SRI An Opportunity for Improving Food Security in Latin America


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Presenter / Institution: Norman Uphoff, CIIFAD

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SRI An Opportunity for Improving Food Security in Latin America

  1. 1. SRI -- The System of Rice Intensification: An Opportunity for Improving Food Security in Latin America? Norman Uphoff Cornell International Institute for Food, Agriculture and Development (CIIFAD) in cooperation with Association Tefy Saina (ATS)
  2. 2. More tillers and more than 400 grains per panicle
  3. 3. The System of Rice Intensification (SIMA) developed in Madagascar almost 2 decades ago can: <ul><li>Increase rice production -- double yield </li></ul><ul><li>Improve food security esp. for poor HHs, </li></ul><ul><li>Raise total factor productivity, and </li></ul><ul><li>Enhance the environment -- cut demand for water by half, no use of agrochemicals </li></ul>
  4. 4. Sounds too good to be true <ul><li>But SRI is being tried in more and more countries around world. </li></ul><ul><li>The reasons for SRI performance can be explained in scientific terms . </li></ul><ul><li>It should be put to empirical tests , not just rejected on a priori grounds. </li></ul><ul><li>SRI is like the agronomists’ $100 bill on the sidewalk. </li></ul>
  5. 5. SRI capitalizes on potentials that have long existed in the plant’s genetic endowment <ul><li>These potentials have been inhibited by the standard practices for growing irrigated rice. </li></ul><ul><li>SRI proposes managing plants, soil, water and nutrients in new ways . </li></ul><ul><li>These give us a different phenotype from the existing rice genome. </li></ul>
  6. 6. SRI gives an opportunity to raise concurrently the productivity of: <ul><ul><ul><li>Land </li></ul></ul></ul><ul><ul><ul><li>Labor </li></ul></ul></ul><ul><ul><ul><li>Capital </li></ul></ul></ul><ul><ul><ul><li>Water </li></ul></ul></ul><ul><li>Not having to make tradeoffs among them </li></ul><ul><li>Also reduces farmers’ costs of production </li></ul>
  7. 7. SRI changes the ways that farmers have grown irrigated rice for centuries, even millennia, using simple methods . <ul><li>SRI is more accessible to the poor because it does not depend on external inputs -- it requires neither use of new seeds nor application of agrochemicals -- these are optional. </li></ul>
  8. 8. SRI requires only about half as much water per season as when rice is grown in continuously flooded fields <ul><li>SRI may contribute also to reduction in greenhouse gas emissions since rice grown in continuously flooded paddies accounts for about 25% of methane (CH 4 ) going into atmosphere </li></ul>
  9. 9. SRI is COUNTERINTUITIVE , because it enables us to get more from less <ul><li>Higher yields result from: </li></ul><ul><li>Transplanting younger, smaller seedlings </li></ul><ul><li>Fewer plants per hill & per m 2 </li></ul><ul><li>Using less water per season, with </li></ul><ul><li>Less or no need for purchased inputs </li></ul>
  10. 10. <ul><li>There is mounting evidence from a growing number of countries that SRI does indeed have the potentials that were first reported from Madagascar -- now 15 countries. </li></ul><ul><li>Nobody is asked to accept and utilize SRI based just on our reports -- </li></ul><ul><li>Let it be tried and evaluated by both farmers and researchers . </li></ul>
  11. 11. Data from Sanya reports
  12. 12. The main objections against this methodology have been that: <ul><li>SRI requires good water management </li></ul><ul><li>SRI is labor-intensive </li></ul><ul><li>SRI appears “ too good to be true” </li></ul><ul><li>(1) Water control is definitely necessary </li></ul><ul><li>(2) But SRI also gives higher returns to labor, and over time, it can become labor-saving </li></ul><ul><li>(3) Appearing “too good to be true” only means that SRI should be subjected to careful scrutiny </li></ul>
  13. 13. In Madagascar , where yields average 2-2.5 t/ha, 100s of farmers in 2 programs (USAID and French) have averaged 8-9 t/ha over a 5-year period -- on mostly very poor soils.
  14. 14. In China , the first SRI trials at Nanjing Agric. University gave 9.2 to 10.5 t/ha . While these levels can be achieved in China with the best varieties and best techniques, these take twice as much water as applied with SRI. SRI method used with hybrid rice varieties has given yields in the 12-15 t/ha range.
