Crop Yield Forecasting

esults are assigned to each sub-region to estimate the yield. However, this method does
not aim for an exact crop production forecast; rather, it is used as an expert assessment
of potential yield. The third method uses the amount of rainfall to generate a rainfall index.
The assumption is that each weather station has a weight proportional to the final crop
production. The equation for calculating this index is:
IPLUV = IP 1 x W 1 + (IP 2 – IP 1 ) x W 2 + (IP 3 – IP 2 ) x W 3 ,
where
IPLUV
Wj
Reference period
W1
W2
W3
= the rainfall index;
= the weight of each reference period considered in relation to its
contribution to agricultural production;
= 1 {September, October, November, December}; 2 {January,
February, March}; 3 {April, May};
= 0,35;
= 0.60; and
= 0.05.
The weights are estimated by means of a non-parametric method, maximizing the function
of correlation between the rainfall index and cereal production. The maximum correlation
value is approximately 0.93. Finally, the cereal production PCER is a function of the IPLUV:
PCER = ƒ0 (IPLUV).
3.2. Release calendars: punctuality and timeliness
The timeliness of the agricultural statistics 44 provided by the DSS is generally satisfactory,
although very general information is provided, such as the total cereal area and the production
at national level, and the statistics are released between July and September. The agricultural
statistics produced are published, but are not freely available. There is no predetermined
schedule for the publication of agricultural statistics. The quality of agricultural statistics is
neither reported nor documented, and little data analysis is performed. There is no procedure
for providing micro-data, and there is no single database that keeps track of the evolution
of all agricultural statistics or that stores primary data at farmer levels (Serghini 2012). Other
national sources, such as the HCP and the BAM, do not provide such information. Table 3.8
below illustrates the release frequency of yield forecasts and estimates, and acreage and
production estimates in Morocco, as well as the planting and harvesting calendars of the
main crops.
44
Agricultural season reports are available at: http://www.agriculture.gov.ma/rapports-statistiques
Crop Yield Forecasting: Methodological and Institutional Aspects 107