Agriculture Reference
In-Depth Information
In the past two decades, the widespread availability of microprocessors, along
with appropriate sensors and actuators, has made it possible to design and manufac-
ture sprayer control systems that are reliable and increase the application accuracy of
chemicals. Various application technologies for selective and variable rate applica-
tion (VRA) have been designed and evaluated in the past. Some selective application
systems have also been commercialized. There, however, still exist several critical
challenges for the wider adoption of such application systems: (1) variability of the
crop type and canopy systems, (2) complexity of the machine, (3) lack of scientific
knowledge connecting application rate to biological efficacy, and (4) questions about
return on initial investment. It is expected that the future development of applica-
tion automation technologies will address these issues to bring the technologies into
wider adoption.
The remainder of this chapter will focus on the requirements, evolution, and
future of chemical application system automation (use of the term “chemical” within
this chapter refers to pesticide, if not mentioned otherwise, that is, fertilizer system
automation is not specifically addressed in this chapter). Section 10.2 will discuss the
fundamental principles and requirements of chemical application systems. Various
types of controllers used in the automation of pesticide application systems are dis-
cussed in Section 10.3. Section 10.4 will present some of the recent advancements
in pesticide application technologies and systems with a particular focus on VRA.
Finally, in Section 10.5, the future directions of pesticide application automation
technology will be discussed.
10.2 FUNDAMENTAL REQUIREMENTS FOR
CHEMICAL APPLICATION SYSTEMS
The biophysical requirements for applying a chemical for pest control drive equip-
ment design and application techniques present in the agricultural industry. A con-
tinually improved understanding of these requirements is a significant driving force
behind the development of many automation technologies. The delivery of liquid
chemicals for pest control will have different requirements for various types of crops,
such as row and field crops and specialty crops (e.g., tree fruits, nuts, berries, and
vegetables). In addition, chemical application will be dependent on the type of pest
(e.g., weeds, insects, or fungi) to be controlled and the specific species of crop and
pest. There is considerable knowledge and experience that should be obtained by the
applicator through training and product labels. However, there are some important
performance requirements common to different chemical application systems such
as accurate application rate, uniform deposition, minimal off-target movement, and
minimal risk to health and safety of operators. In this section, these general require-
ments of a chemical application system will be considered.
10.2.1 C
ORRECT
A
PPLICATION
R
ATE
First, application equipment must apply the correct application rate consistently to
the crop or field area. The formulation application rate for a particular chemical is
specified in volume or mass units of chemical formulation, that is, the purchased
