Our crop yield forecasting
system has been validated with reported yields from Zambia and Zimbabwe both at provincial
and at communal level. Figures 1-4 present scatterplots of provincial reported
versus predicted yields for the years 1994 to 1997. Correlation coefficients(R2)
typically vary between 0.7 and 0.85. The scatter in the data is due to
inaccuracies in both the satellite derived and reported ground data. Figure 5
shows a typical example of the development of the correlation coefficient between the
reported
maize yield and the predicted maize yield as a function of the time of the
forecast. The figure clearly shows that the correlation coefficient and the
error of estimate stabilize halfway the growing season. Therefore, a
reliable crop yield forecast can already be provided halfway the growing season.
Figure 1 -4
Figure 5
