Multi-functionality of Sawah Eco-Technology:

Role in Combating Soil Degradation and Pedological Implications

抄録

The low productivity of agricultural soils experienced in sub-Saharan Africa (SSA) has been attributed to the catastrophic soil degradation and inherent pedological factors of the region. Soil degradation in this region includes soil erosion by water and wind, extensive leaching due to extreme rainfall, salinity associated with aridity, spillage due to mining and associated problems of deforestation. In areas under traditional management techniques, the recent breakthroughs in biotechnology have not achieved many of the objectives of “Green Revolution”. The soils are highly weathered, low in essential plant nutrient and soil organic matter. The clay minerals in the majority of the soils are mainly oxides of aluminium and iron including non-expansive 1:1 minerals such as kaolinite. However, the region must aspire to achieve, at least in part, the goals of Millennium Development Goals. Sustainable rice production in SSA can be realized through a combination of biotechnology and improvement of the rice ecological environment through ecotechnology. The “sawah”, which is an Indonesian word meaning irrigated lowland is considered to be the missing concept for improving natural resources in the majority of African rice farmers’ fields. A sawah scheme is thus being fashioned to replicate the Japanese “satoyama”. This scheme presents one of the best options to the abundant inland valleys in SSA watersheds for the development of sustainable productivity and for efficient soil forming processes to continue without interruption. Under such schemes agricultural productivity is ensured, while the ecosystem remains stable with little or no degradation. Sawah ecotechnology can improve input efficiency, and when the sawah system has been integrated into improved agronomic practices, such as the system of rice intensification, paddy yields have increased from a low value of 2 t/ha through to 4 t/ha, and presently stands at nearly 10 t/ha. Moreover, sawah rice production has achieved stability of soil degradation, reducing regular soil erosion to within the soil loss tolerance limit that ensures sustainable production in SSA.