By Cale Cloud, University of Georgia Extension
The overall goal of the University of Georgia’s (UGA) Agricultural Water Efficiency Team (AgWET) project is to help farmers schedule irrigation or to give them a better understanding of why they may need to use these tools to help schedule their irrigation. The three-phase project will also increase the producers’ water use efficiency through the use of soil moisture sensors and smartphone apps.
Two years ago, Dr. Laura Perry Johnson, University of Georgia Cooperative Extension Associate Dean, initiated Phase I of the AgWET project with two objectives: train county Extension agents on advanced irrigation scheduling tools and have the trained agents transfer that knowledge to two growers in their county and provide the growers with scheduling tools to deploy in a center-pivot irrigation field.
The agents worked with the growers to utilize the tools to schedule irrigation in the fields and compare results with the grower’s standard method of irrigating.
Two irrigation scheduling tools were selected. The first was the SmartIrrigation Cotton App for Android and Apple smartphones that was developed by University of Georgia precision ag expert George Vellidis (www.smartirrigationapps.org). The Cotton App uses an evapotranspiration (ET)-based model to estimate when irrigation is necessary and provides the user with an estimate of how much water should be applied. It does not require any sensors, sends the user notifications when action is needed and is currently available at no cost. The only disadvantage is that requires accurate daily precipitation data to perform optimally.
The second tool was the Trellis soil moisture sensing system (https://mytrellis.com). It consisted of three probes and wireless telemetry so that the data could be viewed online from any internet-capable device. The three probes, each with two soil moisture sensors (at 6 and 14 inches), were installed in different soil or topographic types in each field to demonstrate the in-field variability that exists. This also helps agents and growers learn about how to use the variability to make better scheduling decisions.
For example, if the sandy area of the field is drying quickly but the majority of the field is not, how do you decide when to irrigate? In contrast, if a topographically lower portion of the field is staying consistently wet, what irrigation strategy do you adopt?
The advantages of the soil moisture sensing system is that it directly measures soil moisture in the field, which provide growers with more confidence than ET-based models. Its disadvantages are its expense, has recurring costs, requires installation after planting and removal prior to harvest, and each sensor only measures soil moisture in a narrow radius around the probe.
Both the SmartIrrigation Cotton App and the soil moisture sensing system were used in all of the fields to educate county agents and growers on the advantages and disadvantages of both irrigation scheduling tools.
In 2018, we began Phase 2 of AgWET. The biggest additions to Phase 2 were adding four additional counties to the five that were active the previous year. There were also some social science activities incorporated into this phase such as surveys, focus groups and interviews. This was done in order to learn county agent and farmer beliefs and opinions or behavioral changes related to perception and adoption of the tool — before and after the project.
Fast forward to 2019, and we are in Phase 3 of AgWet. This year, UGA Extension is partnering with the Flint River Soil and Water Conservation District (FRSWCD). UGA Extension received funding from the Lower Flint-Ochlocknee and Upper Flint Regional Water Councils to carry out this project for the next two years.
The counties highlighted in red as seen in Figure 1 will be using the SmartIrrigation Cotton App to help farmers schedule irrigation just as we did in Phases 1 and 2 of AgWet. The cotton soil moisture probes are equipped with two sensors, one at 6 inches and the other at 14 inches.
FRSWCD received funding from the Southeast Aquatic Resources Partnership (SARP) and the National Fish and Wildlife Foundation to carry out their side of the project. This project is to be carried out for the next three years. FRSWCD’s location of this project expands outside of southwest Georgia and goes into southeast Alabama and north Florida as well, staying within the Apalachicola-Chattahoochee-Flint River Basin (ACF) area.
The counties highlighted in blue in Figure 1 will be using the Irrigator Pro irrigation scheduling app for peanuts. Irrigator Pro is an irrigation scheduling tool for peanuts, corn, and cotton developed by the United States Department of Agriculture Agricultural Research Service National Peanut Research Lab. Irrigator Pro is an expert system designed to provide recommendations based on scientific data resulting in conservation-minded irrigation management while maintaining high yields. Unlike the UGA Extension portion of the project, the FRSWCD side with peanuts only uses 1 soil moisture probe per field instead of 3. Also, each of these probes is equipped with 3 sensors instead of 2. They are located at depths of 8 inches, 16 inches and 24 inches and are also equipped with a soil thermometer.
There is also a rain gauge attached with each sensor station, as seen in Figure 2. The Irrigator Pro app collects soil moisture sensor data and temperature data wirelessly through the cloud from the Trellis probe and the data is then sent to Irrigator Pro. The app will issue an irrigation recommendation based on the soil moisture readings and crop development stage.
Finally, in the counties that are highlighted in green, those Extension agents will work with farmers in both peanut and cotton using both the SmartIrrigation Cotton App and the Irrigator Pro app. Aside from the numerous county agents that are working with us throughout the project area, we also have three crop consultants participating as well. We have one group located in central Georgia around the Dooly and Houston county area, one in Early County and one in Terrell and Lee Counties.
Although the soil moisture systems will cost the farmer money to buy, these two smartphone apps are free to download and use through the Apple Store or the Google Play (previously Android Market) Store. Irrigator Pro is also available to download on PC, but the SmartIrrigation Cotton App is for iOS and Android smartphones only.
Screenshots from the Smart Irrigation Cotton App.