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1615 Ecological Intensification - Lessons from SRI from Green Revolution to Agro-Ecology

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1615 Ecological Intensification - Lessons from SRI from Green Revolution to Agro-Ecology

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Author: Willem Stoop
Date: December 2016
Place: Agro-Ecology Group at Brussels University

Author: Willem Stoop
Date: December 2016
Place: Agro-Ecology Group at Brussels University

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1615 Ecological Intensification - Lessons from SRI from Green Revolution to Agro-Ecology

  1. 1. Ecological Intensification Lessons from SRI: from “green revolution” to “agro-ecology” Willem A. Stoop December 2016
  2. 2. Personal Background: Willem A. Stoop (agronomist/soil scientist) • Graduated in 1969 from Wageningen University in Soil Science and fertiliser use. • PhD in 1974: Soil chemistry of tropical soils • 1974- ‘98: Intern. Agric. Research (CGIAR Centers: CIMMYT, ICRISAT, ISNAR, WARDA) Green Revolution agronomy. • 1998 – present: Independent consultant for “Systems of Rice / Crop Intensification (SRI/SCI)” : an Agro-ecological approach
  3. 3. Outline of presentation 1. Approaches towards sustainable intensification: conventional or agro-ecological. 2. System of rice intensification (SRI): brief history; an example of an agro-ecological approach; 3. The set of SRI practices 4. Biologial processes. 5. The controversy with conventional, modern agriculture. 6. Some conclusions
  4. 4. Two approaches towards intensification Conventional (modern) Intensification • Modern varieties • Dense seeding/planting • Irrigation • External inputs : seeds (HYV) and chemicals: fertilisers (NPK); crop protection • Mechanisation/ specialisation Ecological Intensification • Any adapted variety • Low seed rates • Rainfed (irrigated) • Local / internal inputs: landraces , organic fertilisers; bio-diversity / IPM • Diversification: mixed farming
  5. 5. Agro-ecological approach Major characteristics: • The actual landscape: land use types : field observations • The management of natural biological processes: bio-diversity and adaptation • Social Organisation: dialogues with stakeholders (i.e. farmers and others); exchange of knowledge
  6. 6. Uttarkhand (India): terrased wheat fields (light green); used as rice fields in wet season
  7. 7. Madagascar: (rice) field micro diversity and smallholder adaptation
  8. 8. Burkina Faso: Crop adaptation to land types
  9. 9. Management of natural biological processes: adaptation of practices In response to diversity and variability in local: Agro-ecological conditions Socio-economic conditions
  10. 10. The “water” factor: irrigated and natural flooding (top), rainfed uplands and rainfed lowlands in Mali and Burkina
  11. 11. System of rice (crop) intensification (SRI) • Brief history • A set of agronomic practices • Rational for sustainable intensification
  12. 12. Liberia : a good SRI crop
  13. 13. SRI: critical factors • Seed quality (large, bold seeds) • Time / timing : seeding and/or transplanting dates; seedling age • Plant spacing: nb. of plants per m2; planting in rows • Soil moisture regime: alternate wet-and-dry (aerobic) • Soil fertility: soil organic matter • Regular weeding: soil aeration
  14. 14. Rice nurseries Conventional rice nursery of old (about 40 days) plants SRI nursery at transplanting: plants of 10 – 15 days old
  15. 15. Tamil Nadu: Traditional rice planting: close spacing of clumps and many seedlings (10)/clump
  16. 16. Transplanting young rice seedlings A 10-day rice seedling (SRI) Transplanting in rows (in clumps!)
  17. 17. Transplanting in rows of clumps - - Early transplanted rice, but NO SRI Transplanted rice in clumps of many (10) seedlings
  18. 18. Root and tiller development both plants seeded in the nursery on same day: on left: plant transplanted after 52 days; on right: a plant transplanted after 9 days and in wide spacing
  19. 19. Rice: close versus wide spacing; different phenotypes Line planting / high seed rate SRI: 1 plant/hill; wide spacing
  20. 20. Some fundamentals of (SRI) plant development • Every shoot / tiller has the capability to form a new tiller. • Given adequate time and space this leads to an exponential increase in the total number of tillers per plant (1, 2, 4, 8, 16, 32, 64, 128 ?, 256 ??). • Every tiller has the potential to develop a panicle. • Every tiller will develop at its base the roots to support it.
  21. 21. Changes in crop growth rate (CGR) for rice plants during vegetative stage grown under SRI and SMP practices. Closed and open circles represent SRI and SMP respectively (Thakur et al., 2010 ). 0 10 20 30 40 50 60 30-40 40-50 50-60 60-70 Period (Days after germination) CGR (g m -2 day -1 )
  22. 22. Nigeria: SRI on the left, or on the right ?
  23. 23. Andhra Pradesh: Rice roots and tillers Left: conventional clump; Right: SRI single plant
