FREQUENTLY ASKED QUESTIONS


    What is SRI?

The System of Rice Intensification -- known as SRI, and as SICA in Latin America --is a management strategy for crop improvement. It is a set of ideas, insights and modified practices based on sound agronomic knowledge for increasing the production of irrigated rice, and now many other crops. SRI does not require or depend on improved or new varieties or on chemical fertilizers and crop protection for getting higher output, even though these can be used with SRI management practices. By reducing farmer inputs of seeds and water, and often even of labor, SRI gives greater returns to available resources of land, labor and capital. This improves farmers' incomes while also being beneficial for the environment. SRI plants are less easily affected by water stress, storm damage, and pests and diseases, as they demonstrate desirable resilience to the growing hazards of climate change. {more detail ..}

    1. What are its key practices?
    2. SRI is based on certain principles that get adapted in practice to local conditions. SRI is most concretely explained in terms of changes recommended for altering certain standard practices for growing rice, but the principles supporting them are always to be kept in mind, understanding more than just the practices. For best results when growing irrigated rice:

      • Transplant young seedlings, preferably 8-12 days old, but at least less than 15 days old. These should be grown in an unflooded nursery and should be removed carefully, with minimum trauma to the roots, and replanted in a field quickly and shallow (1-2 cm)
      • Wide spacing between plants, with seedlings planted singly, one per hill instead of 3-6, and in a square pattern, usually 25 x 25 cm. Plant density is reduced by 80-90%, which gives plant roots and canopies more room to grow and to acquire nutrients and sunlight.
      • Keep the soil in the field moist but not continuously flooded, with intermittent wetting and drying, so that the soil is not saturated, neither anaerobic nor hypoxic, not suffocating plant roots and the aerobic soil organisms which can provide many services to the plants.
      • Control weeds with frequent use of a mechanical hand weeder as this aerates the soil. This can enhance yields by 1-2 tons/hectare, stimulating root growth and soil organisms.
      • Enhance soil organic matter as much as possible, adding compost or other biomass that will enhance soil structure and functioning as well as provide balanced nutrition.
      • Enhance soil organic matter as much as possible, adding compost or other biomass that will enhance soil structure and functioning as well as provide balanced nutrition.

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    1. Why isn't SRI considered as a new 'technology'?
    2. SRI is not based on material inputs like most other agricultural technologies. Rather it involves mental changes and new thinking. Also, SRI is a work in progress, continuing to evolve. Promoting something as a technology makes the innovation seem static, with farmers becoming adopters rather than adapters. With SRI, one emphasizes adaptation and continuing improvement by farmers and others {more detail ..}

    Where are the origins of SRI?

SRI was developed in Madagascar by a French priest, Father Henri de Laulanié, S.J., who spent 34 years (1961-1995) working with farmers there to help them improve their rice productivity and their rural livelihoods without needing to rely on purchased inputs. The main practices were synthesized by the 1983-84 season. With Malagasy friends, Laulanié established Association Tefy Saina, a local NGO, in 1990. ATS has promoted SRI knowledge and its use as part of a holistic rural development strategy. {more detail ..}

    1. How has SRI spread around the world?
    2. In 1994, Tefy Saina and the Cornell International Institute for Food, Agriculture and Development (CIIFAD) began working together on a USAID-funded project to conserve the rain forest ecosystems of Ranomafana. Farmers living and cultivating around the park -- with paddy yields usually about 2 tons/ha – by using SRI methods were able to attain average yields of 8 tons/ha, with some having even higher yields. They were planting the same varieties, on the same poor soils, using less water, and not using chemical fertilizer or other inputs, relying instead on use of compost to improve soil fertility. After three years of such results, CIIFAD began trying to get rice scientists in other countries to try out SRI methods; however, it took two years before this began. The higher productivity attainable with SRI management practices was first validated outside Madagascar in China and Indonesia in 1999-2000. Then similar results were reported from Cambodia, Philippines, Cuba, Sri Lanka, India, Myanmar, Gambia, Sierra Leone, and other countries. By 2002, SRI methods had been further validated in 15 countries; 11 years later, there are 51. {more detail ..}

    How does SRI benefit poor households?

