Management of rice production systems to increase productivity

Figure 4. Map of Republic of The Gambia, West Africa, Showing
Upland Rice Trial site location
The rainy season typically extends from late May to early October;
however, both ends of the rainy season have shortened in recent years.
Average annual rainfall for the country in 1999 was 1,083 mm. The 10‐year
normal average in 2000 was 804.3 mm in the western half of the country, and
700.3 mm in the eastern half. Average annual minimum temperatures in this
tropical country is 21C°, with a maximum mean of 33C°.
2.2.2. Field Experiment Design
The field experiments were conducted during the rainy season of 2000,
2001 and 2002 at the Gambia National Agricultural Research Institute’s
experimental fields in Brikama, Western Gambia.
The experimental design was split‐plot, with fertilizer level as the main
plot, and variety as sub‐plot. Four fertility levels and four varieties were
studied. The main plots were not replicated. Each variety was replicated 3
times in each main plot. The test varieties were the best entries from a
previous 3‐year low‐input varietal screening exercise of 10 new low‐input
varieties from WARDA. Peking being the most widely grown upland rice
variety in The Gambia was selected as the local check. It is a short‐stature
variety maturing within 80 to 85 days. There were a total of 48 sub‐plots in
the trial (see Appendix 1). The treatment levels were as follows:
Main plots: Fertilizer application rates
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