NDSU Ag Engineer Says Precision Ag
Technology Can Boost Management and Returns
By Vern Hofman, Power
and Machinery Specialist
NDSU Extension Service
Despite its initial cost, precision
farming has excellent potential to help farmers improve management and
economic returns says a North Dakota
State University agricultural
engineer.
"Variable rate application has become
feasible due to several new technologies including fast computers and
powerful graphical and informal management software," says Vern Hofman of the NDSU Extension Service. "These
technologies are now small enough to be easily carried in a tractor
cab."
That technology allows producers to
cut costs in new ways, Hofman notes. "Instead of
making fields larger to reduce costs, precision farming will allow farmers
to apply crop inputs to individual parts of a field while using large
machinery."
Hofman has been using yield monitoring technology in
his precision agriculture studies for six years. "It is an excellent way
to determine crop variability," he says. "If a producer is thinking of
moving into precision farming, a yield monitor may be one of the best
places to start. It is advisable to collect yield data over three or four
years to see trends occurring in a field. If low yields are consistently
showing up in an area, can you make changes to improve the production
capabilities? If you are losing money, should something else be
done?"
The first step toward applying inputs
at variable rates is to do regional soil sampling to provide data about
the variation in soil conditions throughout the field. Once the soil type
is determined and a projected yield is set, the data can be processed into
maps to provide information for variable rate controlling devices. "All
areas of a field can have different amounts of inputs including
fertilizer, seed, and pesticide application done based on its production
capabilities or needs," Hofman explains.
.
Once this prescription map has been
developed, it must be executed by an application implement. A
differentially corrected GPS receiver determines implement position in a
field. The GPS receiver is coupled with a computer in the tractor cab that
determines fertilizer and seed rates based on the position. The computer
operates application rate controllers that are connected to the computer
and adjusted for the implements they control and calibrated for the
materials it will apply.
"After that, it is usually a matter of
turning on the electronics, selecting the application map for the field
from a menu and proceeding down the field," Hofman says. Information on position in field and rate
of application are usually displayed on the console in the
cab.
They key components of a variable-rate
application system are:
- GPS Receiver. Mounted on the tractor cab, the
GPS receiver takes signals from satellites to determine the application
unit position.
- GIS Map Reading Software. Geographical
information system (GIS) software installed in a computer reads a
GPS-linked prescription map that is prepared in advance, usually from
soil test information obtained from the field regions.
- Computer and Electronic Control. Mounted in a
tractor cab, this unit operates the software and controls the metering
unit speed. Controller units may use a variable speed electric motor or
a hydraulic motor.
- Metering System. Usually driven by the
tractor’s hydraulic or electrical system, this motor delivers a specific
amount of material (fertilizer, seed or pesticide) per revolution. Motor
speed is controlled electronically from the cab and thus material volume
can be controlled. A system must be calibrated to determine the amount
of fertilizer, metered per revolution. This is done by operating the
motor for a period of time, the weight is determined and then the amount
is compared to the desired amount. Adjustments are made and the planting
begins.
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