Poor households have usually very little access to land, so raising yield per unit area is of great importance. As they have relatively more labor, initial labor-intensity is not as much of a problem for them as it is for larger-scale farmers. However, very poor households with a hand-to-mouth existence may find their family labor constrained for SRI. As noted below, for many farmers, SRI is or becomes also labor-saving. This is good for most farmers, although it could reduce employment for those depending on agricultural wage labor for household income. Keeping rice prices lower by having rice supply available in greater abundance -- and not having supply sharply reduced in seasons with a poor harvest -- is one of the greatest boons that poor households will have from SRI. {more detail ..}

    1. Can SRI also benefit larger farmers?
    2. Yes, because SRI is capitalizing on biological processes and potentials that already exist in rice genomes and in plant-soil-microbial interactions. Its benefits are thus scale-neutral. They are available to any producers who make appropriate adaptations in practices to suit their own conditions. Efforts to mechanize various operations in SRI practice are going on several countries. We expect that SRI ideas will soon be utilized across a full range of scales as well as a wide range of agroecosystems. {more detail ..}

    Can SRI outperform what rice scientists consider 'best management practices'?

It has been argued that SRI only improves upon 'unimproved' farmer practices, not upon the best practices that rice scientists can propose. Now that a farmer in Bihar state of India has set a new world record with an SRI paddy yield of 22.4 tons/ha, calculated by state technicians with hundreds of observers, there is no reason to continue arguing that SRI offers 'nothing new' or 'no new opportunities.' {more detail ..}

    How can SRI benefit the environment?

SRI methods are not only beneficial for people, but also for the natural habitat and for the maintenance of biodiversity.

  • The most direct environmental benefit of SRI is through reductions in water requirements for irrigated rice production. Rice is the 'thirstiest' crop in the world when conventional rice-growing methods are used with their continuous flooding of rice fields. Several thousand liters of water are usually required to produce 1 kg of rice. SRI's water management methods can reduce this 'thirst' by 25 to 50%, and sometimes by more, depending on previous practice and on soil type. The realization that rice does not require flooding, and does not produce its best when grown in standing water, comes as quite a surprise to many persons, who have accepted the conventional wisdom that flooding is beneficial, even necessary. However, that belief is simply wrong, as shown by much research (Guerra et al. 1998).
  • Because SRI methods do not require chemical fertilizer, farmers can reduce their fertilizer applications, or can eliminate these altogether, producing yields as good as, or better than, when using compost and/or other organic inputs. This reduction in agrochemical use can contribute both to better soil and water quality and to improved soil and human health.
  • Not all farmers are willing to switch to fully organic fertilization; but SRI training and experience encourage farmers to reduce their use of chemical fertilizer. For many soils, some combination of organic and inorganic nutrient sources may be optimal (integrated nutrient management, INM). INM may often give the highest SRI yield, but when considering the costs of inputs, it may not necessarily be the most profitable.
  • An evaluation of 120 farmers in Cambodia who had used SRI methods for three years -- with a doubling of their yields -- documented that these farmers had reduced their fertilizer use by 43% and their use of agrochemical protection by 80% (Tech 2004).
  • When SRI was introduced to farmers in eastern Indonesia under a Japanese-funded project, farmers were advised to cut their applications of fertilizer (NPK) by 50%, compared to what was being recommended by the government. With this reduction in fertilizer use and with a 40% reduction in water applications, farmers increased their yields on average by 78% (3.3 tons/ hectare). These data are from 12,133 on-farm comparison trials over six seasons, covering a total area of 9,429 hectares (Sato and Uphoff 2007).
  • A study of SRI effects conducted at Kangwon National University in Korea found significant reductions in pollutants in the water runoff from paddy fields. There were significant reductions in suspended solids (SS), chemical oxygen demand (COD), and total phosphorus (TP). Biochemical oxygen demand (BOD) and total nitrogen (TN) were also reduced, but not significantly. With this, water requirements were reduced by 56% (Choi et al. 2012).
  • Wherever SRI raises paddy yields by reducing fertilizer use, this can improve air, soil and water quality as applied nitrogen not taken up by rice plants, commonly 60-70% of what is applied in paddies, will accumulate in the groundwater or be volatilized into the atmosphere:

  • In some rice-growing areas of China, the levels of nitrate in the groundwater supply are already many times higher than the maximum acceptable level established by the US-EPA. In some communities, nitrate levels in groundwater supply were measured as 300 parts per million (ppm) and some as high as 500 ppm where N fertilizer as being heavily used (Hatfield and Prueger 2004). The US-EPA's allowable NO3 concentration in groundwater is 50 ppm.

