The System of Rice Intensification – known as SRI – is a set of agricultural methods for optimising resources developed in the 1980’s in Madagascar. SRI aims to increase the rice farming yields while reducing inputs such as water, seeds and fertilisers, so that rice farming becomes more profitable to the farmers. Unlike the techniques inherited from the Green Revolution, SRI does not depend on genetics engineering and chemicals. Depending on the countries and conditions, SRI can improve the yields from 20% to 100% compared to conventional farming.
SRI involves significantly reducing the number of rice seeds planted, transplanting them to the fields when they are much younger than usual, using different amounts of water at critical times of their growth cycle, and improving soil conditions with organic manure. […]
In Tamil Nadu, farmers are experiencing similar increases and are paying less. “Our chief minister’s aim is to get double the yield and triple the income of farmers using SRI. Traditional farmers use 30kg of seeds [compared with] 3kg by the SRI method” The Guardian
Transplantation: In SRI, young seedlings are planted individually, instead of transplanting several mature seedlings. Thus, the seed requirements are 90% lower than in traditional rice farming. The seedlings are planted in a matrix pattern (25x25cm) with a wide spacing between the rows to allow for an increased exposure to the sun and wind, as well as better access to soil nutrients. The roots have to be intact and the seedling is planted shallowly (1-2cm instead of 3-4cm).
With SRI, optimum spacing can be up to 50 x 50 cm (4 plants per sq.m) for very fertile soils. Best spacing is a function of soil fertility. Source: SRI Issue 6, 2009
Water management: In SRI, the fields are not permanently flooded, reducing the water consumption of the fields by up to 50% and decreasing methane emissions by oxygenating the soil. The cracks in the soil occurring when the fields dry allow for better oxygenation of the soil promoting root growth. When the fields are not permanently flooded, the plants also grow stronger stalks, which makes them more productive and resilient to bad weather conditions.
Weeding: SRI calls for regular weeding with rotary tools, which also aerates the soil.
Fertilisers: In SRI, the use of synthetic fertilisers and pesticides is reduced or banished while promoting the use of organic fertilisers such as green manure and compost. The nutrients are obtained by micro-organisms.
SRI is not a standardised technological method, it is adapted from country to country and adapted to local conditions. It has lead to larger yields with lower inputs in many farms, although in other places it has been abandoned as not more efficient than traditional methods.
Adoption: As with any new technology and radically different approach to farming, farmers have to change their habitual way of farming for SRI, which makes it difficult to adopt.
Labour: In the beginning, SRI might require more labour for transplanting and weeding. Once the farmers are experienced in SRI patterns it does not require more labour, some farmers report requiring less labour.
Automation: The existing machines for rice transplanting are made for transplanting several seedlings at once, in a narrow matrix.
If a machine adapted to SRI can be built, the adoption would be easier as it will decrease labour requirements.
SRI history in Tamil Nadu
The Department of Agriculture of the Government has included SRI in all existing and new schemes funded by Governement of India that focus on increasing food production. […]
Further trials conducted at Aduthurai and Thanjavur showed that adopting all SRI components resulted in 48.8 per cent higher yield at Aduthurai and 35.8 per cent higher yield at Thanjavur when compared with conventional cultivation. A systematic study also showed that among the SRI components, the major effect was by weeder-use followed by single seedling per hill. SRI India
SRI has been introduced in Tamil Nadu in the early 2000s. However, a similar practise has been developed by local farmers over a century ago. Single-seedling methods and the Gaja methods have been known by farmers for a long time. The main difference between Gaja practises and SRI is that the seedlings are transplanted when mature in Gaja compared to young seedlings in SRI.
Today SRI is known to many rice farmers of Tamil Nadu as ‘Ottrai Natru Nadavu’ (single seedling planting). This recognition has come through SRI. But, to our surprise,
we find that single seedling planting was known100 years ago in Tamil Nadu. […] Single-seedling cultivation appears to have been developed by Mr. Aparanam Pillai (location not known) during 1905-06 season, and the Gaja planting method,
which also included single-seedling planting, was apparently developed by Mr. T.S. Narayanasamy Iyer of Thirukkaruhavur in 1911. Source: SRI Issue 6, 2009