  15. 15. In Cambodia and Myanmar , where conventional yields are even lower than in Madagascar (2 t/ha), farmers using SRI have averaged 5-6 t/ha with NGO guidance.
  16. 16. In Sri Lanka , where the average yield is about 3.5 t/ha, farmers have averaged ~8 t/ha with SRI, with some farmers achieving much higher yields.
  17. 18. In Sri Lanka and Madagascar , some farmers are getting yields in the range of 15 to 20 t/ha once they have mastered the techniques and improved their soil quality. The maximum potential of SRI methodology remains to be fully realized.
  18. 19. <ul><li>SRI effects are seen with all varieties, both traditional and high-yielding. </li></ul><ul><li>Good news for rice breeders is that very best results have come with use of HYVs , e.g., IR15 (11-12 t/ha), IR46 (13.5 t/ha), BG235 (17 t/ha), Tainung 16 (21 t/ha) </li></ul><ul><li>SRI is essentially a set of insights and principles about how to help rice plants achieve more productive phenotypes by realizing genetic potentials in the plant. </li></ul>
  19. 20. The basic PRINCIPLES underlying SRI are: <ul><li>(A) RICE PLANTS WILL PERFORM BETTER WITH: </li></ul><ul><li>Careful transplanting , to minimize trauma, </li></ul><ul><li>Wide spacing , for canopy and root growth, of </li></ul><ul><li>Young seedlings (before 4th phyllochron) so rice plants’ growth potential will be preserved. </li></ul>
  20. 21. (B) RICE WILL PERFORM BETTER IN SOIL that is: <ul><li>Well-aerated during the vegetative growth period, through: </li></ul><ul><li>* careful water management, and </li></ul><ul><li>* mechanical weeding (rotating hoe). </li></ul><ul><li>Enriched microbiologically through </li></ul><ul><li>* compost (SOM), and different (SRI) </li></ul><ul><li>* plant/soil/water/nutrient management. </li></ul>
  21. 22. SRI PRACTICES – to be varied according to local conditions are: <ul><li>Early transplanting -- < 15 days, best between 8-12 days, only two tiny leaves </li></ul><ul><li>Careful transplanting – in 15-30 min., root laid into soil 1-2 cm, shaped like L > J </li></ul><ul><li>Wide spacing – single plants per hill, in a square pattern , 25x25cm, up to 50x50cm </li></ul>
  22. 23. SRI Practices (continued) <ul><li>Well-drained soil during vegetative growth phase – with no continuously standing water – </li></ul><ul><li>either by (a) daily application of small amounts, or (b) alternate wetting and drying (4-5 days) </li></ul><ul><li>After PI, keep a thin layer of water (1-2 cm); and then drain ~15 days before harvesting </li></ul><ul><li>Early and frequent weeding , start 10-12 DAT; up to 4 times, using a “rotating hoe” </li></ul><ul><li>Nutrient amendments are recommended – with compost preferred over chemical fertilizer, best applied to the preceding crop </li></ul>
  23. 29. .
