- System of Rice Intensification
The System of Rice Intensification (SRI) is a method of increasing the yield of
riceproduced in farming. It was invented in 1983by the French JesuitFather Henri de Laulaniein Madagascar. However full testing of the system did not occur until some years later. The productivity of SRI is under debate between supporters and critics of the system.
History and main ideas of SRI
Assembly of the practices that culminated in SRI began in the 1960s based on Fr. de Laulanie's observation of 'positive-deviant' farmer practices, starting with planting single seedlings instead of multiple seedlings in a clump, and not keeping irrigated paddy fields flooded during the rice plants' vegetative growth stage. Planting with wider spacing in a square pattern, rather than randomly or in rows, followed, as did controlling weed growth by use of a soil-aerating push-weeder (rotating hoe).
In 1983, the beneficial effect of transplanting very young seedlings, less than 15 days old, was discovered serendipitously. Subsequently when fertilizer prices were raised, compost made from any decomposed biomass turned out to give even better results than chemical fertilizer. SRI concepts and practices continue to evolve as they are being adapted to rainfed (unirrigated) conditions and with transplanting being superseded by direct-seeding sometimes.
The synthesis of SRI has proceeded empirically, but the central principles for getting best results are:
* rice field soils should be kept moist rather than continuously saturated, minimizing anaerobic conditions, as this improves root growth and supports the growth and diversity of aerobic soil organisms;
* rice plants should be spaced optimally widely to permit more growth of roots and canopy and to keep all leaves photosynthetically active; and
* rice seedlings should be transplanted when young, less than 15 days old with just two leaves, quickly, shallow and carefully, to avoid trauma to roots and to minimize transplant shock.
These changes from conventional practice when managing plants, soil, water and nutrients induce more productive phenotypes from any rice genotype, although some varieties respond better than others to SRI methods. Increased yield is achieved with 80-90% reductions in seed requirements (lower plant population) and 25-50% less irrigation water. Chemical fertilizer and agrochemical crop protection can be used, but best results can be attained without use of purchased inputs.
pread of SRI
The spread of SRI from Madagascar to around the globe has been credited to
Norman Uphoff, director of the International Institute for Food, Agriculture and Developmentat Cornell University, Ithaca, New Yorkfrom 1990 to 2005. In 1993, Uphoff met officials from Association Tefy Saina, the non-governmental organisationset up in Madagascar in 1990by de Laulanie to promote SRI. After seeing the success of SRI for three years when Malagasy farmers previously averaging 2 tons/hectare averaged 8 tons/hectare with SRI, Uphoff became persuaded of the merits of the system, and in 1997started to promote SRI in Asia. As of 2007, the beneficial effects of SRI methods had been documented in 28 countries, most recently in Bhutan, Iraq, Iran and Zambia. Governments in the largest rice-producing countries (China, India and Indonesia) are now supporting SRI extension. In India, SRI concepts and practices have been extrapolated successfully to other crops such as sugar cane, finger milletand wheat.
There are criticisms of SRI. While
supportersof SRI report many benefits in addition to yield increase -- resistance to pests and diseases, resistance to abiotic stresses like drought and storm damage, more output of polished rice (in kg) when SRI paddy (unmilled rice) is processed (bushels), less chemical pollution of soil and water resources -- criticshave focused on yield suggesting that claims of increase are due to "poor record keeping and unscientific thinking" [http://www.nature.com/news/2004/040322/pf/428360a_pf.html] . Some critics have suggested that SRI success is unique to soil conditions in Madagascar, a point that is disputed by supporters.
Critics have objected that there is a lack of details on the methodology used in trials and a lack of publications in the peer-reviewed literature. This latter deficiency is now being remedied by such publications, but systematic trials that will satisfy scientific critics remain to be done. A global field trial is planned for 2009-2011, to be conducted by researchers from
Cornell University, Wageningen University, and the International Rice Research Institute [Norman T. Uphoff, "Food Revolution That Starts With Rice", New York Times, 17/6/2008, [http://www.nytimes.com/2008/06/17/science/17rice.html?pagewanted=1&8dpc] ]
Below is a picture gallery of SRI farming in
* [http://ciifad.cornell.edu/sri/ SRI] at
* [http://www.nature.com/news/2004/040322/pf/428360a_pf.html Article on SRI] from "Nature"
* [http://news.bbc.co.uk/1/hi/world/south_asia/4200688.stm News article on SRI] from the
Wikimedia Foundation. 2010.