Location: Soil and Water Management ResearchTitle: Increasing utility of true TDR soil water sensing systems
|Evett, Steven - Steve
|STROHMEIER, STEFAN - International Centre For Agricultural Research In The Dry Areas (ICARDA)
|HADDAD, MIRA - International Centre For Agricultural Research In The Dry Areas (ICARDA)
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/25/2019
Publication Date: 11/15/2019
Citation: Evett, S.R., Schwartz, R.C., Strohmeier, S., Haddad, M., Schomberg, H.H. 2019. Increasing utility of true TDR soil water sensing systems [abstract]. Third Research Coordination Meeting of the IAEA Coordinated Research Project D1.50.17, October 14-17, 2019, Vienna, Austria.
Technical Abstract: Soil water sensing systems can be used to assess plant water availability and plant water use in watersheds but face problems of accuracy and cost effectiveness that limit their broad applicability. A suite of accurate, low-cost and low-power soil water sensors was introduced, but systems for reading the sensors and sending the data to a central location remained expensive. It was also not known if the sensors could be used to assess plant water use (evapotranspiration, ET). A system of low-cost, solar-powered nodes and gateways was developed and tested in several locations in the USA, the Middle East and Central Asia. A node reads data from several sensors and transmits it to a gateway that can read data from several nodes. Each gateway transmits the data to the Internet Cloud using the locally available cellular telephone network. A network of nodes and gateways can cover a large area relatively inexpensively. Data from a watershed in Jordan and from West Texas illustrate the broad usefulness of the system. Determining ET using soil water sensors depends on the accuracy of the sensors and the ability to measure deeply in the soil to well below the lower limit of the root zone so as to accurately determine change in soil water storage due to plant water uptake. A set of sensors installed at various depths for this purpose is called a sensor profile. At least one profile of sensors is needed to determine the soil water storage. Questions to be answered include how many profiles of sensors are necessary to determine changes of soil water storage accurately enough to determine ET. Three profiles of sensors were installed in a large, precision weighing lysimeter at Bushland, TX, USA, each profile covering the entire 2.3-m depth of the soil monolith. Change in soil water storage recorded using the sensor profiles was compared individually and ensemble with that measured using mass balance using the lysimeter. Solving the soil water balance equation for ET involved adding in daily precipitation and irrigation amounts for a comparison of ET determined using soil water sensing with ET determined by weighing lysimeter.