improved fallow systems in the luang prabang area, lao pdr - Afaci

Improved fallow systems in the Luang Prabang area, Lao PDR – an analysis based on farmer experiencesDiscussionDiscussionSources of errorsThe reliability of the results presented above can be questioned from a statistical point 3f view. Inorder to compare yields, for instance, under the same conditions, very few points of data could beused. Mainly, mean values were used for comparisons, but the actual data ranges can givesecond thoughts about their accuracy. Examples of this are given in Figures 12 and 13, where95% confidence intervals for the means are shown.Figure 12: Same as figure 6, but presented asbars with confidence interval.Figure 13: Same as figure 7, presented as barswith confidence interval.Figure 12 reveals large and overlapping confidence intervals for the mean yields in thecomparison between normal and improved fallow (the last confidence bar is not missing –there isonly one data point). Of course, this is a serious threat to the reliance of the presented result. Onthe other hand, the diagrams can be seen as a visualisation of a theoretical relationship that issupported by the farmers views.Figure 13 shows that the mean yields over the three parts of the plot are almost the same. withoverlapping confidence intervals. This makes conclusions drawn from average figures highlyuncertain. The data variances could be due to mistakes in the crop cuts: the 2x2-m. squaresmight have been marked incorrectly and harvesting could have been careless. Anotherinterpretation is that the plot actually showed very varying yields over- and within the parts This issupported by the author's impression from the field.The interviews are almost the only source of information and data may, as shown above, haveerrors. It may be hard to remember correctly how much rice was planted and harvested ten yearsago. Another problem is that the conversion from kalong is based on mean figures that may differfrom the real relations at the plot. This means that areas, production and yields all have someerrors, but must be accepted as the farmer's memory is the only way to vet this information.Interpretation of the resultsToo much work?A main problem may be that most farmers say there was additional work in introducing theimproved fallow species. As labour availability at sowing is often critical, additional support fromthe project might be needed. This is a threat to the spreading of the methods to other farmers andplots in the village. After implementation there seems to be little extra work for the farmers,except where grasses have been introduced.Another problem might be the availability of seeds from the legumes in the quantities needed, butthis was not specifically expressed.IMPROVED FALLOW SYSTEMS IN THE LUANG PRABANG AREA, LAO PDR - AN ANALYSIS BASED ON FARMEREXPERIENCES.20040940 12