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

1. Ecological Intensification
Lessons from SRI:
from “green revolution” to “agro-ecology”
Willem A. Stoop
December 2016

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. 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. 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. 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. Uttarkhand (India): terrased wheat fields
(light green); used as rice fields in wet season

7. Madagascar: (rice) field micro diversity
and smallholder adaptation

8. Burkina Faso: Crop adaptation to land types

9. Management of natural biological
processes: adaptation of practices
In response to diversity and variability in local:
Agro-ecological conditions
Socio-economic conditions

10. The “water” factor: irrigated and natural flooding (top),
rainfed uplands and rainfed lowlands in Mali and Burkina

11. System of rice (crop) intensification (SRI)
• Brief history
• A set of agronomic practices
• Rational for sustainable intensification

12. Liberia : a good SRI crop

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. Rice nurseries
Conventional rice nursery of old
(about 40 days) plants
SRI nursery at transplanting:
plants of 10 – 15 days old

15. Tamil Nadu: Traditional rice planting:
close spacing of clumps and many
seedlings (10)/clump

16. Transplanting young rice seedlings
A 10-day rice seedling (SRI)
Transplanting in rows (in
clumps!)

17. Transplanting in rows of clumps - -
Early transplanted rice, but NO
SRI
Transplanted rice in clumps of
many (10) seedlings

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. Rice: close versus wide spacing; different
phenotypes
Line planting / high seed rate SRI: 1 plant/hill; wide spacing

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. 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. Nigeria: SRI on the left, or on the right ?

23. Andhra Pradesh: Rice roots and tillers
Left: conventional clump; Right: SRI single plant

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. 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. 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. 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. 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. The Controversy

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. SRI/SCI as a “silver bullet”?

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. 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. Technology transfer vs learning process
The “technology transfer”
approach?
The participatory approach:
actor consultations,

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. 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. The spacing x soil fertility interaction

38. Similar principles for other crops

39. Wheat-SWI: Kees Steendijk in Holland

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. 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. 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