  24. 31. RESULTS of SRI Practices <ul><li>These practices lead to synergistic </li></ul><ul><li>(a) Root development with increased </li></ul><ul><li>(b) Increased tillering, supporting </li></ul><ul><li>(c) Greater grain filling. </li></ul><ul><li>There appears also to be greater </li></ul><ul><li>(d) Resistance to pests and diseases </li></ul>
  25. 32. OBSERVABLE PHENOTYPICAL CHANGES attributable to SRI <ul><li>More tillers/plant -- 30-50, even 100+ </li></ul><ul><li>Larger root systems – root pulling resistance of 28 kg /clump for 3 plants grown conventionally vs. 53 kg /plant for single SRI plants -- >5x per plant </li></ul><ul><li>Positive correlation tillers/plant and grains/panicle – no lodging </li></ul>
  26. 33. Comparison of high-yield rice in tropical and subtropical environments: I: Determinants of grain and dry matter yields J. Ying, S. Peng, Q. He, H. Yang, C. Yang, R. M. Visperas, K. G. Cassman, Field Crops Research , 57 (1998), p. 72. <ul><li>“… a strong compensation mechanism exists between the two yield components [panicle number and panicle size]” with a “ strong negative relationship between the two components…” (emphasis added) </li></ul>
  27. 35. Rice is not an aquatic plant <ul><li>The standard understanding of rice is that: </li></ul><ul><li>“ Rice thrives on land that is water-saturated or even submerged during part or all of its growth cycle.” (p. 43) </li></ul><ul><li>“ Most varieties maintain better growth and produce higher grain yields when grown in flooded soil than when grown in unflooded soil.” (pp. 297-298). </li></ul><ul><li>S. K. DeDatta, The Principles and Practices of Rice Production , J. W. Wiley, NY, 1981. </li></ul>
  28. 36. <ul><li>But in flooded (hypoxic) soil, rice roots remain close to the surface. At 29 DAT, about ¾ are in top 6 cm of soil (Kirk and Solivas 1997) </li></ul><ul><li>Rice plant roots grown in flooded soil form aerenchyma (air pockets) through disintegration of the cortex which is “often almost total…[after PI] the main body of the root system is largely degraded and seems unlikely to be very active in nutrient uptake” (Kirk and Bouldin 1991) </li></ul><ul><li>Yet in unflooded soil neither irrigated nor upland varieties form aerenchyma (Puard et al. 1989) </li></ul>
  29. 37. Root cross-sections for upland (left) and irrigated (right) varieties -- ORSTOM research by Puard et al. (1989)
  30. 38. Abstract <ul><li>Nature and growth pattern of rice root system under submerged and unsaturated conditions </li></ul><ul><li>S. Kar, S. B. Varade, T. K. Subramanyam, and B. P. Ghildyal, </li></ul><ul><li>Il Riso (Italy), 1974, 23:2, 173-179 </li></ul><ul><li>Plants of the rice cultivar Taichung (Native) were grown in pots of sandy loam under 2 water regimes in an attempt to identify critical root-growth phases. Observations on root number, length, volume and dry weight were made at early tillering, active tillering, maximum tillering, and reproductive stages. </li></ul><ul><li>Rice root degeneration , normally unique to submerged conditions , increased with advance in plant growth. At flowering, 78% had degenerated . During the first phase under flooding, and throughout the growth period under unsaturated conditions, roots rarely degenerated. </li></ul>
  31. 39. Explanation of tiller and root growth in terms of phyllochrons <ul><li>These are periodic intervals of plant growth common to all the gramineae species -- in rice, a phyllochron is usually from ~5-8 days </li></ul><ul><li>During each phyllochron , the plant produces from its apical meristem 1 or more phytomers (phytomer = a unit of a tiller, a leaf and a root) </li></ul><ul><li>Phyllochrons represent biological rather than calendar time – they are lengthened/shortened by a number of factors that can slow down or speed up the plant’s “biological clock” </li></ul>
  32. 42. Speeding up the biological clock <ul><li>Higher temperature vs. cold temperatures </li></ul><ul><li>Wider spacing vs. root/canopy crowding </li></ul><ul><li>More solar radiation vs. shade </li></ul><ul><li>Ample nutrients in soil vs. nutrient deficits </li></ul><ul><li>Soil penetrability vs. soil compaction </li></ul><ul><li>Sufficient moisture vs. drought conditions </li></ul><ul><li>Sufficient oxygen vs. hypoxic conditions </li></ul>
  33. 43. Evidence of Synergy <ul><li>Factorial trials by Faculty of Agriculture students at Univ. of Antananarivo, under contrasting agroecological conditions : </li></ul><ul><li>West coast near Morondava, 2000: </li></ul><ul><li>hot, dry climate, poor sandy soils, ~100m </li></ul><ul><li>High plateau at Anjomakely, 2001: </li></ul><ul><li>temperate climate, better soils, ~1200m </li></ul>
