Abstract
Accurate monitoring of soil water status can be an important component of precision irrigation water management. A variety of commercial sensors measure soil water status by relating sensor electrical output to soil water content or soil water potential. However, sensor electrical output can also be affected by soil characteristics other than water content, such as soil texture, salinity, and temperature. This makes it difficult to accurately measure and interpret soil water status without prior on-site calibration. In this study, we investigated the impact of soil texture on the response of three types of sensors commonly used to monitor soil water status, including the Decagon EC-5, the Vegetronix VH400, and the Watermark 200ss granular matrix sensor. A replicated laboratory experiment was conducted to evaluate the response of these types of sensors using four major soil textural classes commonly found in South Carolina. We found that the three types of sensors had a significant response to changes in soil water content, but while the EC-5 and VH400 sensors had a linear response, the Watermark 200ss had a curvilinear response that was explained by an exponential decay function. The response of the three sensor types, however, was significantly affected by soil texture, which will significantly affect the trigger point used to initiate irrigation based on the output from these sensors. Therefore, it is suggested that guidelines on how to use these sensors for local soils need to be developed and made available to farmers, so that they can make better irrigation scheduling decisions.
Highlights
We investigated the impact of soil texture on the response of three types of sensors commonly used to monitor soil water status, including the Decagon EC-5, the Vegetronix VH400, and the Watermark 200ss granular matrix sensor
We found that the three types of sensors had a significant response to changes in soil water content, but while the EC-5 and VH400 sensors had a linear response, the Watermark 200ss had a curvilinear response that was explained by an exponential decay function
The relationships between the sensor outputs and gravimetric volumetric water content (VWC) for each soil type are shown in Figures 6-8, for the EC-5, VH400 and Watermak 200ss sensors, respectively
Summary
Irrigated acreage in South Carolina has been increasing rapidly in recent years. The 2008 Farm and Ranch Irrigation Survey [1] showed that in South Carolina more than 95% of growers, which is much higher than the national average of around 80%, reported using “the condition of the crop” as the primary method of determining when to irrigate. This could lead to waste of significant amounts of water, to increased pumping cost, and to environmental degradation caused by over-irrigation. It could lead to crop stress, reduced crop yields, and lower economic returns caused by under-irrigation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
