The surveys were conducted by personal visits to the farmers in the
daytime by two interviewers. The interview was face-to-face,
participation was entirely voluntary, and farmers were free to deny
information without further justification. In practice, no farmer
objected and all questionnaires included in the final dataset were
complete for the pesticide use data. To protect the rights, dignity,
safety, and well-being of the respondents, ethical clearance was sought
and issued by the Commission for Ethic of Health study from Dustira
Hospital Cimahi, West Java. Each participant received a gift of staple
food as compensation, such as instant noodles, coffee/tea, cooking oil,
and sugar. The questionnaire forms were filled in by the interviewers.
During the survey, interviewers did not only record the respondent
answers but also performed a crosschecking to confirm his or her
response to avoid misunderstanding, especially regarding the pesticide
application practice. For example, farmers were asked to show the
interviewer the materials and equipment they used or to demonstrate
their pesticide application practices in order to avoid confusion.
Interviewers checked the weight percentage or concentration of pesticide
from each product, amount of application, and the brand package was also
photographed for further reference. Whenever farmers used a container or
spraying tank in their pesticide preparation, the container’s or tank’s
dimensions or volume were measured.
2.3 Estimation of Pesticide
Usage
Equation 1 was applied to calculate the pesticide use (i.e.,
expressed in active ingredient or a.i.) per year. Throughout the paper,
the words pesticide and active ingredient are used as synonyms. We use
the term “pesticide brand” to refer to a product of pesticides sold as
a specific formulation.
\(Pa=\frac{C\ \times\ V\ \times\ f}{A}\) (1)
Where, Pa is the annual amount of pesticide usage per hectare (g
/ha/year), C is the concentration of the active ingredient in the
product (g/l), V is the total spraying volume of pesticide brand
(l/application), f is frequency of pesticide application
(times/year), and A is the size of surveyed agricultural area of
each individual farmer (ha).
In case the applied pesticide was in solid form, its concentration was
expressed as a weight percentage (Equation 2 ).
\(Pa=\frac{\%w\ \times\ W\ \times f\ }{A}\) (2)
With the following new parameters, i.e. %w is weight percentage
of a.i. in the pesticide brand (%) and W is the total weight of
the pesticide brand used (g/application).
2.4 Comparing Prescribed vs. Actual
Use
For rice, which covered almost 65% of the surveyed area, the prescribed
use of pesticide was compared to the actual use. The data on the
prescribed use was mostly taken from the Indonesian national guidelines
(Directorate of fertilizers and pesticides, 2019). This was done per
brand, since prescription instructions are brand-specific. When
information on the minimum and maximum prescribed use per hectare were
available, these were compared with the actual use. When only prescribed
dilution ranges were available, these values were also compared with the
actual dilution value from the survey result. In case the brand was not
recommended for use on rice, we used the minimum and maximum prescribed
use values from other crops.