SOIL MOISTURE SENSING
THE VALUE PROPOSITION OF SOIL MOISTURE SENSORS IS FAR BEYOND THEIR ROLE IN AVOIDING OVER-IRRIGATION.
benefits of sensors are considered when evaluating ROI. These more obvious benefits are avoiding over-irrigation and thus conserving water resources and reducing energy costs associated with extracting, conveying and applying water. In our field evaluations across Oklahoma we have encountered fields that were consistently under-irrigated even though water availability was not an issue. Use of soil moisture sensors can help avoid yield losses due to under-irrigation.
We have also observed fields that receive small, frequent irrigations, which leads to a larger portion of applied water evaporating from soil and crop surfaces and thus not being available in the deeper soil layers to be extracted by roots later. This practice can also result in shallow root systems that cannot extract water (and nutrients) from deeper layers. In other areas where irrigation capacity is limited
due to natural reasons or consumption caps, sensors can help optimize deficit irrigation management to minimize yield losses. For example, sensor readings can be used to cut back on irrigation during less sensitive growth stages to preserve limited irrigation water for more sensitive growth stages. The value proposition of soil moisture sensors is far beyond their role in avoiding over-irrigation. They can be used to control and manage water fluxes in a fashion that would maximize water and nutrient uptake efficiency and, consequently, farm profitability — especially when water is short.
The second opportunity for growers is to test existing and new sensors and provide feedback to sensor manufacturers, researchers and extension specialists on the positive and negative aspects of the new sensors. This requires time and resources on the part of growers
Soil moisture sensors are used to apply different levels of irrigation at this Oklahoma State University research field. Different shades of green show strips of cotton under variable degrees of water stress.
and provides no immediate benefits to them, but it is crucial in addressing the shortcomings of sensors and brainstorming solutions to improve this technology. Without direct input from intended users of the technology, it is difficult (if not impossible) to identify and fix issues.
Policymaker support
Finally, the opportunities for policymakers at local, state and federal levels are to support applied research and extension projects by universities to facilitate testing and demonstrating the use of sensors. With a considerable number of new sensors or models being introduced to the market each year, there is a need to assess the accuracy, reliability and user-friendliness of these sensors at research stations or commercial farms in collaboration with partnering growers. Once the sensors are tested and verified, supportive policies and financial incentives can help increase their adoption by reducing the financial risk of investing in these technologies. The incentives offered to growers should be widely available and commensurate with the costs of sensors and accessories.
Saleh Taghvaeian, PhD, is an associate professor and extension specialist in agricultural water management at the department of biosystems and agricultural engineering at Oklahoma State University.
A soil moisture probe is installed in an irrigated chili pepper field in west-central Oklahoma. 26 Irrigation TODAY | Summer 2021
The products shown in this article are provided as examples only and are not endorsed by the author.
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