Precision Agriculture     Justin Abel, Dane Boring, and Alex Hajek-Jones

Overview:

A wide variety of system technologies are available in assisting farm operations in managing their soils. All of these systems are equipped with GPS capabilities in order to spatially reference where they are located in the field. Location is a significant factor involving application of fertilizers and chemicals in reference to soil maps discussed previously. By pinpointing the exact location of a machine in the field, a very precise application can be achieved that is within a sub-meter. Without spatial information, precision agriculture and associated technologies would not be possible.

 

Most precision technologies are not only used for application purposes, but also to create a more comfortable environment for farmers operating the machines. Most farmers spend their time out in the field from sunlight to sundown, which can lead to physical fatigue. By allowing the machine to conduct more of the work, the operator is relieved from much of the stress associated.

 

Here is a list of SSCM (Site Specific Crop Management) developments to help give a clearer image of what the assimilation of GIS and GPS technologies are capable of doing together.

 

Satellite Guidance: Uses satellites in a real-time setting to navigate farm equipment on an accurate path that is preset by the operator through an onboard computer system.

 

Hydraulic Auto Steer: A complex hydraulic system which functions in conjunction to the computer and GPS unit. This system is fixed directly into the steering which is automated and guides itself on a linear path programmed by the driver. The operation of this is generally hands free until the machine reaches the end of the field. The driver must then disengage the system and manually turn the machine around where he/she then reengages it to resume its linear path across the field.

 

Mechanical Auto Steer: This system performs much like its hydraulic comparative, though it is not a permanent fixture. A bracket fixed around the existing steering column holds in place a mechanical pilot which can be removed as needed to be used in other machines fastened with similar brackets. This system works on a guided linear path just as well, requiring operator assistance upon reaching the end of the field.

 

Parallel Tracking: A simple light bar navigation system used to keep the machine on a regulated linear track parallel to past applications. Unlike the previous steering methods, this one is not at all hands free. The operator must steer the machine manually while receiving guided path information as indicated by the light bar. A light displayed on screen represents the machines center line. If the light strays from center, the operator must compensate by steering the machine back to center.

 

 

 

 

 

 

 

 

 

 

 

 

GPS Antennas: Antennas are a huge factor in locating the exact position of equipment in the field. Without precise spatial reference, over application or under application of soil fertility products would be imminent. As farm equipment rolls and oscillates across a field, the GPS antenna mounted on the cab can convey inaccurate information of the exact position of the machine. This is due in part because these antennas receive satellite signals in a perpendicular relation to the ground. To compensate for pitch, yaw, and roll, gyroscopes are mounted within the antennas to determine the precise location. So even when a machine is on an incline where the antenna would be hanging over the ground, instead of directly over the machine, the center of the machine is located rather than the ground below the antenna.

 

Differential GPS (DGPS): This GPS system uses a reference base placed in a known location for spatial information as well as a GPS mounted directly on the machine which acts as a roving receiver. The reference base takes its known location and compares it with the coordinates received from satellites. The error is calculated between where the satellites says the base is located and the known location. The reference base then takes the same information and compensates for the same error relative to the roving receiver. This ultimately results in identifying a much more precise location of the machine in the field compared to regular antennas.

 

 

 

 

 

 

 

 

 

 

 

 

Yield Monitoring and Mapping: Many combines are equipped with sensors which record crop yields as it is being harvested. Using GPS and an onboard computer system, the amount of corn entering the grain storage tank is logged based on spatial location. With the resulting data, maps are created to visually represent the yield variability. With this information, it may be used in comparison with nutrient maps and remotely sensed imagery to view correlations between them. With the comparison, an answer can be found as to why areas of the field produced more grain than other areas.

 

Variable Rate Application: A network system that controls the rate of application of spray chemicals and fertilizer (dry, liquid, and gas). Utilizing a fertility prescription plan created by soil mapping, an on board computer allows for a regulated application based on geo-referenced data. The equipped GPS allows the system to determine its location in the field which informs the computer when to spread specific products. A drawback to this technology is that an individual may obtain more soil data than what a machine can apply at one time. Because each nutrient varies at a different level at separate locations, the sensors applying the product cannot handle the information overload. In turn, many nutrients may need to be applied at different times in order to get the desired precision application.

 

On-the-Go Vehicle-Based Soil Sensors: Devices are mounted to measure various properties of the soil and are commonly used with GPS to give maps of the field and even control the rate of application in real-time.

 

Soil Sampling: If a mounted sensor isn't applicable in a scenario, then by recording where samples are taken from by GPS and having the samples tested off-site at a different time it is still possible to create a map of the defining characteristics for studying.

 

Site-Specific Management of Soil pH: Since pH is a factor in determining lime application and what kinds of crops can be grown on certain parts of land it is commonly mapped for better coordination of farming practices in that area for more precision on the borders of the limits of what can be grown where.

 

Site-Specific Nitrogen Management for Irrigated Corn: There is a dead zone growing from the Mississippi River Delta in the Gulf of Mexico from the high content of nitrogen in the water that is directly related to the runoff of excess nitrogen used in farms that are a part of the Mississippi River Basin, this management works to reduce the excess nitrogen put into the land and thus reduces the amount going into the surface water nearby and everywhere downstream. 

 

Third Party Companies

• Trimble: 

• Raven: 

• Outback: