Parker, R.1; Goodson, R2; Henry, Dr Chris3
1CEA-Agriculture, University of Arkansas Division of Agriculture Cooperative Extension Service, Marion, AR, 72364
2CEA-Agriculture, University of Arkansas Division of Agriculture Cooperative Extension Service, Helena, AR, 72342
3Irrigation Specialist, University of Arkansas Division of Agriculture Cooperative Extension Service, Stuttgart, AR, 72160


Irrigation efficiency is a focus in Arkansas. Tools are being added annually. All irrigation scheduling tools have been proven by research.  For this demonstration soil moisture sensors were chosen to meet this need. 

The initial demonstration completed under this program was done using corn.  The objective of this program was to increase irrigation efficiency, by making more informed decisions and using irrigation only when is needed by the crop. Water use measurements were used to determine both water and cost savings using moisture sensors. 

The Corn Irrigation timing and termination demonstration was conducted utilizing Watermark Soil Moisture Sensors placed at depths of 6 in, 12 in, 18 in. and 30 in. The Moisture data was collected via an Agsense telemetry unit.

The data was interpreted to soil moisture balance using the Soil Moisture Sensor Calculator.   The app allows quick assessment of the soil moisture, and with daily sensor readings gives an indication of daily water usage.  From this data, decisions about irrigation timing can be made.  Using this data and a rain forecast, it is possible to delay irrigation events and therefore save dollars.  Also, without the chance of rainfall, irrigation was used to replenish soil moisture.  Decisions to start irrigation was based on a 70 centibar reading from the sensors in the rooting zone.  With this reading, silt loam soil should still have small amounts of moisture available to the plant and not cause stress. 

Irrigation termination was scheduled through the use previously mentioned technology as well as the University of Arkansas “Factsheet for irrigation termination”.  By targeting a full soil profile at maturity R5 growth stage, there was sufficient moisture to complete the crop.

By managing the irrigations against the season rainfall, irrigation events were limited to two times with 2” at each application.   This is compared to an average year where there would be 5 irrigation events applying 3” each time. This translates into a $22.55/ac savings based on a cost of $2.05 an acre inch or water.  With a field size of 66 acres, 19.7 million gallons of water was conserved during the growing season. 

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