Variable Rate Irrigation

There is increasing pressure on our water resources, which prompts us to manage our water more precisely. With an increasing demand for food production, variable rate irrigation (VRI) is a technology that may improve water use efficiency, defined here as the ratio of yield to the depth of water pumped for irrigation. While VRI is not likely to reduce the consumptive use of water (i.e. evapotranspiration), VRI may reduce pumping, resulting in energy savings and improved water quality (due to reduced deep percolation). VRI has many potential applications, and the specific benefits of each application should be quantified in order to inform producers who are considering investing in VRI technology. Research is also needed to develop a decision support system that would automate the process of making dynamic irrigation prescription maps for VRI management.

Past research includes a statewide analysis of potential pumping reductions from VRI (Lo et al., 2016), a method for field characterization of root zone available water capacity (Lo et al., 2017), an economic framework for decisions about whether to invest in VRI (chapter 1 of Lo, 2015), a method for making  irrigation prescription maps based on soil properties (Barker et al., 2016), an evaluation of control scenarios for prescription maps (Miller et al., 2017), and an analysis of the number of soil water monitoring locations required for VRI management zones (Barker et al., 2017a). Ongoing research is determining prescription maps and spatial variability in ET based on remote sensing imagery from satellites and unmanned aircraft (Barker et al. 2017b; Barker et al., 2017c).

Map for VRI Pumping Reduction

This map tool provides an estimate of pumping reduction from using VRI to mine undepleted soil water.

Refereed Journal Articles

  • Barker, J. B., D. M. Heeren, C. M. U. Neale, and D. R. Rudnick. 2017c. Response of maize and soybean to variable rate irrigation using soil water content monitoring and a remote-sensing-based water balance model. Agricultural Water Management (aceepted).
  • Barker, J. B., C. M. U. Neale, D. M. Heeren, and A. E. Suyker. 2017b. Evaluation of a hybrid reflectance-based crop coefficient and energy balance evapotranspiration model for irrigation management. Transactions of the ASABE (in press).
  • Barker, J. B., T. E. Franz, D. M. Heeren, C. M. U. Neale, and J. D. Luck. 2017a. Soil water content monitoring for irrigation management: A geostatistical analysis. Agricultural Water Management 188: 36-49, doi: 10.1016/j.agwat.2017.03.024.
  • Lo, T., D. M. Heeren, L. Mateos, J. D. Luck, D. L. Martin, K. A. Miller, J. B. Barker, and T. M. Shaver. 2017. Field characterization of field capacity and root zone available water capacity for variable rate irrigation. Applied Engineering in Agriculture 33(4): 559-572, doi: 10.13031/aea.11963.
  • Lo, T., D. M. Heeren, D. L. Martin, L. Mateos, J. D. Luck, and D. E. Eisenhauer. 2016. Pumpage reduction by using variable rate irrigation to mine undepleted soil water. Transactions of the ASABE 59(5): 1285-1298, doi: 10.13031/trans.59.11773.
  • Miller, K. A., J. D. Luck, D. M. Heeren, T. Lo, D. L. Martin, and J. B. Barker. 2017. A geospatial variable rate irrigation control scenario evaluation methodology based on mining root zone available water capacity. Precision Agriculture (in review).
  • Finkenbiner, C. E., T. E. Franz, J. Gibson, D. M. Heeren, and J. D. Luck. 2017. Integration of hydrogeophysical datasets for improved water resource management in irrigated systems. Precision Agriculture (in review).

Other Relevant Products

Links

  • News video: Burdette Barker receives University of Nebraska Presidential Fellowship for VRI research
  • News video: Dr. Wayne Woldt flies unmanned aircraft to inform VRI management
  • Extension publication on VRI