Review of SRI modifications in rice crop and water management and research issues for making further improvements in agricultural and water productivity

Much of the focus of agricultural improvement efforts in recent decades has been on modifying crops' genetic potential more than on improving cropping practices and production systems. Certainly, this genocentric approach has made significant contributions to food production in certain parts of the world under the banner of the Green Revolution. Yields have been raised substantially through varietal improvements and the increased use of inputs, including energy, agrochemicals, and delivering more water to crops through irrigation technology. In the past two decades, however, gains from this strategy have decelerated, with increasing economic and environmental costs of this input-dependent approach. Accordingly, there is reason to consider what can be accomplished by making optimizing changes in crops' growing environments both above ground and, especially, below ground. The System of Rice Intensification (SRI) developed in Madagascar has been showing that, by modifying crop, soil, water and nutrient management, it can under most of the circumstances evaluated thus far raise of the productivity of land, water, seeds, capital, and labor used for irrigated rice production. This article summarizes and reflects on the evidence provided in the preceding articles in this special issue. It draws on the scientific evaluations and field experience from Asia, Africa, and Latin America to offer some conclusions about the methodology known as SRI. Since this methodology is still evolving, no final assessment is possible. Much more research and evaluation remain to be done, and there will be further modifications and refinements since making adaptations to local conditions is regarded as intrinsic to the methodology. Further improvements in SRI will come from both researchers and farmers, with the latter considered as partners rather than simply adopters. This is consistent with SRI's representing a paradigm shift more than a fixed technology. The article identifies a number of areas for additional research that can probably improve factor productivity still further.