Precision Farming Profitability Reference E: Variable-Rate Technologies By Case Medlin, Stephen Hawkins, Keith Morris, Sam Parsons

Figure 5. Several equipment additions are needed for most VRT applications while some equipment additions may be optional. Precision Farming Profitability, p. 89

Figure 4. Most of the VRT equipment can be transferred between different applicators. For example, a global positioning system used during a pesticide application may also be used during the fertilizer application. Precision Farming Profitability, p. 90

Figure 1. Site-specific herbicide applicators often carry only water in their bulk tank, such as the 1000 gallon tank on this sprayer. The concentrated herbicide is then pumped into a mixing manifold where it is diluted with the water to achieve the proper rate before entering the spray boom. (photo provided by Aventis CropSciences) Mixing Manifold Precision Farming Profitability, p. 90

Figure 4. Some commercially available applicators are equipped with multiple nozzle systems. Generally, the nozzle selection is based on flow rate. This applicator is capable of changing flow from 5 to 10 to 15 gallons per acre while moving through the field. (photo provided by Aventis CropSciences) 3 Nozzles Precision Farming Profitability, p. 91

Figure 5. AIM Navigation System: a) in the cab of a SPX 4260 sprayer; and b) in the cab of a Titan floater: (photos provided by CNH Precision Farming Global Product Line) Precision Farming Profitability, p. 92

Figure 6. Some recently developed weed sensors are capable of detecting green plant material, then as the weed passes under the nozzle, an electronically controlled solenoid valve opens, to spray the weed. The down-side of these systems is the inability to distinguish between crops and weeds. (photo provided by Dr. Tom Jordan, Purdue University) Electronic Solenoid Sensor Precision Farming Profitability, p. 92

Figure 7. VRT applications are controlled by hydraulic motors on this spinner spreader which vary the rate based on the field location. Traditionally the rate would have been controlled by the flow gate and a ground-drive to the conveyor chain. Precision Farming Profitability, p. 93

Figure 8. The hydraulically driven system is not complete without a ground- speed sensor since rate is still dependent on area covered in a specified time. Precision Farming Profitability, p. 93

Figure 9. Prescription maps of soil amendments can be uploaded into an onboard computer for application. As the applicator moves across the field, flow-rate controllers adjust the rate as needed. (map provided by Michael Cox, Mississippi State University) Precision Farming Profitability, p. 94

Figure10. Often VRT decisions are made based on (a) soil survey maps or (b) topographical maps. Although similar in some cases, these properties may not convey the major variability in any given field. Careful consideration should be given to the source of information, it’s resolution, and other factors in the field influencing the parameter: (maps provided by Robert Nielsen) Precision Farming Profitability, p. 94

Figure 11. The Purdue University Multipurpose Imaging System (PUMIS) (a) is equipped with a tunable filter (b) to allow the simultaneous capture of reflectance from four predetermined wavelengths ranging from 500 nm to 1000nm. Although this system is currently in the developmental stage, one day it may be used to differentiate among weed species and the crop ©. Then the appropriate herbicide could be applied for each weed infestation. (photos provided by John Brost, Nic Radford, Leonard Lobo, Gaines Miles, and Okan ersoy) PUMIS Sensor 150 watt bulbs provides consistent lighting in daytime and offer potential for nighttime spraying Filter Housing for 4 filters Classification Process Brown = ground Green = corn crop Red = weed Precision Farming Profitability, p. 95

Figure 12. Dry fertilizer spinner spreaders can be calibrated more accurately in the field. Calibrating this equipment on-the-go allows checking of application rate per acre as well as rate across the swath. Precision Farming Profitability, p. 96