Precision irrigation of cotton

Authors: Vories, Earl

Submitted to: University of Missouri Agricultural Experiment Station Publication
Publication Type: Other
Publication Acceptance Date: 8/13/2020
Publication Date: 8/28/2020
Citation: Vories, E.D. 2020. Precision irrigation of cotton. University of Missouri Agricultural Experiment Station Publication. Fisher Delta Research Center 2020 Virtual Field Day, August 28, 2020. Available: https://www.youtube.com/watch?v=-EeCIrqnR-E

Interpretive Summary: Precision irrigation, also known as variable rate irrigation (VRI) or site specific irrigation, is a focus area of the USDA-ARS research program at the Fisher Delta Research Center in Portageville, Missouri. The research objective is to determine what information is needed to create the prescription that controls how the system operates in different portions of the field. While conventional center pivot sprinklers are constantly spraying, variable rate systems use the same sprinklers, but cycle them on and off to get the desired application rate. By measuring the apparent electrical conductivity of the soil and relating it to samples collected and analyzed for texture, it is often possible to accurately map the sand content, which affects the soil’s ability to store water. However, soil texture doesn’t change during the season and may not always reflect the condition of the crop. Infrared thermometers, or IRTs, measure the crop temperature and additional sensors measure the soil moisture content in each management zone. The ARS Irrigation Scheduling Supervisory Control And Data Acquisition (ISSCADA) system combines information from the IRTs, soil moisture sensors, and a nearby weather station and prepares VRI prescriptions. The system can control the pivot and give updates on the status of the irrigation. In addition to the ISSCADA system, mobile sensors measure the normalized difference vegetation index (NDVI), which is related to crop water use, and university cooperators collect data from the field using unmanned aerial vehicles, or UAVs. While the technology for variable rate irrigation is readily available from pivot manufacturers, the goal of the ARS research team is to provide as much information as possible to help farmers take advantage of the technology to make efficient use of water resources.

Technical Abstract: Precision irrigation, also known as variable rate irrigation (VRI) or site specific irrigation, is a focus area of the USDA-ARS research program at the Fisher Delta Research Center in Portageville, Missouri. The research objective is to determine what information is needed to create the prescription that controls how the system operates in different portions of the field. While conventional center pivot sprinklers are constantly spraying, variable rate systems use the same sprinklers, but cycle them on and off to get the desired application rate. By measuring the apparent electrical conductivity of the soil and relating it to samples collected and analyzed for texture, it is often possible to accurately map the sand content, which affects the soil’s ability to store water. However, soil texture doesn’t change during the season and may not always reflect the condition of the crop. Infrared thermometers, or IRTs, measure the crop temperature and additional sensors measure the soil moisture content in each management zone. The ARS Irrigation Scheduling Supervisory Control And Data Acquisition (ISSCADA) system combines information from the IRTs, soil moisture sensors, and a nearby weather station and prepares VRI prescriptions. The system can control the pivot and give updates on the status of the irrigation. In addition to the ISSCADA system, mobile sensors measure the normalized difference vegetation index (NDVI), which is related to crop water use, and university cooperators collect data from the field using unmanned aerial vehicles, or UAVs. While the technology for variable rate irrigation is readily available from pivot manufacturers, the goal of the ARS research team is to provide as much information as possible to help farmers take advantage of the technology to make efficient use of water resources.