Appendix I - Example of Methodology Used in the Estimation of Pesticide Use at the Provincial and County Levels
For All Crops in the Survey
The expansion factor for each crop is the ratio of the total area of each crop to the area of that crop (sprayed or not) reported in the survey.
Example: Calculation of expansion factor for soybeans
Total area of soybeans in 2008: 2,100,000 acres
Total area of soybeans reported in survey: 94,780 acres
Therefore, the expansion factor for soybeans is: 2,100,000 / 94,780 = 22.16
For each record in the sample, the quantity of active ingredient of all chemicals was computed by multiplying area sprayed times concentration times application rate. The sample total for each pesticide used was then multiplied by the expansion factor for the corresponding treated crop to arrive at an estimate of the total quantity of active ingredient for a particular pesticide used.
Example: Estimation of s-metolachlor used on soybeans in the province
Total quantity of active ingredient of s-metolachlor used on soybeans in the sample was 3,734.64 kg.
Therefore, the total quantity of active ingredient of s-metolachlor used on soybeans would be:
3,734.64 x 22.16 = 82,760 kg
(This is the figure that appears in Appendix II.)
Once the provincial level estimate of pesticide usage was determined, the total was allocated to counties on the basis of area grown.
Example: Estimation of s-metolachlor used on soybeans in Lambton County
The area grown to soybeans in Lambton County (243,000 acres in 2008) accounted for 11.6% of the provincial total.
Therefore, the total quantity of active ingredient of s-metolachlor used on soybeans in Lambton County would be:
0.116 x 82,760 = 9,600 kg
(This represents the share that s-metolachlor use on soybeans contributes to the Lambton County estimate for "other herbicides", which appears in Appendix VIII.)
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