Home  >>  Define SRI

Define SRI (System of Rice Intensification)

Dear Friends,

It has become a fashion now to say that they are cultivating/ promoting SRI method of paddy cultivation. The fascinating figures that appear in the newspapers about the area under SRI and the productivity may fail to justify the total rice production in the district/ state/ country. Certainly, the word SRI has spread but it is doubtful whether SRI has spread in India as projected by the officials in the media.

For this, first of all It is essential to define "SRI". There are standard definitions for Organic Farming, Sustainable Agriculture, Permaculture, Biodynamic Farming, etc.. Is there any such definition for SRI which has been widely accepted. Kindly inform us about the definitions that are available about SRI.

With warm regards

A.R. Natarajan
23rd November, 2010

Dr. Norman Uphoff's response
24th November, 2010

Dear SRI Colleagues,

I thank Ms. Natarajan for raising this question (above). If I were to force myself to ‘define’ SRI, in what would be necessarily a reductionist manner, I would consider a rice crop as qualifying as ‘SRI’ if it has the following three (or four) characteristics at a minimum:

A) If farmers have previously flooded/irrigated their rice crop (note: there are versions of SRI for upland, rainfed cultivation), then SRI management means (1) REDUCTION IN WATER APPLICATIONS, through small/smaller daily applications, or through alternative wetting and drying, and (2) at least during the vegetative growth stage, MAINTAINING PADDY SOIL IN MOSTLY OR INTERMITTENTLY AEROBIC CONDITIONS. Any SRI farmer should be moving toward applying ‘a minimum of water’ (to use Fr. de Laulanie’s phrase) to promote root growth and health and also aerobic soil organisms. How much less water? When applied? These are matters to be worked out according to soil conditions, climate, and time/labor constraints. SRI MEANS LESS WATER USE. There are, as noted above, also rainfed or unirrigated versions of SRI, where farmers have no control over supply of water. Still, SRI farmers in upland areas will take steps to ensure that the roots of young rice plants do not suffocate and degrade because of standing water. They are trying to ‘grow roots’ under rainfed conditions, so that their riceplants can utilize water available in lower soil horizons. So, a first requirement for SRI is altered water management.

B) SRI means GREATLY REDUCED PLANT POPULATIONS, lower by at least two-thirds, and even by 80-90%. This means planting SINGLE SEEDLINGS per hill, or at most two seedlings. (We know that In low-fertility soil, two seedlings will give higher yield than single seedlings; however, in soil with average fertility and certainly with high fertility, single seedlings (if +young and unflooded) will outperform clumps of seedlings.) SRI ACCORDINGLY MEANS WIDER SPACING between hills, preferably in a square pattern to expose plants maximally to the sun and air. (Some variations include rectangular planting or some other geometric shape, one variation being ‘triangular planting’ with three plants per hill with a reduced number of hills, and with 7-10 cm spacing between the three plants place in a triangular pattern.) This wider spacing contributes to greater growth of both roots and canopies.

C) If the crop is established by transplanting (there other variants without transplanting, but transplanting is still the major methodology), SRI MEANS YOUNGER SEEDLINGS, preferably 8-12 days old, at their 2-3 leaf stage of growth, and not more than 15 days of age as a rule. However, in some circumstances (e.g., cold temperature), ‘young seedlings’ can be as old as 20 days. Should a crop not be considered as ‘SRI’ if the farmer does A) and B) but uses 25-day seedlings, when he/she previously planted 30 or 40-day seedlings? Perhaps there was labor shortage or water shortages that delayed transplanting. I think that in such a case, moving to ‘younger seedlings’ even if they are not as young as 8-12 days, is still consistent with SRI.

Sometimes farmers do not have control over their water supply, but are doing their best to reduce their water applications, to give plants more aeration than with conventional practice. How can anyone say how much reduction in water application qualifies as ‘SRI’? Even some reduction could enhance yield (although not by as much as if the farmer has better water control) and also could reduce water demand. If the farmer gets better yield by using less water, that would be sufficient for me to consider this crop as ‘SRI,’ since I understand SRI more as a matter of degree than of kind. I know why many SRI colleagues want to be able to make absolute/qualitative/classificatory/binary statements about ‘what is SRI?’ But I think that this question is in a way a violation of the spirit of SRI, and represents a kind of thinking that will ultimately diminish the positive impacts of the principles and insights that constitute what we generally, without any hard and fast definition, understand as ‘SRI.’

