Environmental Engineering Reference
In-Depth Information
Table 11.2
Hypothetical results from agricultural questionnaire survey
Input into Crop
Production
Amount of Input
Used Per Year
Amount of Crop
Output (kg)
Rainfall (mm)
1000
898
Labour (hours)
1500
Area (ha)
20
Rainfall (mm)
500
503
Labour (hours)
800
Area (ha)
20
Rainfall (mm)
100
467
Labour (hours)
1000
Area (ha)
50
Step 2: Calculating the value of the ecosystem in terms of water produc-
tion Once the production function has been identii ed, the value of the
ecosystem can be calculated by estimating the value of the agricultural
products. Data are therefore required on the price of agricultural prod-
ucts, and on the costs of production. Again these data would be collected
through a questionnaire survey, either of the householders involved in pro-
duction or through other individuals who have knowledge of the markets.
Crop costs data:
1.
What was the price of the crops that were sold?
2.
How much of the crops were retained for home consumption?
3.
What was the price of labour and other inputs into production, for
example, fertilizer?
With this information, a proi t function can be written:
P 5 P C Q 2 C
(11.15)
Where:
P 5 total proi t ($);
P C 5 price of crop ($/kg);
Q 5 quantity of crop produced (kg);
C 5 costs of production of crop ($).
Substituting Equation 11.14 into Equation 11.15 gives:
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