| Abstract: | Since upland rice under shifting cultivation is common, the mean paddy yield in sub-Sahara Africa (SSA), especially West Africa, has been stagnated at 1.3–1.7 t ha?1 during the past 30 years of 1970–2000. There exist numerous small inland valley swamps (IVS), of which 10 million ha is capable of being turned into small scale irrigated rice fields, i.e., sawah* by simple and low cost ecological engineering technology with farmer's self-support efforts. The fertility of lowland soils in West Africa was the lowest, particularly available phosphorous status was extremely poor and low pH as well as low exchangeable bases among the three tropics of Asia, Africa and Latin America. However, because of multi-functional mechanisms of soil and water conservation and replenishment of nutrients, sustainable productivity of 1 ha of lowland sawah system can be equivalent more than 10 ha of upland fields. Geological fertilization, nitrogen fixation, neutralization of pH and increase phosphorous availability are the important functions of the sawah system. Sustainable development of sawah systems in IVSs can contribute to increase food production and to restore the degraded watersheds of SSA. *Sawah: The term sawah refers to leveled rice field surrounded by bund with inlet and outlet connecting irrigation and drainage. The term originates from Malayo-Indonesian. The English term, Paddy or Paddi, also originates from the Malayo-Indonesian term, Padi, which means rice plant. The term, Paddy, refers to rice grain with husk in West Africa of SSA. Most of the paddy fields in the Asian countries correspond to the definition of the term sawah. Paddy field is almost equivalent to sawah for Asian scientists. However, the term paddy fields refers to just a rice field including upland rice field in West Africa of SSA. Therefore in order to avoid confusion between the terms rice plant, paddy, and the improved man-made rice growth environment through ecological engineering, the authors propose to use the term sawah. |
