0208 Implications of the System of Rice Intensification for Sustainable Agriculture


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0208 Implications of the System of Rice Intensification for Sustainable Agriculture

  1. 1. Implications of THE SYSTEM OF RICE INTENSIFICATION for Sustainable Agriculture Minnesota Institute for Sustainable Agriculture, October 28, 2002 Norman Uphoff, Cornell International Institute for Food, Agriculture and Development
  2. 2. More tillers and more than 400 grains per panicle
  3. 3. SRI is something quite remarkable and promising <ul><li>But it is a work in progress -- Qs > As </li></ul><ul><li>SRI appears ‘too good to be true’ -- but there is increasing evidence that it is ‘for real’ </li></ul><ul><li>SRI is being used successfully by </li></ul><ul><ul><li>a growing number of farmers in </li></ul></ul><ul><ul><li>a growing number of countries </li></ul></ul><ul><ul><li>Q: WHAT CAN BE LEARNED FROM SRI? -- the main question today </li></ul></ul>
  4. 4. SRI IS A METHODOLOGY <ul><li>rather than a “TECHNOLOGY” </li></ul><ul><li>-- not a fixed set of techniques </li></ul><ul><li>Different paradigm for rice growing </li></ul><ul><li>which can be explained from the literature </li></ul><ul><li>SRI is basically a set of PRINCIPLES </li></ul><ul><li>that are applied through </li></ul><ul><li>a set of PRACTICES that </li></ul><ul><li>farmers are encouraged to </li></ul><ul><li>adapt to suit their local conditions </li></ul>
  5. 5. Basic idea of SRI is that RICE PLANTS DO BEST <ul><li>(A) When their ROOTS can grow large and deep because they were </li></ul><ul><li>transplanted carefully , i.e., without trauma, and with </li></ul><ul><li>wide spacing between plants; and </li></ul><ul><li>(B) When they can grow in SOIL that is: </li></ul><ul><li>well aerated with abundant and diverse </li></ul><ul><li>soil microbial populations </li></ul>
  6. 6. “ Starting Points” for SRI <ul><li>Transplant young seedlings , 8-15 days, </li></ul><ul><li>quickly and very carefully </li></ul><ul><li>Single plants per hill with wide spacing in a square pattern, 25x25 cm or wider </li></ul><ul><li>No continuous flooding of field during the vegetative growth phase (AWD ok) </li></ul><ul><li>Use rotating hoe early and often (2-4x) </li></ul><ul><li>Application of compost is recommended </li></ul><ul><li>These practices produce very different PHENOTYPE from existing genotypes </li></ul>
  7. 7. OBSERVABLE BENEFITS <ul><li>Average yields about 8 t/ha -- </li></ul><ul><li>twice present world average of 3.8 t/ha </li></ul><ul><li>Maximum yields can be twice this -- 15-16 t/ha, with some over 20 t/ha </li></ul><ul><li>Water requirements reducible by 50% </li></ul><ul><li>Increased factor productivity from land, labor, capital and water (> YIELD) </li></ul><ul><li>Lower costs of production -- this is MOST IMPORTANT FOR FARMERS </li></ul>
  8. 8. LESS OR NO NEED FOR: <ul><li>Changing varieties , though best yields from high-yielding varieties and hybrids -- traditional varieties produce very well </li></ul><ul><li>Chemical fertilizers -- these give very positive yield response with SRI, but best results are obtained from compost </li></ul><ul><li>Agrochemicals – plants more resistant to pests and diseases with SRI methods </li></ul>
  9. 9. ADDITIONAL BENEFITS <ul><li>Seeding rate reduced as much as 90%, 5-10 kg/ha gives more than 50-100 kg </li></ul><ul><li>No lodging because of stronger roots </li></ul><ul><li>Environmentally friendly production due to water saving, no/fewer chemicals </li></ul><ul><li>More accessible to poor households because few capital requirements </li></ul>
  10. 10. DISADVANTAGES / COSTS <ul><li>SRI is more labor-intensive , at least initially -- but can become labor-saving </li></ul><ul><li>SRI requires greater knowledge/skill from farmers to become better decision-makers and managers -- but this contri-butes to human resource development </li></ul><ul><li>SRI requires good water control to get best results, making regular applications of smaller amounts of water -- this can be obtained through investments </li></ul>
