Agriculture Reference
In-Depth Information
The goal of this chapter is to examine a number of factors relating to the removal
of man as a control element in agricultural field production systems. Many forces
external to the industry will shape how automation evolves and is adopted by pro-
ducers. The objectives of this chapter are multifaceted: a review of historical trends
in field machinery, a look at the physical limitations the industry faces, brief treat-
ment of machine life and obsolescence, an extensive treatment of evolving automa-
tion technologies, discussion of automation technologies appropriate to specific field
practices, and speculation on trends we may see in the future.
5.2 HISTORICAL TRENDS IN FIELD MACHINERY
Before the development of U.S. agriculture, man learned to harness animal power.
Man as a power source only produced a mere 0.1 Hp (0.075 kW) over a sustained
period. However, by harnessing the power of oxen and draft horses, man found he
could be more productive, effectively multiplying his effort 6- to 7-fold per animal.
Along with the development of the external combustion engine came the ability to
achieve another 10-fold or more increase in productivity. With the ability to harness
animal and heat engine power sources, man was transitioning from a power source
to a control element, the overseer of how power was acquired and used to accomplish
field activities. Today, with modern agricultural tractors, man is in control of 450 kW
or more.
However, man as a control element is fallible. Furthermore, the increased use
of hired labor has separated and confused the control process. Whereas the farm
owners of the past were in the field to check on the quality and productivity of every
aspect of cultural practices, today, the decision-making process is being moved
from the field to the farm office, further complicating the feedback control process.
Because of other business-related responsibilities, farm managers are continually
forced to rely on hired labor to make decisions regarding the overall profitability of
increasingly larger operations. Furthermore, as profit margins shrink, farm operators
are forced to do more with less as they continue to substitute capital for labor. The
end result, the overall power and size of agricultural field machinery continues to
increase, and as this happens we note an increase in the magnitude of errors affect-
ing the bottom line. The simple mistakes of yesterday are now replicated over 100- to
1000-fold of the area covered just 50 years ago.
5.3
PHYSICAL LIMITATIONS OF FIELD MACHINERY
5.3.1 T
HE
P
OWER
D
ILEMMA
When looking at modern farm equipment, specifically equipment used to produce
grain crops, the trend has been to use higher power machines. For example, today
it is common to see 450-kW tractors on farms. To effectively utilize the power pro-
duced from the engine, the tractor must be adequately ballasted. In general, there
is a recommendation the tractor be ballasted at 60 to 70 kg/kW of engine power, or
from 27,000 to 31,500 kg total mass (Goering et al., 2003). Of course, when ballast-
ing a tractor it is not permissible to exceed tire manufacturer's recommendations for
