Chapter 12

Variable-Rate Technology in Precision Agriculture

Variable-Rate Seeding Technology

Variable rate seeding (VRS) is a precise agricultural technology that can accurately and adequately adjust the seeding rate according to the variability of soil properties, terrain, meteorological conditions, and other factors. VRS not only provides better opportunities for the use of variable soil nutrient and water storage capacity characteristics, but it can also increase crop yields by reducing seed consumption. Seed germination, crop development, and yield potential may vary in different areas of a field. Thus, VRS is a method of linking seed quantities to a specific location, thereby increasing crop yields and production profits.

Planter Operation

Variable-rate seeding can be achieved with varying levels of granularity, ranging from a whole-planter variable rate to individual row-unit control. With the introduction of hydraulic drive seed meters and electric drive meters, it is possible to control the seeding rate independent of the ground speed. Hydraulic drives are operated at high rotational speeds with speed reduction at each seed meter, whereas electronic drives operate at much lower rotational speeds due to the “direct drive” nature of the mechanism. A major drawback of hydraulic drives when compared to newer electric drives is the additional complexity of the system, with more “wear parts” and service/maintenance requirements. Electric drives are generally less expensive than hydraulic drives.

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