Oliver Hargreaves, Alfonso Torres-Rua, Niel Allen, Matt Yost, Lawrence Hipps, David Stevens, Rui Gao, Karem Meza-Capcha, Laura Christiansen
Description
Crop water consumption, or evapotranspiration (ET), is a key metric in managing crops and water use and in quantifying agricultural production efficiency. Determining ET accurately is difficult and requires using expensive instruments such as lysimeters or eddy covariance (EC) towers. However, such equipment is cost prohibitive for most land managers and is reasonable only in research settings. This project aims to calculate ET from measurements of the soil water balance, namely changes in soil water storage using only soil moisture sensor data for an irrigated crop. This approach would make ET information accessible to a larger number of managers and producers for better-informed decision making. Six soil moisture depletion methods with different approaches and varying degrees of complexity were developed and tested on two agricultural sites in Utah. The first site, dedicated to alfalfa production and equipped with an EC tower, is located in Vernal. The second site, dedicated to onion production in two fields under two different irrigation technologies, is located in West Weber. The results from the six soil depletion methods tested at the Vernal site were compared to the EC tower results to evaluate the accuracy of all the methods. The results from the soil depletion methods from the two fields in West Weber were compared using statistical analysis to assess the difference in crop water use due to different irrigation technologies.
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