QUALITATIVE
MODELS OF THE FARM SYSTEM
CIRCULAR
DIAGRAM METHOD
An
easily comprehended representation of the inputs and outputs of the
farm system, most useful at this level of analysis, is the circular
diagram method. It shows the relationship between the various factors
determining the output and also as a way of defining subsystems
within the systems because of the complexity of the whole system.
STEP1
The
first step is to put in the centre of the diagram, the output of
central interest. The major factors which are thought to influence
this output are grouped in a ring about the centre with arrows
pointing inwards. The diagram also shows the effects of these factors
on each other in the same ring by arrows travelling around the circle
- see diagram 3-4. All of the inner ring factors can in turn, be
controlled or influenced if enough is known about them.
STEP2
- SECONDARY FACTORS
Those
factors which influence the inner ring are shown in a second outer
ring. However, the analyst should avoid excessive complexity and
include only those factors which are major determinants of the
central output. There can be further rings showing the expansion of
the analysis aimed at achieving greater understanding and improved
capacity of a successful operation.
STEP
3 – THE SUBSYSTEM
The
subsystem is concerned with the effects on the central output of
changes in one component of the system. The subsystem consists of the
centre, a component in one of the rings and all the factors that link
the two. Even the process of developing the diagram is useful as it
helps to clarify and understand the farm system. Underlines that the
system consists of subsystems and that it itself is part of a bigger
system. For example, the Australian farm model is directly subject to
a number of international environments.
MONITORING
PERFORMANCE
There
are a number of ways to monitor farm performance. For example, the
use of physical performance, yields, or gross margins. Monitoring can
also be classified according to the position of the criteria used in
the farm system. For example the use of central outputs such as
yields and profits or key determinants such as the soil's organic
matter, nitrogen and phosphorous levels, soil moisture. The other
method is the use of "indices of efficiency" including
"output/input" ratios.
LIMITING
FACTORS
Crop
and animal production rates are governed by the availability of many
growth factors such as minerals in the soil and climate. Process
rates are determined by the level of the most limiting factor which
when overcome raises the level of production to the next limiting
factor. If it were possible to overcome all the limitations, the
yield potential would be obtained.