  24. 24. Root development under SRI/SCI (data courtesy A. Thakur) Plants / m2 Plants / hill Root dry weight (g) per hill Root dry weight (g) per m2 Conventional rainfed rice 150 3 4.2 206 Rainfed SRI 25 1 7.5 187 Rainfed SRI + suppl. Irrigation 25 1 10.2 254
  25. 25. Characteristics of SCI plants • Extended root systems + root activity • Increased efficiency in moisture and nutrient uptake from the soil (under non-flooded aerobic soils) • Increased efficiency in physiological functioning/ utilising solar radiation: increase in grain and straw production • Increased resilience to drought, pests, diseases, etc.
  26. 26. System of crop intensification: agronomy in a nutshell (courtesy Dr. Thakur) Rice systems Hills/m2 Plants/m2 Rice grain yield (t/ha) Conventional rainfed rice 50 150 2.9 d Rainfed SRI rice 25 25 4.4 c Rainfed SRI rice with suppl. irrigation from stored run-off water 25 25 6.2 a
  27. 27. SRI/SCI research: major results • Most crop varieties (local and improved) respond positively to SRI / SCI practices. • Drastically reduced (1/5th to 1/10th) seed rates increase the growth and physiological efficiency of individual plants and their disease tolerance . • Expanded root development per plant leads to an increased efficiency in moisture and nutrient uptake from the soil (Thakur et al., 2013) AND greater interaction between plant and soil biota (ranging from earthworms to fungi and bacteria: the soil bio-diversity.
  28. 28. SRI: an example of ecological intensification Optimise use of locally available resources: • Time and timing • Space (landscape) and spacing (plot/field) • Weather/climate: radiation/temperature/rainfal • Soil and organic materials • Organisms (plants/biota) above–below ground • Genotype x Environment (GxE) interactions • SOIL BIO-DIVERSITY
  29. 29. The Controversy
  30. 30. The empirical nature of SRI/SCI developed progressively on basis of field practices (bottom-up orientation), rather than scientific theory and/or fundamental research (top-down orientation)
  31. 31. SRI/SCI as a “silver bullet”?
  32. 32. The SRI / SCI package of practices as compared with conventional, best practices SRI/SCI agro-ecological: • very low seed rates • very young transplants: 8 to 15 days old • single transplants/hill • wide spacing: 20x20 to 50x50 cm • no flooding, moist soil • compost • 3 to 4 rounds rotary hoe Modern, conv. (irrigated): • high seed rates • young transplants: about 21days; or older • 3-5 transplants/hill • narrow spacing: 10x10 to 20x20 cm • continuous flooding • min. fertilizer + N topdr. • 2 rounds rotary hoe / herbicide
  33. 33. Agricultural sciences and policies: the “intensification” doctrine • Scaling up through mechanization • Increased farm size • Increased specialization • Largely top-down communication (extension services) • Cropping system intensification • “Improved”, short statured varieties: new seeds • Increased plant densities (high seed rates) • Mineral fertilizers (nitrogen in particular) • Irrigation / drainage • Regular crop protection treatments
  34. 34. Technology transfer vs learning process The “technology transfer” approach? The participatory approach: actor consultations,
  35. 35. Issues not, or poorly, addressed by the “intensification” doctrine • Soils and soil organic matter • Roots and root systems • Soil biota and micro-biodiversity • Interactions between : soils x roots x biota
  36. 36. Critical factors and dynamics in a “living” soil • Plants and roots / systems: specific root exudates as nutrition source for soil microbes • Soil organic matter: as energy/nutrition source for soil biota (from earthworms to microbes) • Soil micro-organisms: fungi and bacteria (micro- biodiversity); symbionts, decomposers, pathogens : a delicate, invisible equilibrium
  37. 37. The spacing x soil fertility interaction
  38. 38. Similar principles for other crops
  39. 39. Wheat-SWI: Kees Steendijk in Holland
  40. 40. Some intriguing questions • Why might farmers be tempted to over-seed? • How is it possible that farmers in both the North and the South are --even officially-- advised to use seed rates that are 5 to 10 times in excess of the optimum?
  41. 41. Conclusions and implications of SRI/SCI • Overall effects: • increased yields; • reduced costs (savings on seeds; on chemicals: mineral fertilizers / plant protection and on labor). SRI research exposes major knowledge gaps in Green revolution / conventional / modern agriculture. Conclusion: Conventional (science-steered) intensification has seriously overshot its target thereby even endangering sustainability !
  42. 42. Agricultural development dilemma Policy preferences • Concrete constraints/problems • Simple/easy solutions • Technology transfer - -> lineair process • Everything under control !? Farming realities • Diverse and variable communities and fields • Dynamic responses • Actor consultation - - > improvisation / adaptation • Flexible response to uncertainties

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