Role of Global Positioning System (GPS) / Global Navigation Satellite System (GNSS) in Precision Farming

Agriculture is undergoing a revolution with increased producer acceptance of an improved management concept called Precision Farming. Simply stated, precision farming promotes greater yields and reduced input costs by ensuring that the right things are done at the right time at right place and in right amount in the field. Precision farming is a knowledge-based technology. It involves measurement of crop yields such that a coloured map can be generated to show yield variability as a function of field location. These maps can be coupled with soil fertility test results and other information to generate prescriptions which can automatically control the rate at which inputs are applied to a field on a site specific basis. The goal of precision farming is to increase income while reducing environmental impact. Differentially corrected GPS is the backbone of these geo-referenced field operations. In agriculture today, differential correction is provided primarily through AM signals from local beacons and wide-area C-Band or L-Band signals from a geosyncronous satellite. Position accuracies in the range of 1-2 meters (2 sigma) are common in agriculture today and are acceptable for most current operations such as yield mapping, soil sampling, and variable rate application of field inputs. There will be a need, however, for much greater accuracy, in the 5-10 cm range (2 sigma), in the future as GPS is used to automatically steer agricultural vehicles along predefined paths. One of the primary needs of agriculture for the future are new receiver systems that can provide this higher level of accuracy yet are affordable and easy to use. Precision Farming is the future of production agriculture. DGPS will be at the heart of all precision farming applications, and will prove critical to its success. 
 

Agriculture contributes to 2% of the global revenue of GNSS systems, considering the receivers, navigation, maps, and software. Of the four billion GNSS devices used worldwide, Asia-Pacific has the highest contribution, which is higher than both Europe and North America, combined. Miniaturization and improved accuracy of the global navigation satellite system (GNSS) technology (of which, GPS is mostly in use, at present) makes it possible for wide-scale adoption of PF technologies for geo-positioning and field mapping. The scope of GNSS devices in PF includes applications in automatic steering, variable rate application, farm machinery guidance, yield monitoring, biomass monitoring, soil condition monitoring, livestock tracking, and virtual fencing. The market size of GNSS devices includes the scope of tractor guidance, automatic steering, variable rate technologies, and asset management. The tractor guidance segment is the largest contributor, with more than half of the GNSS device’s contribution.

 
Precision agriculture is the ability to manage land by the square meter instead of the square mile. Precision agriculture is changing the farmers relationship with the land. Precision agriculture is an information-based, decision-making agricultural system designed to improve the agricultural process by precisely managing each step to ensure maximum agricultural production and continued sustainability of the natural resources. 

Differential Global Positioning System

DGPS is a technique that corrects for some of the natural and introduced errors common to normal GPS observations, thus improving GPS positions. DGPS corrections can be applied in two ways:

• Post Processing – a technique that requires the GPS user to collect GPS data and then, using specialized software, process the GPS data with DGPS data, collected at the same time, from a known location like a base station or permanent reference station.
• Real Time DGPS – Real time DGPS (R/T DGPS) allows the GPS user to immediately take advantage of differential corrections that are broadcast in real time from DGPS services. The obvious advantage is the immediate improved accuracy that allows for:
• Single visit, time is valuable and costly return trips can be avoided.
• Increased Efficiency: R/T DGPS eliminates post processing and saves money, time and energy.
• Better Results: R/T DGPS provides the capability for accurate mobile mapping.

Geographic Information Systems in agriculture

Geographic Information Systems (GIS) have evolved rapidly within production agriculture especially in the area of precision agriculture. GIS can provide the producer valuable insight into field variability, soil and plant interactions, and yield results. GIS is the most effective information tool the producer has to store, retrieve, map analyze, and manage agricultural data. In many ways, agricultural producers have always been GIS users. Most producers use some type of map for planning what will be done for the coming year. Usually the maps have farm and field boundaries, along with any additional information that the producer might record for helping make decisions. GIS is the link between the field and the office. GIS allows the producer to:

• Compare different types of agriculture data 
• Query to find relationships within and between the data sets
• Produce maps and charts to visualize , interpret and present the analysis results

 

Mobile Mapping for precision farming

Understanding how important information technologies are in precision agriculture, especially GPS and GIS, will provide a real appreciation for mobile mapping. Mobile mapping is the ability to collect field data, with unique geospatial time tags and attributes, for integrating into or updating a GIS. Mobile mapping provides the freedom to collect data anytime, anywhere, in any manner.  It remembers what was recorded, when, and where. Mobile mapping is more than a concept. Like precision agriculture, mobile mapping is a system with individual components.

 
Summary

Much of the ability to implement precision agriculture is based on information technologies; in particular, global positioning and navigation and geospatial mapping and analysis. The foundation for precision agriculture is based on precise locations and time. Fortunately the Global Positioning System (GPS) provides positioning, velocity, and timing capability, and Geographic Information Systems (GIS) provide mapping and analysis capability.