  34. 44. Evaluating Six Factors <ul><li>Variety: HYV (2798) vs. local (riz rouge) or Soil quality: clay (better) vs. loam (poor) </li></ul><ul><li>Water mgmt: aerated vs. saturated soil </li></ul><ul><li>Seedling age: 8 days vs. 16 or 20 days </li></ul><ul><li>Plants per hill: 1/hill vs. 3/hill </li></ul><ul><li>Fertilization: compost vs. NPK vs. none </li></ul><ul><li>Spacing: 25x25cm vs. 30x30cm (NS diff.) </li></ul><ul><li>6 replications: 2.5x2.5m plots (N=288, 240) </li></ul>
  35. 47. Value of Soil Aeration ? <ul><li>Data from 76 farmers at Ambatovaky, 1997-98 season </li></ul><ul><li>Yield differentials analyzed according to number of weedings with “rotary hoe” </li></ul><ul><li>Similar effect of weeding in data from thesis by Frederic Bonlieu (Univ of Anjers) </li></ul><ul><li>1 weeding = 4.2 t/ha, 2 weedings – 4.4 t/ha </li></ul><ul><li>3 weedings = 5.1 t/ha ($20 yields $210?) </li></ul>
  36. 49. Emergent Concerns from SRI <ul><li>Importance of ROOTS </li></ul><ul><li>DeDatta book on rice (1981): in chapter on the “morphology, growth and development of the rice plant” -- only 8 out of 390 lines of text on roots, and in 16-page index with 1,100 entries, </li></ul><ul><li>not even one entry on roots – “roots a waste”? </li></ul><ul><li>Importance of SOIL MICROBIOLOGY </li></ul><ul><li>-- presently ignoring exudates, mycorrhizae, etc. </li></ul>
  37. 50. Root Exudation <ul><li>“ The amount of knowledge available on exudation from rice plants is minute …” (Wassman and Aulakh, 2000) </li></ul><ul><li>Maize grown in a nutrient culture solution exuded three times lower amount of sugars and vitamins than exudation by plants grown in a solid substrate (Schönwitz and Ziegler, 1982) </li></ul>
  38. 51. Root Exudation (cont’d) <ul><li>Exudation can cope with nutrient deficiencies through mobilization of nutrients at the root-soil interface (Nagarajah et al., 1970) </li></ul><ul><li>Plants not only adjust the quantity but also the quality of root exudates, e.g., in the response to deficiencies of Mn and Fe , and in the secretion of nitrogenase (Wassmann and Aulakh, 2000) </li></ul>
  39. 52. Root Exudation (cont’d) <ul><li>Plants under stress commonly increase their exudation rather than decrease it -- against usual expectations (Shigo, 2000) </li></ul><ul><li>Nutrients transported in the phloem are not just stored in plant organs but are given up into the rhizosphere. </li></ul><ul><li>Plants should be understood as “two-way” streets,” not “one-way” streets concerned only with uptake of water and nutrients . </li></ul>
  40. 53. Importance of Microorganisms <ul><li>“ The main biochemical processes in flooded soil can be regarded as a series of successive oxidation-reduction reactions mediated by bacteria… </li></ul><ul><li>“ The microbial flora cause a large number of biochemical changes in the soil that largely determine the fertility of the soil. ” (De Datta, 1981, p. 60, emphasis added) </li></ul>
  41. 54. Uptake of N is Demand-Driven <ul><li>The rate of uptake of N by rice roots is independent of the concentration of N at the roots’ surface (Kirk and Bouldin,1991). </li></ul><ul><li>Rice roots ‘down-regulate’ their transport system for NH 4+ influx and/or ‘up-regulate’ the efflux, thereby exuding ammonium in excess of plant needs (Ladha et al., 1998, emphases added). </li></ul>
  42. 55. Alternative Models for N Uptake <ul><li>Supply-Side Model to Increase Growth </li></ul><ul><li>Apply N to the soil to raise N availability </li></ul><ul><li>This assumes that rice plants will take up more N if it is easier for them to access N because of higher concentrations in the root zone </li></ul><ul><li>Demand-Driven Model for Promoting Growth </li></ul><ul><li>Manage plants in ways that accelerate their rate of growth </li></ul><ul><li>This reflects an under-standing that increased plant demand for N is what induces the roots to take up more N </li></ul>
  43. 56. OBJECTIONS to SRI <ul><li>Slow Spread in Madagascar -- true, but now changing with CRS and government support </li></ul><ul><li>Data from French irrigation project around Antsirabe and Ambositra for period from 1994/95 to 1998/99 (Hirsch, 2000) </li></ul><ul><li>SRI area expanded from 34.5 to 532.8 ha , without an active extension program </li></ul><ul><li>SRI yields averaged 7.91-9.12 t/ha vs. 3.58-3.95 t/ha with recommended package 2.24-2.47 t/ha with peasant practices </li></ul>