Because SRI methods increase rice plants' inherent resistance to pests and diseases, farmers can reduce or even eliminate their use of agrochemicals, many of which have adverse effects on soil and water quality and on human health, both on the health of those who apply them and of that of persons who consume the rice produced.

  • An evaluation of SRI in Vietnam in 2005-06 by the Ministry of Agriculture's National Integrated Pest Management (IPM) Program found that with SRI management, the prevalence of major pests and disease was reduced by 40 to 80%, and the number of sprayings per crop was cut from 2.75 to 1.25 (Dung 2007).
  • The environment can thus benefit from SRI management by extraction of less water from natural ecosystems, and by reductions in the application of chemical fertilizers and sprays. The latter benefits can also contribute to human health.

  • Further, SRI methods can contribute to the conservation of biodiversity. This is most direct and most obvious with respect to the biodiversity of rice species. SRI can make local or traditional varieties more productive, profitable, and thus competitive with high-yielding varieties and hybrids (see FAQ #8). The soil and water management practices of SRI, including the increase of soil organic matter, should have positive impacts of biodiversity of the soil biota, a kind of biodiversity that receives little attention. Beyond this, farmers in Vietnam report that with SRI management there is a revival of populations of fish, frogs and other fauna in their irrigation channels and canals (Castillo et al. 2012). This has economic as well as other benefits for them.
  • SRI has been used in the peripheral zones of national parks and protected areas in Madagascar and Indonesia to help save rain forest ecosystems, giving farmers an attractive alternative to slash-and-burn cultivation, so that habitat can be preserved for much-admired endangered species: lemurs, orangutans, chameleons, and various endemic birds, reptiles and amphibians. By raising the productivity of rice farming systems in marginal areas, SRI can buffer the conflicts between parks and people, reducing human pressures to exploit natural resources in vulnerable ecosystems.
    1. What is the impact of SRI on greenhouse gases?
    2. Because SRI stops continuous flooding of rice paddies, there is no disagreement that it can reduce the emission of methane (CH4) from rice fields. With no flooding, an increase in nitrous oxide (N2O), a more potent greenhouse gas, might be expected. However, when soil is fertilized with organic material rather than inorganic fertilizer, there is less nitrogen (N) available for microbes to convert to N2O. Evaluations in Nepal and Korea have found that with SRI management, there was a reduction in N2O rather than its increase that offset decreases in CH4. Evaluations have not been done on SRI impacts on the 'carbon footprint' of rice production. With less production, transport and use of chemical fertilizer, emissions of CO2 from rice growing should be less. {more detail ..}

    1. Does SRI have anything to do with genetically-modified organisms (GMOs)?
    2. SRI gains are achieved through modifications in crop management, not derived from any particular genetic traits, although we find, understandably, that under SRI management some genotypes perform better than others. SRI is an alternative to, or competitive with, GMOs only insofar as its yield improvements and other beneficial effects are greater than can be achieved by modifying plants' genetic traits. SRI's benefits are already available, without further research, entail little cost, and raise no evident environmental issues. In this way SRI results make the development and use of GMOs less urgent for meeting world food needs. {more detail ..}

    What are the requirements for practicing SRI?

As noted already, SRI does not require a change in rice varieties or the purchase of fertilizers or agrochemical protectants. It does require water control -- so that smaller amounts of water can be provided reliably during the growing season; all crops require at least some water. There must also be sufficient labor available for skilled crop management and enough access to biomass (starting with rice straw) to make compost or do mulching to maintain soil organic matter. Although SRI plants are usually more resistant to pests and diseases, some crop protection measures may be needed, such as IPM or organic pesticides. Having access to a weeding implement to control weeds and to aerate the soil will enhance crop yield. Most important are motivation and aptitude for careful crop management as SRI is more a mental than a material innovation. {more detail ..}

    1. What are the limitations for utilizing SRI methods?
    2. Where there is not sufficient water and water control for maintaining aerobic but moist soil conditions, good SRI results will not be obtained, although the control need not be perfect. Insufficient labor time and skill can also be a constraint. Certain crop pests can limit SRI uitility, e.g., yield will be reduced if root-feeding nematodes are endemic and thrive in unflooded soils. Temperatures must be within an appropriate range for rice crop growth. Part of the SRI methodology is to make appropriate adjustments to deal with limitations such as these, like raised beds within paddies where water control is limited, or modifying irrigation schedules to cope with nematodes. {more detail ..}

    What are the reasons for changing current rice-growing practices?

