Management of rice production systems to increase productivity

The results will also be used to calibrate the Nitrogen Module of the
Nutrient Management Support Software (NuMaSS) for the Sahel region.
2.1.2. The Upland Production System
The Gambia is primarily an agricultural country on the southern
fringes of the semi‐arid Sahel region of West Africa. More than 75% of the
population depends on the agricultural and natural resource sectors for its
livelihood, but over the past two decades, production of cash and food crops
has steadily declined. This decline can directly be attributed to environmental
degradation. Dense forest and woodland covered 80% of the country during
the 1940s, but currently it accounts for less than 10% of the total land.
Uncontrolled burning is prevalent, fallow periods have been shortened or
eliminated, and deforestation for fuel wood is indiscriminate. An estimated
85% of the natural savannah woodland vegetation is burned each year for
agricultural and other purposes. Agriculture and burning contribute to
erosion, decline in soil fertility, prevalence of pests and disease, and
deforestation. Environmental degradation and decreased agricultural
production are serious issues in The Gambia, and conservation of natural
resources is a high priority for the government. Climatic changes since the
1970s have created further problems for the nationʹs agricultural base.
In The Gambia, it is estimated that there are probably 5,000 to 7,000 ha
that could be cultivated under upland rice. However, in 1995, it was
estimated that only 3,043 hectares were cultivated, with an average yield of 1.2
tons/ha (NASS 1995). Growth‐limiting factors such as limited water, low plant
17