Environmental Engineering Reference
In-Depth Information
amount of labour used in herding and veterinary costs. This could, for
example, be represented as:
Q
l
5
A
a
L
l
b
(11.1)
Where:
Q
l
5 the amount of livestock produced (output in kg per year);
A
s
5 the area of land available for livestock production (hectares);
L
l
5 labour (person hours per year);
a, b
5 unknown parameter values to be estimated.
In this example, primary data would be required for the input and output
variables given in Equation 11.1. These data could be obtained through a
questionnaire survey of the local population answering the following type
of questions:
Livestock production data:
1.
Do you keep livestock?
2.
What type of livestock do you rear: sheep, cattle, goats, poultry?
3.
What was the calving/lambing, and so on, rate of this livestock in the
past year?
4.
What was the mortality rate of your livestock in the past year?
5.
What are the uses of your livestock other than for meat production,
for example, milk, manure?
6.
How much of each of these products was produced?
7.
How many people were involved in caring for your livestock and for
how many hours did each work?
It should be noted that this illustration gives an example of the kinds of
questions that should be asked in a questionnaire survey but not of the
form the questions should take. To elucidate the correct information,
questionnaire surveys must be presented in an objective manner and in a
way that can be understood by the recipients of the questionnaire.
A simplii ed example of the results of such a study is given in Table
11.1 using only two inputs, labour and land area, and three study areas.
To make a comparison over time, two dif erent approaches can be taken:
either the survey can be longitudinal, that is, carried out over a number of
years, or cross-sectional, that is, carried out at the same time but over a
number of dif erent study sites. This will then provide variation in the data
of the inputs into production.