There are good agronomic justifications for each of the recommended practices. Farmers should learn the principles that justify the practices, not just the practices themselves. Close spacing of rice plants, for example, prevents some of the plant's leaves from getting enough sunlight for photosynthesis. Also, it is the lower leaves that send most of the carbohydrates (energy) to the roots for carrying out their metabolic processes. So, crowding plants together reduces their production of energy for supporting plant growth and grain production, and it also deprives the roots of the energy that they need for their functioning. Simple agronomy. {more detail ..}

    What are the main economic, social and other benefits with SRI?

The most evident benefit is increased yield per hectare; but more important is the higher factor productivity from labor, water and capital investment.

  • Water saving in irrigated rice production and lower costs of production are also very important benefits for farmers.
  • Also, there is no need to make any purchases if farmers are able to make and apply sufficient compost.
  • Higher returns to labor, per hour or day, are also important, as is reduction in labor requirements, including for women, once SRI methods have been mastered.
  • Increased net farmer income and the greater profitability of rice production are quantifiable economic benefits, as is reduced risk of economic loss, seen from evaluations of SRI done for GTZ and IWMI.

Because rice plants are more robust, there are reduced losses to pest and disease and also greater resistance to climate hazards such as drought and storm damage which are becoming more frequent and severe with climate change. More resistance of lodging (being knocked down by wind and/or rain) is an important feature with weather events becoming more extreme. Reduction in greenhouse gas emissions has been discussed above.

  • Other environmental benefits include lower water consumption which reduces the agriculture sector's competition with natural ecosystems, and better soil and water quality from reduced use of agrochemical inputs. These effects should improve environmental quality while also contributing to conservation of biodiversity.
  • SRI management usually shortens the crop cycle by 1-2 weeks with higher yield; this frees up land for other uses and reduces crops' exposure to biotic and abiotic stresses.
  • When SRI paddy (unmilled rice) is milled, there is usually higher outturn of polished rice, by 10-20%, which further adds to food production. Grain quality is commonly enhanced by SRI management, e.g., grain chalkiness is reduced.

These many benefits have contributed to the idea that SRI is 'too good to be true.' But it is. {more detail ..}

    Is there need for any new or special rice varieties with SRI?

No. SRI methods have been found to enhance yield from practically all rice varieties with which they have been used -- high-yielding or traditional, improved or unimproved, hybrids or landraces -- although some varieties respond better than others to SRI modifications in crop management. {more detail ..}

    Does SRI require more labor?

Not necessarily. While the new methods of management are being learned, more time is taken to complete the operations, so SRI is often considered to be 'labor-intensive.' However, labor requirements per hectare usually decline as experience and confidence are gained. The length and steepness of the learning curve varies. In countries where rice farmers are used to making adaptations in practices, such as India and China, and where their rice production is already relatively labor-intensive, farmers report first-season reductions in the number of days of labor per hectare required for use of SRI. {more detail ..}

    What are the gender implications of SRI?

This will depend on what is the prevailing gender division of labor in rice production in the local situation. Most reports have said that women's labor burden has been reduced when SRI is introduced, because rice transplanting becomes quicker once the new methods are learned because plant populations are reduced by 80-90%, and because men often take over the task of weeding (often culturally classified as women's work) when mechanical weeding (classified as men's work) is introduced. There are also some health benefits reported from India and the Philippines. {more detail ..}

    Is SRI an 'organic' system of production?

Not necessarily. SRI was initially developed with chemical fertilizer, but Fr. Laulanié switched to recommending reliance on compost when subsidies for fertilizer were withdrawn, and poor farmers could no longer afford it. Factorial trials have shown organic fertilization, with the other SRI practices, outperforming the use of inorganic fertilizer. However, highest yields may come with some optimizing combination of both sources of nutrients for the soil, in what is called integrated nutrient management (INM). Farmers will decide whether to grow SRI rice organically or not depending on labor availability and cost relationships (e.g., prevailing prices for fertilizer, and the market prices offered for organic rice).{more detail ..}

    Are there any environments in which SRI cannot succeed?

Where temperatures are too low for growing rice (or excessively hot), SRI will not be feasible. But SRI plants have been seen to tolerate more cold and more heat than conventionally-grown plants. At least some minimum of water must be reliably available, with enough water control to prevent continuous flooding and plant inundation (suffocation of roots). Results have been better on acid or neutral soils than on alkaline soils; and saline soils are a problem for all rice crops. Sufficient compost can neutralize the adverse effects of salinity in many instances. Average SRI yields of 9 tons/ha are reported from the cold climates and high elevations of northern Afghanistan and from the Timbuktu region of Mali on the edge of the Sahara Desert. So SRI methods are adaptable to a rather wide range of growing environments if not to all. {more detail ..}

    Can SRI succeed without irrigation?

