SSCD Concept and Complexities

Simple concept:

Use the concept of an irrigation system—one main pipe close to the orchard floor with sprinklers (or emitters) evenly spaced to apply water, fertilizers and herbicides.  Twist: install similar systems higher in the canopy and attached to existing trellis wire to apply water, pesticides, and nutrients that will cover the canopy.

The complexities:

Orchard piping hydraulics: The uniformity and precision of chemical application via an irrigation system is heavily dependent on piping hydraulics, and an appropriate control of the flow within the piping network is key to achieving uniform and precise chemical delivery.  Minimizing pipe sizes and runs, branch points and laterals are important points to consider and require careful analysis of hydraulic flows.

Chemical injection and mixing system: Controls are needed to inject precise amounts of various chemicals into the SSCD system utilizing existing irrigation input sources.  Additionally, a system must uniformly mix injected chemicals in the water stream to ensure an even application from first to last nozzle.

Emitter orientation, spray patterns/deposition, canopy distribution and coverage: Deposition characteristics and uniformity of spray material concentrations from emitter to emitter and with changes in dose level must be investigated and optimized. Inert sprayable dyes will be used for analysis of crop canopy penetration and distribution as well as non-target deposition.

System residue management and re-capture of spray materials:  Chemical residue within the piping system could be controlled at an acceptable level if we could remove all the water diluted spray materials from the piping system.  Pressure-compensating valves and leak-prevention nozzles will be installed in-line to delay and synchronize emission of sprays at a target pressure after the lines have been fully charged, as well as to provide a means of clearing the lines with water or compressed air during a purge phase after spray delivery. Flushing system hydraulics will be studied to minimize spray materials loss and potential point-source contaminants, as well as strategies for mitigation of potential clogging issues

Direct injection vs. common tank pre-mixes: While common tank pre-mixes may be most efficient for smaller plots, direct injection has a number of advantages (Landers, 1992, 1997), such as no tank washing or point source pollution, potential automation and closed transfer connection of pesticides, an ability to change dose rate easily, and ability to inject multiple products, etc.  Both systems need to be examined in a new SSCD system.

References:
1. Landers, A.J. (1992). An evaluation of the Dose 2000 direct injection crop sprayer. Proc. of Ag Eng ’92 International Conference on Agricultural Engineering, Uppsala.
p.336. Uppsala: Swedish Institute of Agricultural Engineering.
2. Landers, A.J. (1997). A compressed air direct injection crop sprayer. Optimizing
pesticide applications. Aspects of Applied Biology, 48. Pp. 25-32. Wellesbourne:
Association of Applied Biologists.

04.04.12

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