Must farmers use mechanical weeders for their crop to qualify as ‘SRI’? I don’t think so. A), B) and C) above seem to me to be the crux of SRI – use of less water, less seeds, and younger seedlings. We could add that CAREFUL, QUICK AND SHALLOW TRANSPLANTING is also part of ‘SRI.’ But if a farmer is going to use young seedlings, these changes in plant management are practically necessary to get good results. So this seems not necessary to state as a defining characteristic. If farmers do hand weeding because they do not have access to a weeder, but they transplant young seedlings quickly, carefully, singly, in a square pattern, and apply less water more carefully, that to my mind qualifies as ‘SRI.’ If a farmer uses herbicide to control weeds because he/she doesn’t have enough labor to do manual weeding (and/or has no access to a mechanical weeder), this also could be ‘SRI,’ though would not be ‘organic SRI.’

I do not regard organic fertilization as necessary for ‘SRI,’ and neither did Fr. de Laulanie. He developed SRI in the 1980s using chemical fertilizer. When he and the farmers working with him tried using compost instead of fertilizer, when the price of fertilizer escalated after fertilizer subsidies were stopped, the crop results were even better, they found. Organic fertilization is a necessary qualification for ‘Organic SRI,’ which is a special kind of SRI, for which chemical herbicides or insecticides are not used either. Shuichi Sato in his Indonesia SRI work distinguished between ‘Basic SRI,’ which is most or all of the other SRI practices together with a 50% reduction in chemical fertilizer and the increase of organic fertilization, from ‘Organic SRI,’ and promoted the latter personally at the same time his Japanese-funded project promoted the former. Both can coexist, leaving the choice to farmers.

I would be agreeable to stating a fourth defining characteristic of SRI this way:

D) INCREASED APPLICATION OF ORGANIC MATTER to the paddy soil, to improve the soil’s structure and functioning and to enhance the populations of soil biota. It makes sense to expect that SRI practice should include some increase in organic fertilization, but it need not completely replace chemical fertilizer, unless one is intent on practicing ‘Organic SRI.’

Do these ideas help? I don’t know. They are not a short and simple list, which was hoped for. The above discussion can be condensed to say that SRI is, operationally:

    Vietnamese colleagues might refer to this as ‘three lesses and one more.’ To this should be added two statements:
    (i) SRI practice benefits from TRANSPLANTING done very quickly and carefully, to create minimum transplant shock (although various kinds of direct-seeding or mechanical transplanting are being developed that make tradeoffs in absolute productivity for the sake of labor saving). Also,
    (ii) SRI practice benefits from ACTIVE SOIL AERATION by using a mechanical weeder that controls weeds mechanically and enhances root/plant growth. This is very important, adding 1-3 t/ha to yield, but it is not necessary for benefits from the other practices.

These practices together and separately will lead to rice plants that have deeper, longer-lived ROOT SYSTEMS and to more abundant and diverse SOIL BIOTA, which provide many services and benefits to plant. SRI-grown plants will also be more resistant to pests and diseases, and to drought, storm damage, etc. There is increasing evidence that growing rice crops in this way will contribute to net reductions in GHGs.

Let us keep in mind that SRI has grown and prospered as a force within the agricultural sector, because WE HAVE NOT treated SRI in a reductionist manner. We have not said that ‘SRI is only this,’ or that ‘SRI is always this,’ or that ‘SRI is nothing more than this.’ Such reductionist ways of thinking and speaking are counterproductive in many areas of life, but they are particularly antithetical for SRI, which keeps growing and evolving because it has not been mentally encapsulated.

We do SRI a disservice by ‘playing a numbers game.’ What counts is not ‘how many hectares’ or ‘how many farmers’ should be classified as ‘SRI’ -- but rather, is the productivity of farmers’ efforts being enhanced by their changes in thinking and practice? Is water being saved? Is soil and water quality being enhanced? Are rice crops becoming more secure and more resistant to biotic and abiotic stresses? The four ‘criteria’ suggested above (A-D) I am comfortable with as ‘distilling’ into a few points the experience and wisdom of SRI as a phenomenon. But thinking and language that reduce SRI to only this, or always that, or nothing more than certain practices is, in my view an abomination! If SRI had been conceptualized and communicated in this way from the start, it would have been stillborn -- rather than becoming a vigorous, robust phenomenon to work with.

So here, for what they may be worth, are my thoughts on Natarajan’s question. The question is a legitimate one, in particular because we do not want the ideas and the promise of SRI to be aborted by half-measures or shoddy practices. These could discredit the endeavor, although I don’t think that SRI’s eventual success can be halted any more, only slowed. We have no patent or copyright on SRI, but we do have a self-assumed obligation to try to keep SRI true to the original impetus and ideas, which have showed so much power and resiliency to enhance rice productivity in >40 countries and under a huge range of agroecological conditions. We should not give up this potency casually. But in our efforts to keep a hold on SRI, let us not strangle it.

This ‘cri de coeur’ will surely elicit some responses from others in the SRI community which I hope can lead to some wider shared understandings that can enable us to advance the theory and practice of SRI/SCI/SWI/STI…. Paradoxically, SRI is not just about rice.

Jai SRI.