SRI was developed to improve production of irrigated rice, but NGOs and farmers have adapted SRI methods to upland or rainfed cultivation in the southern Philippines, northern Myanmar, and eastern India, in some places with yields of 7 tons/ha. Water management, timing, and spacing need to be adjusted; but SRI principles have been found to be adaptable to growing rice without irrigation. {more detail ..}

    Can SRI concepts and practices be applied also to other crops?

One of the most promising developments with SRI practice is the extension or extrapolation of its concepts and methods, making appropriate modifications in accordance with SRI principles, to a wide range of other crops: wheat, finger millet, sugarcane, mustard, teff, legumes (black, green and red gram, and soya), and vegetables (tomatoes, chillies, eggplant), even rhizome crops like turmeric and ginger. A world-record potato yield in Bihar state of India has been 'inspired' by SRI experience in the farmer's village, and farmers in Cambodia and in Jharkhand state of India have adapted SRI concepts to improve their production, respectively, of chickens and of lac. The latter is an entomological crop, so it is good to see farmers 'thinking outside the box.' {more detail ..}

    What is the significance of phyllochrons?

The profuse tillering of SRI rice plants can be explained in part by understanding the pattern and extent of tiller and root emergence in rice as in other grass-family crops (wheat, barley). The phyllochron concept was developed in Japan before World War II, but has not been paid much attention by non-Japanese scientists. {more detail ..}

    Are there significant problems of disadoption?

An early report (2003) from Madagascar identified disadoption among very poor households, not able to afford investment of family labor in SRI even if they knew this could give them higher yield, as a barrier to the spread of SRI. Disadoption has been reported in some states of India where irrigation water or rainfall is not reliable enough to risk starting a crop with young seedlings. In Southeast Asia, snails have been a deterrent to continuing with SRI practices, as some farmers find solutions to control this pest, and others are not successful. Where disadoption has been studied, in most cases it has been at most a few percent, usually attributable to factors beyond farmer control. {more detail ..}

    How has SRI been disseminated within and among countries?

For the most part, SRI has been spread by a growing network of interested persons and institutions, from NGOs, from universities or research institutions, sometimes from government agencies or the private sector, and most of all at the grassroots by farmers themselves. The SRI website maintained at Cornell University by the SRI International Network and Resources Center (SRI-Rice) (http://sri.ciifad.cornell.edu) has supported widespread distribution of information on SRI -- experience, problems, solutions, innovations, etc. -- with voluminous email communication among members of the international network. The Better U Foundation supports the work of SRI-Rice to catalyze worldwide spread of SRI ideas and practice; and within many countries, networks of SRI users and proponents have been formed, with their own list-serves or websites or blogs. Information is all freely available, with no IPR or other restrictions. {more detail ..}

    What has been the response of scientists and policy makers?

Initially there was skepticism regarding the higher yields reported with reduction in inputs, without using new or improved varieties. A number of critical articles were published in the mid-2000s, but the push-back against SRI has been diminishing as more and more agricultural scientists have taken an interest in SRI, particularly in China and India, documenting the effects of SRI management and the merits of its component practices. There are now almost 400 published scientific articles on SRI: http://sri.ciifad.cornell.edu/research/index.html SRI has received endorsements by the presidents of the World Bank and of the International Fund for Agricultural Development (IFAD), and the administrator of USAID, among others. The World Bank Institute has produced a toolkit for SRI that is available on line: http://info.worldbank.org/etools/docs/library/245848/overview.html Governments in China, India, Indonesia, Vietnam and Cambodia -- where two-thirds of the world's rice is produced -- are now supporting SRI dissemination, encouraged by their own good results. There should not be much controversy about SRI any more, although more research is still to be done to understand the potentials and limitations of SRI better. {more detail ..}

    What are future directions for SRI?

The ideas that created SRI and their applications will continue to evolve, being applied to many crops beyond rice. We anticipate a convergence between SRI practice and conservation agriculture (Sharif 2011). The initiative and innovation from farmers to modify their crop management should continue, with productive cooperation among farmers, researchers, extensionists, government agencies, and the private sector, quite possibly transforming the current 'linear' model of agricultural development. {more detail ..}