@article{Hedley:149789,
      recid = {149789},
      author = {Hedley, Carolyn and Bradbury, Stu and Watson, Eric and  Dalrymple, Hew and Wright, John},
      title = {Farm scale trials of variable rate irrigation to assess  the benefits of modifying existing sprinkler systems for  precision application},
      journal = {International Journal of Agricultural Management},
      address = {2011},
      number = {1029-2016-82239},
      pages = {5},
      year = {2011},
      abstract = {Farm-scale trials are being conducted to assess the  benefits of variable rate irrigation (VRI). Three farms  have been selected where existing sprinkler irrigation  systems have recently been modified to provide variable  rate control of each individual sprinkler. Irrigation is  being varied according to soil and crop differences, and is  also being shut off over exclusion zones, such as drains  and raceways, and for farm operations such as pasture  renovation. 
Under each VRI irrigator, soil variability has  been quantitatively assessed using a mobile soil mapping  system, which consists of an electromagnetic (EM) sensor  pulled behind an all-terrain vehicle, with an on-board  accurate RTK-GPS, datalogger and field computer. The EM  sensor measures soil apparent electrical conductivity (EC),  and the resulting soil EC maps were ground-truthed and used  to define irrigation management zones. Soil moisture  sensors have been installed into each zone to monitor  real-time soil moisture status. This information is then  used for variable rate irrigation scheduling. 
Trial plots  have been established in each zone at each site to compare   a blanket uniform rate of irrigation to all zones with  variable rates of irrigation fine-tuned to zone  differences. 
A goal of this research is to assess  irrigation water use efficiency of a VRI system, as well as  to develop a precision irrigation system with capability  for full automation.},
      url = {http://ageconsearch.umn.edu/record/149789},
      doi = {https://doi.org/10.22004/ag.econ.149789},
}