This is mainly related to the complex technical issues required, poor extension service, lack of capital or more simply poverty (Mati B.M. et al., 2011). As a consequence of population growth and urbanization during the second half of the twentieth century, rice demand has greatly increased. Thus rice is becoming a major staple crop in much of sub-Saharan Africa (W.A Stoop et al., 2002).
The System of Rice Intensification (SRI) was synthesized in 1983 by a French Jesuit priest, Father Henry de Laulaníe, in Madagascar after an attentive and critical observation of the local traditional rice system during the previous two decades.
Although each components was already practiced, this method can be considered a real innovation because for the first time it resumes all of them in a unique package. The main benefit is an increasing yield achieved by using less water, employing local varieties, anticipating single plants transplanting, soil aeration and wider spacing between plants. Concerning inputs it doesn’t employ neither fertilizers nor pesticides.
The system of rice intensification (SRI) represents an integrated and agro-ecologically responsive, interdisciplinary approach to rice cultivation (A. Dobermann 2004). It’s an integrated crop management approach characterized as ‘knowledge intensive’, a process that involves a wide range of agronomic practices that together result in synergistic effects. More than a technology to be applied in a standardized way, it is a set of principles enhancing plant growth performance and productivity that can be adapted to the very diverse agro-ecological environments of rice production.
The major elements of the SRI (Laulaníe, 1993a,b) strategy are:
- raising seedlings in a carefully managed nursery
- early transplanting of 8 to 15 days old seedlings
- single widely spaced transplants
- early and regular weeding
- carefully controlled water management
- application of compost to the extent possible
Young seedlings must be handled very carefully when transplanting, keeping roots moist. Square pattern with a wide spacing (25x25 cm) of single seedlings facilitates mechanized weeding that ensures soil aeration and reduces intra-specific competition. Weeds need to be controlled regularly, starting about 10 days after transplanting. Water management is a crucial part of this system: it must be ensured that soil is well drained and in moist aerated conditions that facilitate roots’ development and depth and the release of organic P from soil microbial biomass. Rice is grown under intermitted irrigation making possible considerable water savings (up to 50% less than conventional technique) with the unflooded phase during the vegetative growth stage. Water management also affects the mineralization’s rate of organic sources, the only nutrient input of the SRI: in aerobic conditions the BNF (biological Nitrogen Fixation) and the performance of microorganisms are more efficient thus increasing the readily available nutrient supply, including a wide range of micronutrients. The increased yields registered during experimentations all over the world are achieved not by higher levels of external inputs but rather through more productive use of natural resources (land, water, seeds and plant nutrients), and of labour, time and space. This can contribute toward realizing a future agriculture that is more sustainable and in great harmony with nature than is presently the case (Bonte-Friedheim et al., 1994).
- Bonte-Friedheim et al., 1994 Challenges to the biophysical and human resource base. In: Fresco, L.O., Stroosnijder, L., Bouma, J., van Keulen, H. (Eds), The Future of the Land: Mobilizing and Integrating Knowledge for Land Use Options. Poceedings of the 75th Anniversary Conference of the Wageningen University, 22-25 August 1993. John Wiley, London, UK, pp. 65-79.
- Dobermann A., 2004 A critical assessment of the system of rice intensification (SRI) Agricultural Systems 79 (2004) 261-281
- Mati B.M., 2011 Introduction of the system of Rice Intensification in Kenya: experiences from Mwea Irrigation Scheme. Paddy Water Environ (2011) 9:145-154
- Laulaníe H., 1993a. Le système de riziculture intensive malgache. Tropicultura (Brussels) 11, 110-114.
- Laulaníe H., 1993b. Technical presentation on the System of Rice Intensification, based on Katayama’s tillering model. Unpublished paper, translated from French, available from Cornell International Institute for Food, Agriculture and Development, Ithaca, NY.
- Stoop W.A. et al., 2002 A review of agricultural research issues raised by the system of rice intensification (SRI) from Madagascar: opportunities for improving farming systems for resource-poor farmers. Agricultural Systems 71 (2002) 249-274