In precision agriculture, variable rate application (VRA) refers to the application of a material, such that the rate of application is based on the precise location, or qualities of the area that the material is being applied to.[1] This is different from uniform application, and can be used to save money (using less product), and lessen the environmental impact.[2]
Variable rate application can be either map based or sensor based.
Map based VRA is pre-planned, and applications are based on VRA prescription maps that an agronomist or advisor prepares based on data sources. Prescription maps can be created using electromagnetic induction, which is considered to be cost-effective, and non-destructive.[4]
Sensor based VRA is calculated realtime, based on sensors that are local to the variable rate applicator.
^Grisso, Robert & Alley, Marcus & Thomason, Wade & Holshouser, D & Roberson, O.T.. (2011). Precision farming tools: Variable-rate application. Precision, Geospatial, & Sensor Technologies. 442-505.
^Sawyer, J. E. 1994. Concepts of Variable Rate Technology with Considerations for Fertilizer Application. J. Prod. Agric. 7:195-201.
^Khan, Fahad Sarwa, and Dalhousie University. Department of Engineering. Mapping Soil Properties and Water Table Depths Using Electromagnetic Induction Methods (2012).