  44. 57. Difficulty in Replicating Results <ul><li>SRI has been one of the few agricultural innovations where farmers have often gotten higher yields than researchers </li></ul><ul><li>Usually it is the reverse, that researchers’ results are difficult to replicate on farmers’ fields -- farmers do better with SRI. </li></ul><ul><li>Possible explanations may be found in evaluations of soil microbiology. </li></ul>
  45. 58. SRI is Labor-Intensive <ul><li>SRI does require 25-50% more labor inputs , at least initially -- one study in Madagascar with 109 farmers found a 26% difference; Sri Lankan analysis found an 11% difference </li></ul><ul><li>But SRI time required is reduced as farmers gain skill and confidence; almost always the returns to labor are higher by 25-50% </li></ul><ul><li>Some farmers who have mastered SRI techniques report that they are labor-saving </li></ul>
  46. 59. If farmers are labor-constrained , it is most beneficial economically for them to use SRI on as much of their land as they have enough labor for , to capture higher returns to all their factors of production (land, labor, capital, water), and then to use remaining land for other purposes
  47. 60. SRI is Skill-Intensive <ul><li>Yes, this can be seen as a positive feature , rather than as something negative -- since it is a BENEFIT as well as a COST </li></ul><ul><li>Farmers involved in SRI evaluation and adaptation learn to become more experimental and more innovative </li></ul><ul><li>Being rewarded for unlearning old ways opens up new avenues for development </li></ul>
  49. 62. SRI Needs Better Water Control <ul><li>This is the main requirement and limitation </li></ul><ul><li>There will be many areas where SRI cannot be presently utilized for this reason </li></ul><ul><li>But the greatly increased factor productivity with SRI should make new investments in water control infrastructure profitable </li></ul><ul><li>This kind of investment should attract donors that are interested in food security, poverty reduction, and environmental benefits </li></ul>
  50. 63. There is Not Enough Compost ? <ul><li>But compost is an accelerator , not a requirement </li></ul><ul><li>Most farmers in Madagascar with doubled yields are not using compost -- or NPK </li></ul><ul><li>Most who get tripled yields or more are using compost </li></ul><ul><li>If yields can be increased 2-3x, the returns to labor from making and applying compost can justify growing biomass and harvesting it from non-arable land areas </li></ul>
  51. 64. SRI is Only Good on Small Scale <ul><li>Not a valid objection if poverty reduction is an objective </li></ul><ul><li>There are many millions of small and poor farmers with only 0.25-1.0 hectare of land </li></ul><ul><li>SRI can be scaled up: one early adopter has gone from 0.25 to 8.0 hectares -- now rich </li></ul><ul><li>SRI methods can be adapted to larger scale once the scientific principles are understood; SRI is not a fixed or finished technology </li></ul>
  52. 65. If SRI is So Good, Why Wasn’t SRI Discovered Before? <ul><li>Each of the main practices looks risky </li></ul><ul><li>If a farmer’s family depends on rice harvest: </li></ul><ul><li>Why plant a tiny seedling , not larger one? </li></ul><ul><li>Why plant only one per hill , and not more? </li></ul><ul><li>Why plant just a few plants per m 2 ? </li></ul><ul><li>Why not provide the rice plants with </li></ul><ul><li> as much water as possible? Makes no sense </li></ul><ul><li>SRI fields look terrible for first 4-5 weeks </li></ul>
  53. 66. Practices seem risky, even crazy <ul><li>The chances of someone doing all of these together , at the same time, are negligible </li></ul><ul><li>Actually, some SRI practices such as single plants, well-drained soil, and use of compost have been traditionally used by farmers </li></ul><ul><li>But active soil aeration with promotion of microbial activity needed the rotating hoe </li></ul><ul><li>However, this was used for row planting , which maintains relatively dense spacing </li></ul>
  54. 67. SRI is Still a “Work in Progress” <ul><li>We invite others to join in experimenting with and evaluating these methods. </li></ul><ul><li>Scientific investigations and practical trials by farmers should proceed in parallel, with each contributing to the other . </li></ul><ul><li>Implications of SRI insights and practices should be considered for other crops and for agriculture in general . </li></ul>