System of Rice Intensification

In general, the term System of Rice Intensification (SRI) characterizes a management system for irrigated rice production in which very young rice seedlings are planted singly in a square grid pattern. The soil is kept moist but well-drained for the entire growing period. Since flooding of the rice field is not part of this management practice, weeding has to be done either by hand or mechanically. Organic fertilizers should be preferred over inorganic ones. There is no common strict guideline which defines an SRI system. It can rather be seen as a science-based collection of management options. Farmers can choose the most suitable technologies and adapt them according to their local conditions. SRI reduces costs for irrigation water, seeds, and fertilizers, which leads to more income for farmers. 

The traditional practice of continuous flooding of the rice field produces a significant amount of greenhouse gas (GHG), specifically methane (CH4). With SRI, soil moisture is kept at an optimum level, thus, reducing methane emission from rice production. Opting for organic fertilizers over the synthetic nitrogen fertilizers, which emit the GHG nitrous oxide (N2O), also reduces the GHG contribution from rice production.

Further reading

IRRI Photo