Done Irrigating? Don’t Forget To Remove Your Soil Moisture Sensors

Done Irrigating? Don’t Forget To Remove Your Soil Moisture Sensors

Removing watermark sensors
Figure 1. Removing Watermark sensors now can help ensure they aren't damaged by harvest and can be used again next year.

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Nebraska growers participating in the Nebraska Ag Water Management Network (NAWMN) use Watermark sensors or ET Gages to provide timely data for irrigation decision-making. If you'd like to help, contact Extension Educator Gary Zoubek, 402-362-5508 or

With most irrigation finished for the season and harvest fast approaching, this is a good time to pull  Watermark sensors and ET Gages and store them for the winter. Taking time now ensures fewer harvest delays and sensors that will be in good working order next spring.

Watermark Sensors

When pulling Watermark sensors be sure to take your time if they don't pull easily. Problems arise most often with the third- or fourth-foot sensors, especially on soil textures with high clay content. Try removing sensors shortly after a rain, adding water, digging down beside the sensor, or using a manufactured puller. Wash off sensors and store them so you'll remember where they are next spring. Heated storage is not necessary as the sensors aren't damaged by freezing temperatures.

When pulling sensors, mark any sensors that have been giving strange readings and may need to be replaced. Also, take note of the location of the sensors. If the area represented the rest of the field well during the year, make plans to install sensors in the same location next spring.  If the numbers didn't match well with moisture conditions over the rest of the field, make a note and try a different location next year.

For those who used a data logger, be sure to download your data to your computer so you can analyze the data this winter.  This can be done by hooking up the data logger to your computer with the included serial cable, or by using an Irrometer WaterGraph Data Shuttle.  One challenge when downloading data is that most computers don't have a serial port, so you will need a USB-to-serial-port adapter to connect to the data logger.  They are readily available online or at computer stores. 

ET Gages

Et Gage covers
Figure 2. Items to check and maintain on your ET Gage: (from left) old style #54 canvas cover; replacement wafer; and new style #54 canvas cover.

If you used an ET Gage to help schedule your irrigation, remember to put it away before the first hard freeze of the year to avoid breaking the ceramic top.  Simply drain any remaining water and store until next spring.

Now would also be a good time to replace the wafer and canvas cover on the ceramic top so your ET Gage is ready to go next spring.  We recommend replacing the wafer and canvas cover every year to ensure accurate readings. If you need more wafers and canvas covers, check with your local NRD if you purchased your ET Gage through them. You may notice that the color of new #54 alfalfa reference covers has changed slightly to a darker green; however, the readings should be similar to those from the old color. 

As with the Watermark sensors, take note of whether the location of your ET Gage gave you good readings over the season.  If not, make plans to try a different location, possibly farther away from trees, obstruction, or tall crops. 

Aaron Nygren, Extension Educator
Gary Zoubek, Extension Educator

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