Variable Rate Technology


 All areas of a field are not equal in soil type, moisture holding capacity, fertility, field traffic patterns or topography. Due to these differences, a field will not be able to produce the same germination rate or support the same final plant population across its entire acreage. Variable rate technology has made it possible for producers to specifically determine the planting rate, fertilizer needs, and irrigation requirements on each area of their fields to optimize yield and quality.


Variable-Rate Seeding:

Fields with a high range of soil variability, determined by soil samples, can benefit from variable-rate seeding. This practice uses planters with hydraulic drives necessary to change seeding rates based on yield potential of different management zones.


Research done using variable-rate seeding has shown higher returns come from avoiding high populations in areas where high populations decreased yields, as well as higher yields from more productive areas with higher-than-normal seeding rates.

Links relating to VRS:

Farm Basics Video: Variable Rate Planting



Variable-Rate Fertility:

Variable Rate Fertility utilizes technology to understand the production capabilities of different areas of a field and then adjusts the amount of fertilizer applied to optimize yield and quality. Variable-rate fertilizer application allows crop producers to apply different rates of fertilizer at each location across fields. The technology needed to accomplish variable-rate fertilization includes an in-cab computer and software with a field zone application map, fertilizer equipment capable of changing rates during operation and the Global Positioning System (GPS). The fertilizer rate at specific locations within fields is based on the georeferenced field zone map on the in-cab computer. The system includes a vehicle-mounted GPS unit to monitor field locations, allowing the computer to change the application rate between zones. Electronic communication between the in-cab computer and the rate controller on the application machine functions to change the fertilizer rate across the field.


Variable-Rate Irrigation:

The goal of variable-rate irrigation is to determine the optimal amount of water depending on variations in a field’s water holding capacity in both surface and sub-surface soils. By determining field specific water needs, producers can avoid applying excess irrigation leading to unnecessary costs and leaching nitrogen, potentially lowering yields, as well as applying too little irrigation, also decreasing yield potential. To meet each section of the field’s water needs, irrigation rate and timing may be increased or decreased based upon the variable-rate irrigation prescription determined by technology offered by commercial dealers.

Links relating to VRI:

CropMetrics Virtual Agronomist

Valley Irrigation VRI  - Video