  11. 11. SRI is COUNTERINTUITIVE <ul><li>LESS BECOMES MORE -- by utilizing the potentials and dynamics of biology </li></ul><ul><li>Smaller, younger seedlings will give larger, more productive mature plants </li></ul><ul><li>Fewer plants per hill and per m 2 can give more yield </li></ul><ul><li>Half the water can give higher yield </li></ul><ul><li>Fewer or no external inputs are associated with greater output </li></ul><ul><li>New phenotypes from existing genotypes </li></ul>
  12. 12. These are remarkable claims <ul><li>But they reflect experience on farms, more than on experiment stations </li></ul><ul><li>I am not the originator of SRI -- just a proponent for its being evaluated and used wherever it can be appropriate </li></ul><ul><li>Many colleagues are now working on this system -- more than15 countries </li></ul><ul><li>SRI is the due entirely to the work of Fr. Henri de Laulanié, S.J . (1920-1995) </li></ul>
  13. 14. SRI is most actively promoted by Association Tefy Saina <ul><li>NGO established by Fr. De Lalaunié and friends in 1990 </li></ul><ul><li>In 1993, CIIFAD was invited to join a USAID project to give farmers around Ranomafana National Park rain forest some good alternatives to their current slash-and-burn cultivation practices </li></ul><ul><li>Tefy Saina joined CIIFAD in this effort, though not without our (my) skepticism </li></ul>
  14. 16. Initial Experience with SRI <ul><li>Average yield of irrigated rice with standard methods around Ranomafana National Park was about 2 t/ha at the time -- very low </li></ul><ul><li>Previous work by NC State University had gotten average yield of 3 t/ha, max. of 5 t/ha </li></ul><ul><li>CIIFAD would have been satisfied with an increase to 3-5 t/ha -- a doubling of yield </li></ul><ul><li>Tefy Saina helped farmers average 8 t/ha over 1994-1999 period, some yields 16 t/ha </li></ul><ul><li>Farmers in a French project improving small-scale irrigation on the high plateau had same results over same 5-year period </li></ul>
  15. 18. Spread beyond Madagascar <ul><li>Nanjing Agricultural University - 1999 </li></ul><ul><li>Agency for Agricultural Research and Development, Indonesia - 1999-2000 </li></ul><ul><li>Philippines, Cambodia, Sri Lanka, etc. </li></ul><ul><li>China Hybrid Rice Center - 2000-2001 </li></ul><ul><li>International conference, Sanya, China, April 2001 -- 15 countries represented </li></ul>
  16. 19. Reports from Sanya Conference
  17. 20. IDEAS FOR SUST. AGRIC. FROM SRI EXPERIENCE <ul><li>Under appropriate mgmt conditions, TILLERING should be encouraged , not avoided -- provided that plants’ root systems are intact and functioning </li></ul>
  18. 21. In the literature, it is generally reported that there is an inverse relationship between <ul><li>the number of tillers/plant, and </li></ul><ul><li>the number of grains/panicle </li></ul><ul><li>Profuse tillering is thought to be wasteful and thus to be avoided -- “diminishing returns” </li></ul>
  19. 24. The literature reflects conventional, suboptimal growing conditions for rice -(a ‘closed system’ view) <ul><li>Under continuous flooding (hypoxic soil conditions), rice plant roots degenerate </li></ul><ul><li>Rice is not an aquatic plant </li></ul>
  20. 26. Physiology of Rice Roots <ul><li>Under continuously flooded conditions, most rice roots (about 3/4) remain in the top 6 cm of soil (Kirk and Solivas, 1997) </li></ul><ul><li>Under continuously flooded conditions, rice plant roots form aerenchyma (air pockets), losing 30-40% of root cortex </li></ul><ul><li>Under unflooded conditions, neither irrigated nor upland varieties form aerenchyma (Puard et al. 1989) </li></ul>
  21. 28. Soil aeration is important for (a) root survival/growth and (b) soil microbial abundance and biodiversity <ul><li>With SRI practices of plant, soil, water and nutrient management, one gets very different root structure and performance </li></ul>
