beside each reading.
What mistakes should you avoid?
Relying on surface appearance, using a single sensor for a varied field, skipping calibration steps and ignoring readings are common mistakes. Another is trusting a reading without confirming with a dig, particularly when something looks off.
Sensor failures happen, so cross-check with the feel method now and then.
Keep spare batteries, replace damaged cables and clear vegetation around installed sensors, so a failure does not leave you blind during the dry spell when you need the data.
How do you turn readings into decisions?
Use thresholds from your state's irrigation guide for your crop and soil. When readings fall to the threshold, irrigate. When they stay above, wait. Adjust for the forecast and the crop stage.
Keep the log from year to year. Over several seasons, it will show how quickly your soil dries in different weather and help you pick better irrigation dates.
Sources and further reading
Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.