The purpose behind VRI is to achieve an optimized soil moisture content in all areas of the field. To achieve this, four things must be done.  

• Variation in water holding capacity (WHC) must be identified by identifying textural variability.
• Textural variability needs to be analyzed and verified to identify the extent of variability.
• Once analysis is complete solution prescriptions (VRI Rx’s) are generated.
• VRI Rx’s are uploaded to center pivot controllers for precision application of water.

VRI stand alone will bring about some improvement but the real profit margin increases come when combining the VRI  (Application System) with the sensor (Scheduling System)

By identifying weather and atmospheric changes around the field, irrigation applications can be adjusted to account for these changes making sure the plants in the field are allowed to grow and produce with limited stress. Limiting stress will allow for greater plant health.  Optimized soil moisture content also aids in the uptake of nutrients from the root zone profile. Therefore healthy plants pulling in a higher percentage of available nutrients will produce a bigger yield to further improve profit margins. 

VRI may exist in either a Speed Control format (only pivot speed is addressed) or a Zone/Nozzle control format (pivot speed and nozzles are controlled).  Analysis can be done for both options to look at the improvement that both will provide.

In most cases, computer panels are not a requirement for Variable Rate Speed Control.