  22. 29. Evidence on Root System Development/Degeneration <ul><li>Evaluated by ‘pull’ test of root resistance (O’Toole and Soemartono 1981) </li></ul><ul><li>Three plants -- 3-week seedlings, 3/hill, close planting, continuous flooding -- averaged 28 kg/hill (Joelibarison 1998) </li></ul><ul><li>Single SRI plants --12-day seedlings, 1/hill, 25x25 cm, aerated soil - averaged 53 kg/hill -- 5x more resistance/plant </li></ul>
  23. 30. Dry Matter Distribution of Roots in SRI and Conventionally-Grown Plants at Heading Stage (CNRRI research: Tao et al. 2002) Root dry weight (g)
  24. 31. Root Activity in SRI and Conventionally-Grown Rice (Nanjing Agr. Univ. research: Wang et al. 2002) (Wuxianggeng 9 variety)
  25. 33. Conventional View of ROOTS <ul><li>Roots are “a waste” because they lower harvest index (HI) </li></ul><ul><li>Roots are largely ignored in plant science research (cf. standard text on rice) </li></ul><ul><li>We should change this view -- to more synergistic one </li></ul>
  26. 34. Importance of Structural (Qualitative) Analysis, not just Quantitative View <ul><li>Phyllochrons are a good example of the value of going beyond quantitative analysis </li></ul><ul><li>Also there are an example of parochialism in science when it is not truly international </li></ul>
  27. 35. Tillering in rice is regulated by a structural pattern of growth <ul><li>PHYLLOCHRONS apply to all gramineae species; more precise and illuminating than leaf age and degree-days </li></ul><ul><li>Discovered by Katayama (1920s-30s), further developed by de Laulanié (1993) </li></ul><ul><li>Under good growing conditions and if the root system is intact, the number of tillers per rice plant can exceed 100 </li></ul>
  28. 40. What speeds up the biological clock? (adapted from Nemoto et al. 1995) <ul><li>Shorter phyllochrons Longer phyllochrons </li></ul><ul><li>Higher temperatures > cold temperatures </li></ul><ul><li>Wider spacing > crowding of roots/canopy </li></ul><ul><li>More illumination > shading of plants </li></ul><ul><li>Ample nutrients in soil > nutrient deficits </li></ul><ul><li>Soil penetrability > compaction of soil </li></ul><ul><li>Sufficient moisture > drought conditions </li></ul><ul><li>Sufficient oxygen > hypoxic soil conditions </li></ul>
  29. 41. Better growing conditions shorten the phyllochron <ul><li>This means that more phyllochrons of growth can be completed before plant switches from its vegetative growth phase to its reproductive phase </li></ul><ul><li>More tillering means there is also more root development </li></ul>
  30. 43. This is what made it possible to go from 2 t/ha to 8 t/ha <ul><li>A synergistic relationship between root development and tillering </li></ul><ul><li>With both together supporting increased grain filling in panicles </li></ul><ul><li>Having massive root development , </li></ul><ul><li>80% or more effective tillering, </li></ul><ul><li>More filled grains, and </li></ul><ul><li>Higher grain weight </li></ul>
  31. 44. Positive benefits are seen from soil aeration during the vegetative growth period
  32. 45. SRI capitalizes on the fact that the uptake of N is a demand-led process
  33. 46. Paths for Increased Grain Yield in Relation to N Uptake, using QUEFTS Analytical Model (Barison, 2002)
  34. 47. Rapid tillering and root growth <ul><li>SRI creates demand for nutrients -- due to the accelerating plant growth after the first 5-6 weeks </li></ul><ul><li>But where does supply come from? </li></ul><ul><li>Suggest that we need to consider biological processes and sources , not just nutrients “available” in soil </li></ul>
  35. 48. The contributions of soil microbial activity are more important than recognized <ul><li>“ The microbial flora causes a large number of biochemical changes in the soil that largely determine the fertility of the soil.” (DeDatta, 1981, p. 60, emphasis added) </li></ul>
  36. 49. Biological Nitrogen Fixation? <ul><li>BNF can occur with all gramineae species, including rice (Döbereiner 1987, and others) </li></ul><ul><li>In flooded paddies, BNF is limited to anaerobic processes; SRI provides aerobic conditions as well; BNF must be occurring </li></ul><ul><li>Mixing aerobic and anaerobic soil conditions increases BNF (Magdoff and Bouldin 1970) </li></ul><ul><li>Nitrogenase production is suppressed by the use of chemical fertilizers (van Berkum and Sloger 1983) </li></ul>
