Agriculture Reference
In-Depth Information
regulating or throttle valves (see Figure 10.2 for throttling valves). The ground speed
of the vehicle was determined by timing how long it took to drive a known distance.
While spraying, the operator tried to maintain a consistent, correct ground speed to
minimize the error in the application rate. Studies have shown that a great deal of
pesticide was applied at the wrong rate with these conventional sprayers (Rider and
Dickey, 1982; Grisso et al., 1988). The introduction of application rate controllers
in the latter 1970s was a major step in applying automation technology to improve
precision application and decrease chemical waste.
Because pesticides are potentially harmful products, accompanying their potential
for effective pest control are several significant negative by-products. First, widespread
and imprecise chemical application may cause adverse effects on the environment.
There are many environmental concerns that have been raised about the use of agri-
cultural chemicals. For example, chemicals can leach into the groundwater. Soil con-
tamination can occur if chemicals are overapplied. Damage to the environment can
then result from the inadvertent contact of nontarget organisms with pesticides through
both runoff and airborne drift. Grover et al. (1997), studying chemical application in
wheat crops, found that up to 36.6% of an inefficient application can drift out of the
target area, causing damage to nontarget organisms. Minimizing these environmental
impacts is an essential feature of pesticide application systems.
Another important concern should be addressed in the design of any pesticide
application system is the impact on the health and safety of the person who operates
the equipment that applies the pesticides onto the fields. Working with the chemicals
in a concentrated form can be dangerous to the applicator. There is potential for
spilling and exposure to the body. Application systems should minimize these kinds
of health and safety risks. Finally, any application technology should apply pesti-
cides accurately. Overapplication increases costs to the farmer and can damage the
crops and the environment. In most of the current agricultural production systems,
pest management constitutes a significant production cost, ranging from about 5% to
10% in typical row crops such as corn (Duffy, 2012) and from 30% to 40% in typi-
cal horticultural crops such as apples (Gallardo et al., 2010). Underapplication may
result in a failure of the pesticide to control the pest. This will result in lower profits
for the farmer because of reduced yields.
These issues have played a critical role in the advancement of the pesticide appli-
cation industry and the development of associated automation equipment over the
past several decades and will continue to do so. The goal of chemical application
has thus become twofold:
to control target pests while having a minimal impact on
nontarget subjects.
Much of the automation of chemical application equipment aims
to achieve this goal in both an efficient and cost-effective manner.
Equipment that improves the accuracy of pesticide application by ground-driven
sprayers has been investigated and is currently being manufactured by several com-
panies. As the first means of automating chemical application, electronic monitors
and rate controllers were developed to measure chemical application rates, display
these rates to the applicator, and provide a command signal to controllers. The com-
mand signal is then used to control the application rate as the ground speed of the
vehicle changes. Use of these electronic application rate monitors and controllers
reduce the application rate errors substantially (Grisso et al., 1988).
