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P/N 1600043 Rev M (ECN 34095) 1 VRI Installation Manual
VRI Installation
Introduction
What is Variable Rate Irrigation?
Variable Rate Irrigation (VRI) is a controller added to a mechanized irrigation system. This controller regulates the
amount of water to be applied along any part of the irrigator path.
Past irrigation practices attempted to maximize efficiency using blanket irrigation, where water is applied as
uniform as possible under the length of irrigator. This has not been found to be the most efficient way to irrigate
by today’s standards. Variables such as drainage, soil texture and type, different crop requirements, and in some
cases, several acres within a field would require no watering at all but still lie in the irrigator’s path; all of these situ
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ations can produce undesired results with blanket irrigation.
With Variable Rate Irrigation, the correct quantity of water can be applied in the precise location where it’s needed.
How Variable Rate Irrigation works
VRI provides precision control of all sprinklers on a center pivot irrigation system by pulsing each individual sprin-
kler on and off. This allows the application rate to be modified along the entire length of the system.
First, a map of the field to be irrigated is uploaded to the VRI program. This can either be drawn in from aerial pho
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tographs (such as Google Maps), using soil maps, or from points that have been recorded using a handheld GPS.
From the images, “management area boundaries” can be created, where specified zones needing less water can
be marked.
Next, the amount of water to be applied to each area must be defined. The VRI software allows the operator to
establish this application amount and program it into the system for each established “irrigation zone”. Once the
design is completed, the operator must upload the VRI program to the controller at the center pivot. (USB “Thumb
Drives” are the typical method of file transfer.)
Each sprinkler has a latching solenoid valve that is pulsed on or off by a controlling node. Each node controls four
sprinklers with individual control of each valve.