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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #320724
Title: Irrigation management using an expert system, soil water potentials, and vegetative indices for spatial applications

Author
item Stone, Kenneth - Ken
item Bauer, Philip
item Sigua, Gilbert

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/24/2015
Publication Date: 6/28/2016
Citation: Stone, K.C., Bauer, P.J., Sigua, G.C. 2016. Irrigation management using an expert system, soil water potentials, and vegetative indices for spatial applications. Transactions of the ASABE. 59(3):941-948.

Interpretive Summary: A variable rate center pivot irrigation system is an irrigation system capable of applying different water depths both in the direction of travel and along the length of the irrigation system. Compared to traditional irrigation systems, these variable rate center pivot irrigation systems require a higher level of management. In this research, our objective was to evaluate and compare three irrigation management methods for their potential in managing variable rate center pivot irrigation systems. The three irrigation management methods were 1) the Irrigator Pro for Corn expert system, 2) using measured soil water potentials, and 3) using remotely sensed crop vegetative indices to estimate crop coefficients. These irrigation treatments were implemented for three years on six soil mapping units. The mean annual corn yields were significantly different each year due to the rainfall during the growing season. However, corn yields for the three irrigation treatments were not significantly different, indicating that each treatment was effective in scheduling irrigations. The mean yearly irrigation depths applied ranged from 7 millimeters (mm) in 2013, 57 mm in 2012, and 156 mm in 2014. The mean water use efficiency was calculated by dividing the corn yields by the total water the crop received (rainfall + irrigation). The water use efficiency over the three years was significantly different with values of 29.8, 16.8, and 23.8 kilograms (kg) grain per hector (ha) per mm of water, for 2012, 2013, and 2014, respectively. For each individual year, the water use efficiency among irrigation treatments was not significantly different. From 2012 to 2014, the Irrigator Pro for Corn and remotely sensed crop vegetative indices treatments managed irrigations as well as the traditional soil water potential based treatment under the VRI system. Each of these irrigation treatments was able to adequately manage irrigation spatially and produce adequate crop yields for the region. Each of these irrigation management treatments could be used effectively to mange irrigations under a variable rate center pivot irrigation system.

Technical Abstract: Variable rate irrigation (VRI) systems are irrigation systems that are capable of applying different water depths both in the direction of travel and along the length of the irrigation system. However, when compared to traditional irrigation systems, VRI systems require a higher level of management. In this research, our objective was to evaluate and compare three irrigation management methods for their potential in managing variable rate irrigation systems. The three irrigation management methods were 1) the Irrigator Pro for Corn expert system, 2) using measured soil water potentials, and 3) using remotely sensed crop vegetative indices (NDVI) to estimate crop coefficients. These irrigation treatments were implemented over six soil types under the VRI system for three years. Corn yields differed among years; average yields were 15.6 Mg ha-1 in 2012, 10.5 Mg ha-1 in 2013, and 13.5 Mg ha-1, in 2014. However, corn yields for the three irrigation treatments were not significantly different for any one year indicating that each treatment was effective in scheduling irrigations. The mean yearly irrigation applied from 2012, 2013, and 2014 varied from 57, 7, and 156 mm, respectively. The mean water use efficiency over the three years was significantly different with values of 29.8, 16.8, and 23.8 kg grain ha-1 mm-1, for 2012, 2013, and 2014, respectively. For each individual year, the water use efficiency among irrigation treatments was not significantly different. For the six soils types, there were no significant differences for corn yield or water use efficiency. The Irrigator Pro for Corn and NDVI treatments managed irrigations as well as the traditional SWP based treatment under the VRI system from 2012 to 2014. Each of these irrigation treatments was able to adequately manage irrigation spatially and produce adequate crop yields for the region. Each of these irrigation management treatments could be used effectively to mange irrigations under a variable rate irrigation system with different management zones.