Agriculture Reference
In-Depth Information
gardeners on the site. The remaining people represented the other actors
of the agri-ecosystem. Before the survey, the team received a short
training session in various aspects of the project such as the questionnaire,
concepts of agriculture, investigative techniques and the psychological
aspects of the investigation. An initial site visit was undertaken to see how the
Centre Agricole de N'djili was structured and to identify the actors involved
in UA.
The investigation of the Centre Agricole de N'djili market gardeners was
conducted with a probability survey in sampling and a focus group. Each
interviewee was asked identical questions and received the same explanations,
allowing the information to be collected in a consistent manner in the farmer
survey.
Questionnaire for market gardeners
A questionnaire was designed containing 109 questions regarding the structure
of market gardeners and the organization of UA. Before the final questions
were selected, a field investigation was conducted on 14 market gardeners,
chosen at random, to collect relevant information and to test their semantic
comprehension of typical questions. Their replies were used to improve the
final questionnaire, which was then reviewed by psychologist academic
advisors. The questionnaire was written in French but administered in the
local language, Lingala.
Sampling area, sample size and parameters
The survey site was determined after collaboration with the management
committee of the Centre Agricole de N'djili. The sampling area consisted of
594 market gardening plots. The plot was chosen as the unit of sampling and
analysis for the survey, and each plot was assigned an identification number.
Market gardeners in the sample area are distributed in four groupings: blocks
A, B, C and D. The sample size (N) was fixed at 303 plots corresponding to
303 market gardeners. The parameters
identified for
inclusion in the
questionnaire are given opposite.
Testing irrigation water
Choice of sampling sites and sample collections
Ten sampling sites (see Table 8.1) were chosen on the basis of geographical
location.
Samples of water for chemical analyses were collected according to the
protocol described in the literature (Rodier, 1984). For each site, one sample
was collected, usually during the second week of the month, for 12 months.
Samples for bacteriological analyses were collected from the seven most
frequented sites (ENDA, EPP, EET, ERO, EPA, EMA and EPNA). Water
samples were collected in borosilicate glass bottles that had been washed and
rinsed with distilled water and then sterilized in an autoclave at 1208Ctoa
pressure of 150 kg/cm
2
for 30minutes. In most cases, samples were collected
