Variable Rate Application on:
[Wikipedia]
[Google]
[Amazon]
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.Grisso, Robert & Alley, Marcus & Thomason, Wade & Holshouser, D & Roberson, O.T.. (2011). Precision farming tools: Variable-rate application. Precision, Geospatial, & Sensor Technologies. 442-505. This is different from uniform application, and can be used to save money (using less product), and lessen the environmental impact.Sawyer, J. E. 1994. Concepts of Variable Rate Technology with Considerations for Fertilizer Application. J. Prod. Agric. 7:195-201.
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
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
Electromagnetic or magnetic induction is the production of an electromotive force (emf) across an electrical conductor in a changing magnetic field.
Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk ...
, which is considered to be cost-effective, and non-destructive.
* ''Sensor based VRA'' is calculated realtime, based on sensors that are local to the variable rate applicator.
Applications of VRA
In precision agriculture, VRA is known to be used in the following areas.Variable Rate Seeding
Planters and drills can be made into VRA sensors, by attaching a motor or gear box. With this, you can vary the rate of the seeds. The seeding rates can also be connected to match the application of agrochemicals.Variable Rate Weed Control
For variable rate weed control you need both a task computer and a system to physically change the flow rate of the agrochemicals.Variable Rate Fertilizer
Crops do not always require a uniform application, as some areas will have different nutrient requirements due to their location (soil properties, sunlight). Variable rate fertilizer spreaders can be used to increase or decrease fertilizer application rate, using aglobal positioning system
The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...
(GPS). They can also use "on-the-go" sensors, or a combination of the two.Saleem, Shoaib Rashid, and Dalhousie University. Department of Agricultural Engineering. ''Variable Rate Fertilization in Wild Blueberry Fields to Improve Crop Productivity and Reduce Environmental Impacts / : By Shoaib Rashid Saleem.'' (2012).
References