Nimisha Gupta, Junior Member-ICT
A global positioning system (GPS) enables the user to determine absolute or relative location of a feature on or above the earth’s surface. Position data is reported in geo-referenced format:
How is GPS used in farming?
Guidance systems base prices are approximately $3,000, including the GPS receiver and a readout unit. Systems that steer the vehicle will be higher priced.
Correction of Errors:
Differential global positioning systems (DGPS) reduce GPS errors and provide more accurate and reliable readings. Differential correction uses a radio signal broadcast from known locations on Earth. These Earth-based stations receive radio signals from the GPS satellites and determine the error from their known positions. The error is calculated and transmitted to the GPS receivers.
Benefits:
- Latitude-Longitude
- State-Plane: It uses simple Cartesian Co-ordinate System and shows 124 geographical zones.
- UTM: The Universal Transversal Mercator System uses a 2-D Cartesian Co-ordinate System and divides earth into sixty zones.
How is GPS used in farming?
- Equipment Guidance System: It includes point guidance which targets point selected on map screen. Cursor location indicates present position; target position highlighted and provides guidance to target. Similar is the process for swath guidance. Light bar-guided and automated steering systems help maintain precise swath-to-swath widths. Guidance systems identify an imaginary A-B starting line, curve or circle for parallel swathing using GPS positions and a control module. The module takes into account the swath width of the implement and then uses GPS to guide machines along parallel, curved, or circular evenly spaced swaths. It has audible tones and indicator lights to make the process simpler for the operator or the farmer.
Guidance systems base prices are approximately $3,000, including the GPS receiver and a readout unit. Systems that steer the vehicle will be higher priced.
- Yield Monitoring System: It basically utilises a mass flow sensor for continuous measuring of the harvested weight of the crop. The sensor is normally located at the top of the clean grain elevator. As the grain is conveyed into the grain tank, it strikes the sensor and the amount of force applied to the sensor represents the recorded yield. While this is happening, the grain is being tested for moisture to adjust the yield value accordingly. The data is displayed on a monitor and a GPS is used to determine the travel speed.
- Field Mapping: GPS technology is used to locate and map regions of fields such as high weed, disease and pest infestations. Rocks, potholes, power lines, tree rows, broken drain tile, poorly drained regions and other landmarks can also be recorded for future reference. GPS is used to locate and map soil sampling (grid sampling and directed sampling) locations, allowing growers to develop contour maps showing fertility variations throughout fields. The various datasets are added as map layers in Geographic Information System (GIS) computer programs.
- Precision Crop Input: GPS technology is used to vary crop inputs throughout a field based on GIS maps or real-time sensing of crop conditions. Variable rate technology requires a GPS receiver, a computer controller, and a regulated drive mechanism mounted on the applicator. Variable rate technology is used to vary fertilizer, seed, herbicide, fungicide and insecticide rates and for adjusting irrigation applications.
Correction of Errors:
Differential global positioning systems (DGPS) reduce GPS errors and provide more accurate and reliable readings. Differential correction uses a radio signal broadcast from known locations on Earth. These Earth-based stations receive radio signals from the GPS satellites and determine the error from their known positions. The error is calculated and transmitted to the GPS receivers.
Benefits:
- GPS guided machines
- Reducing and minimizing spraying
- Reporting on field activity
- Minimizes environmental impacts
- Auto steer