Does your local service provider have experience installing VRI systems?
I have been involved with the setup of four different VRI systems as part of several research projects. Three of the four fields had some significant problems with the installation. After installation, insist that the service provider demonstrate that the system works and provide documentation on the sprinkler bank locations. Verifying both of these things will prevent many headaches later on.
Do you have a variable frequency drive?
VRI changes the pivot’s flow rate as it moves around the field, and these dips in flow are an opportunity to save energy. The VFD will cut back the motor’s speed to take advantage of the lower flow requirement. If pumping with electricity, install a VFD to realize the most energy savings.
Does your field have enough variability to justify VRI?
This is probably the most difficult question to answer. Bob Evans, formerly with the USDA Agricultural Research Service, did a survey of VRI literature in 2013. He found that water savings from VRI typically ranged from 5 to 15 percent. These savings are relatively modest when considering that the cost of a VRI system can range from $15,000 to $30,000, depending on the pivot size. However, 5 to 15 percent can add up quickly when considering fertigation.
Most VRI research to date focused on hardware aspects, but recently more management-focused experiments have emerged. Some of these studies examined the savings potential of dynamically controlled VRI systems, and the results look promising. The biggest obstacle to using dynamic VRI is the burden of managing all that information. As agricultural information technology develops, VRI has the potential to become a central component in precision irrigation management.
Charles Hillyer, PhD, is the assistant profes- sor and extension specialist of irrigation engineering at the University of Texas A&M AgriLife Extension Service at Amarillo.
irrigationtoday.org 15
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44
