Irrigation Update: Lower Temps, High Humidity Lead to ET Drop - UNL CropWatch, Aug. 2, 2011

Irrigation Update: Lower Temps, High Humidity Lead to ET Drop - UNL CropWatch, Aug. 2, 2011

August 2, 2011

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Corn at milk stage

(Above) Corn at the milk stage near York August 1. (Photos by Gary Zoubek)

Soybean at R3

Soybeans at the R3 to nearing R4 stage near York August 1.

This is the ninth in a series of weekly podcasts by Exension Educator Gary Zoubek on the use of ETgages and water sensors to improve irrigation management.  Following is an abbreviated summary from the podcast.

Crop ET dropped slightly this past week as temperatures dropped 4-5 degrees and humidity increased 6-8%. The ETgage at Mead dropped 1.40 inches while the ones here in York dropped 1.25 inches for the week. This is slightly down from the 1.5 inch drop last week.

High temperatures for the week varied from 81° F to nearly 94° F and averaged 88° F in York and 90° F at the ARDC. The humidity was up from last week, ranging from 75% to 94% and averaging 85% in York and 81% at the ARDC near Mead. The early planted and later planted corn that we’re monitoring is in the silking/tasseling stage, with some silks starting to turn brown and some almost completely brown.

Due to the high humidity this past week, crop ET for most corn and soybeans was lower than most would expect and averaged between .20 and .22 inch per day.

Soil Watermark sensors in the fields being monitored varied from field to field depending on the rainfall received and whether the fields had been irrigated. All the fields being monitored have been irrigated at least once this season except for one soybean field. Rainfall this past week has varied from .89 inch at the ARDC near Mead to .75 inch at one location in York and .90 inch at the other.

As I mentioned last week, deciding when to irrigate an individual field depends on several factors, including well capacity, the producer’s tolerance for risk, and the weather forecast. I’ve found that it’s always easier to irrigate than it is to not irrigate, especially if your neighbors are irrigating, but is this the best economical and environmental approach?

Our goal in managing our irrigation is to leave some room for potential rainfall while at the same time not limiting potential yields. The better the soils, the more flexibility we have in waiting for that next rain rather than irrigating. That’s why it’s important to know your soil type when using Watermark Sensors. Our recommended trigger for irrigating Hastings silt loam soil is 90 while for the fine sandy loam at the ARDC it’s 50. You can see why knowing your soil type is important to managing your irrigation.

Hear more in the podcast (above) or view the podcast  transcript.

More Information

Careful monitoring of crop water use can lead to fewer irrigations.  Learn more about irrigation management strategies that save water and dollars at

Gary Zoubek
Extension Educator, York County

Catch up with Previous Podcasts

This is the ninth in a series of irrigation management podcasts for eastern Nebraska from Gary Zoubek.  Also see:

Gary Zoubek
Extension Educator, York County


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