  37. 50. P SOLUBILIZATION? <ul><li>P solubilization is increased under alternating aerobic and anaerobic soil conditions; Turner and Haygarth (2001) measured large increases in soluble organic P with alternate wetting/drying </li></ul><ul><li>“ Microbiological weathering” is perhaps more important than are geochemical weathering processes? </li></ul><ul><li>Biological weathering processes increase availability of other nutrients? S, Zn, Cu </li></ul>
  38. 51. MYCORRHIZAL Contributions? <ul><li>Fungi cannot grow in anaerobic soil so irrigated rice has forfeited the benefits of mycorrhizae for centuries </li></ul><ul><li>Mycorrhizal fungi can increase volume of soil accessed by root 10 to 100x </li></ul><ul><li>Plants with mycorrhizal associations can grow well with just a fraction of the P supply that “uninfected” plants need </li></ul>
  39. 52. Benefits from Rhizobia in rice now being explored <ul><li>Studied where rice and clover grown in rotation in Egypt, for many centuries </li></ul><ul><li>These endophytic bacteria induce more efficient acquisition of N, P, K, Mg, Ca, Zn, etc. in rice (Yanni et al. 2001) </li></ul><ul><li>Rhizobia increase yield and total protein quantity/ha , by producing auxins and other plant-growth promoting hormones -- however, no BNF demonstrable </li></ul>
  40. 53. ROOT EXUDATION <ul><li>Farmers report that SRI practices improve their soil quality over time -- yields have gone up rather than down with addition of compost -- this is hard to explain with standard soil science </li></ul><ul><li>The soils around Ranomafana were evaluated in chemical terms as some of the poorest in the world (Johnson 1994) e.g., 3-4 ppm P, low CEC all horizons </li></ul>
  41. 54. Larger canopies and root systems increase exudation and rhizodeposition <ul><li>30-60% of C fixed in canopy is sent to the roots, and 20-40% of this exuded or deposited in rhizosphere (Neumann and Römheld 2001, in Pinton et al. 2001) </li></ul><ul><li>Also 20% of plant N is transferred (Brimecombe et al. 2001) </li></ul><ul><li>Roots and shoots are “ two-way streets ” </li></ul><ul><li>We should to apply what we learned in biology classes to our agriculture </li></ul>
  42. 55. SRI Raises More Questions than It Gives ANSWERS <ul><li>This is a PRACTICE-LED innovation </li></ul><ul><li>Scientists have a challenge/opportunity to develop and “retrofit” explanations </li></ul><ul><li>Phenotypical changes are the starting point -- these can surely be explained: </li></ul><ul><ul><li>Greater root growth </li></ul></ul><ul><ul><li>Greater tillering </li></ul></ul><ul><ul><li>Less senescence of roots and canopy </li></ul></ul><ul><ul><li>Positive correlation: tillering x grain filling </li></ul></ul>
  43. 56. Plant Physical Structure and Light Intensity Distribution at Heading Stage (CNRRI Research: Tao et al. 2002)
  44. 57. Suggested Focuses for Explanation of SRI Effects <ul><li>Root development  different transplanting, wider spacing & soil aeration -- try to accelerate </li></ul><ul><li>Soil microbial abundance and activity  plant, soil, water & nutrient management, mixing aerobic / anaerobic conditions </li></ul>
  45. 58. THESE FOCUSES SURELY APPLY TO OTHER PLANTS/CROPS <ul><li>We hope that insights from SRI can help to improve our agriculture in general, in ecological ways </li></ul><ul><li>Need to keep a farming system view, concern with productivity > yield </li></ul><ul><li>Most important, need to be ever more concerned with sustainability </li></ul>
  46. 59. THANK YOU <ul><li>More information is available </li></ul><ul><li>on the SRI WEB PAGE : </li></ul><ul><li>http://ciifad.cornell.edu/sri/ </li></ul><ul><li>including Sanya conference proceedings </li></ul><ul><li>E-MAIL ADDRESSES : </li></ul><ul><li>[email_address] </li></ul><ul><li>[email_address] </li></ul><ul><li>[email_address] </li></ul>