Soil quality in rice-based rainfed lowlands of Asia: characterization and distribution

Abstract

The rainfed lowland rice production system in Asia covers about 46 million hectares, which is almost 30% of the total rice area worldwide. Production in much of this system is hampered by drought, submergence, and multiple soil constraints. The Green Revolution largely bypassed these difficult environments and they continue to be characterized by low agricultural productivity and widespread poverty. More recently, there has been some success with technology development and adaptation. However, the potential and realized benefits from research and development efforts in the rainfed lowland ecosystem will continue to strongly depend on indigenous soil fertility and soil-related constraints. As a first step in our effort to better characterize soil and water resources in rice-based rainfed lowland systems at the regional and landscape level, we characterized the distribution and frequency of soil constraints in rainfed lowlands. Seven percent of rainfed rice is grown on problem soils such as acid-sulfate soils or saline soils. One-third of rainfed lowland rice is grown on relatively fertile soils, slightly less than one-third grows on soils with low indigenous soil fertility, and slightly more than one-third grows on soils with considerable soil constraints often combined with very low soil fertility. Rainfed lowland rice in Southeast Asia is much more likely to be on poor soils with various soil constraints than in South and East/Northeast Asia.