SRI as a methodology for raising crop and water productivity: productive adaptations in rice agronomy and irrigation water management

The System of Rice Intensification (SRI), developed in Madagascar almost 30 years ago, modifies certain practices for managing plants, soil, water, and nutrients with the effect of raising the productivity of the land, labor, and capital devoted to rice production. Certain production inputs are reduced-seeds, inorganic fertilizer, water, and fuel where water is pumped-with increased yield as a result. This paper introduces the subject of SRI, which is then addressed variously in the articles that follow. SRI is gaining interest and application in over 40 countries around the world. Its practices make soil conditions more aerobic and promote greater root growth, as well as larger, more diverse communities of beneficial soil biota. These below-ground changes support more productive phenotypes above-ground for practically all rice genotypes (cultivars) tested so far, with supportive evidence accumulating both from scientific institutions and field applications. SRI methodology remains controversial in some circles, however, because of the transformational change it introductions into traditional lowland rice production systems. This issue of PAWE brings together the results of formal research on SRI in a number of countries (Part I) and also reports on initiatives by government agencies, NGOs, universities, or the private sector, bringing knowledge of SRI to farmers in a wide range of agroecological circumstances (Part II). This introduction presents the basic principles that underlie SRI and discusses the nature of this innovation as well as considers some of the issues in contention. SRI continues to evolve and expand, being a work in progress. Its concepts and methods are being extended also to upland (rainfed) rice production, as well to other crops. Accordingly, SRI should not be regarded or evaluated in conventional terms as if it were a typical component technology. It is understood more appropriately in terms of a paradigm shift for rice production. In particular, it calls into question the long-standing belief that rice is best produced under continuously flooded conditions.