Implications ofTHE 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

More tillers and more than 400 grains per panicle

SRI is something quite remarkable and promisingBut it is a work in progress -- Qs > As• SRI appears ‘too good to be true’ --

but there is increasing evidence that it is ‘for real’

• SRI is being used successfully by – a growing number of farmers in – a growing number of countries

Q: WHAT CAN BE LEARNED FROM SRI? -- the main question today

SRI IS A METHODOLOGYrather than a

“TECHNOLOGY” -- not a fixed set of techniques

Different paradigm for rice growingwhich can be explained from the literature

SRI is basically a set of PRINCIPLES that are applied through

a set of PRACTICES that farmers are encouraged to

adapt to suit their local conditions

Basic idea of SRI is that RICE PLANTS DO BEST

(A) When their ROOTS can grow large and deep because they were

• transplanted carefully, i.e., without trauma, and with

• wide spacing between plants; and(B) When they can grow in SOIL that is:• well aerated with abundant and diverse• soil microbial populations

“Starting Points” for SRI• Transplant young seedlings, 8-15 days, quickly and very carefully

• Single plants per hill with wide spacing in a square pattern, 25x25 cm or wider

• No continuous flooding of field during the vegetative growth phase (AWD ok)

• Use rotating hoe early and often (2-4x)

• Application of compost is recommended

These practices produce very different PHENOTYPE from existing genotypes

OBSERVABLE BENEFITS• Average yields about 8 t/ha --

twice present world average of 3.8 t/ha

• Maximum yields can be twice this -- 15-16 t/ha, with some over 20 t/ha

• Water requirements reducible by 50%

• Increased factor productivity from land, labor, capital and water (> YIELD)

• Lower costs of production -- this is MOST IMPORTANT FOR FARMERS

LESS OR NO NEED FOR:• Changing varieties, though best yields

from high-yielding varieties and hybrids -- traditional varieties produce very well

• Chemical fertilizers -- these give very positive yield response with SRI, but best results are obtained from compost

• Agrochemicals – plants more resistant to pests and diseases with SRI methods

ADDITIONAL BENEFITS• Seeding rate reduced as much as 90%,

5-10 kg/ha gives more than 50-100 kg

• No lodging because of stronger roots

• Environmentally friendly production due to water saving, no/fewer chemicals

• More accessible to poor households because few capital requirements

DISADVANTAGES / COSTS• SRI is more labor-intensive, at least

initially -- but can become labor-saving• SRI requires greater knowledge/skill

from farmers to become better decision-makers and managers -- but this contri-butes to human resource development

• SRI requires good water control to get best results, making regular applications of smaller amounts of water -- this can be obtained through investments

SRI is COUNTERINTUITIVE• LESS BECOMES MORE -- by utilizing

the potentials and dynamics of biology• Smaller, younger seedlings will give

larger, more productive mature plants• Fewer plants per hill and per m2 can give

more yield • Half the water can give higher yield• Fewer or no external inputs are

associated with greater outputNew phenotypes from existing genotypes

These are remarkable claims• But they reflect experience on farms,

more than on experiment stations• I am not the originator of SRI -- just a

proponent for its being evaluated and used wherever it can be appropriate

• Many colleagues are now working on this system -- more than15 countries

• SRI is the due entirely to the work of Fr. Henri de Laulanié, S.J.(1920-1995)

SRI is most actively promoted by Association Tefy Saina

• NGO established by Fr. De Lalaunié and friends in 1990

• 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

• Tefy Saina joined CIIFAD in this effort, though not without our (my) skepticism

Initial Experience with SRI• Average yield of irrigated rice with standard

methods around Ranomafana National Park was about 2 t/ha at the time -- very low

• Previous work by NC State University had gotten average yield of 3 t/ha, max. of 5 t/ha

• CIIFAD would have been satisfied with an increase to 3-5 t/ha -- a doubling of yield

• Tefy Saina helped farmers average 8 t/ha over 1994-1999 period, some yields 16 t/ha

• Farmers in a French project improving small-scale irrigation on the high plateau had same results over same 5-year period

Spread beyond Madagascar

• Nanjing Agricultural University - 1999

• Agency for Agricultural Research and Development, Indonesia - 1999-2000

• Philippines, Cambodia, Sri Lanka, etc.

• China Hybrid Rice Center - 2000-2001

• International conference, Sanya, China, April 2001 -- 15 countries represented

Reports from Sanya ConferenceCOUNTRY No. of Data

Sets/Trials(No. of farmers)

Ave. SRIYield (t/ha)

ComparisonYield (t/ha)

Max. SRIYields (t/ha)

Bangladesh 4 On-farm (261)6 On-station

6.35.25-7.5

4.94.4-5.0

7.15.6-9.5

Cambodia 3 On-farm (427) 4.83.4-6.0

2.72.0-4.0

12.910.0-14.0

China 7 On-station w/hybrid varieties

12.49.7-15.8

10.910-11.8

13.510.5-17.5

Cuba 2 On-farm 9.158.8-9.5

6.25.8-6.6

NR

Gambia 1 On-farm (10)1 On-station

7.16.8-7.4

2.32.0-2.5

8.88.3-9.4

Indonesia 2 On-Farm5 On-station

7.46.2-8.4

5.04.1-6.7

9.07.0-10.3

Madagascar 11 On-farm(3,025)

3 On-station

7.24.2-10.35

2.61.5-3.6

13.95.6-21.0

Philippines 4 On-farm(47)

1 On-station

6.04.95-7.6

3.02.0-3.6

7.47.3-7.6

Sierra Leone 1 On-farm(160)

5.34.9-7.4

2.51.9-3.2

7.4

Sri Lanka 6 On-farm(275)

2 On-station

7.87.6-13.0

3.62.7-4.2

14.311.4-17.0

IDEAS FOR SUST. AGRIC. FROM SRI EXPERIENCE

Under appropriate mgmt conditions, TILLERING should be encouraged, not avoided -- provided that plants’ root systems are intact and functioning

In the literature, it is generally reported that there is an

inverse relationship between• the number of tillers/plant, and• the number of grains/panicleProfuse tillering is thought to be

wasteful and thus to be avoided -- “diminishing returns”

Comparison of highComparison of high--yield rice in tropical and yield rice in tropical and subtropical environments: I: Determinants of subtropical environments: I: Determinants of

grain and dry matter yieldsgrain and dry matter yieldsJ . Ying, S. J . Ying, S. PengPeng, Q. He, H. Yang, C. Yang, , Q. He, H. Yang, C. Yang,

R. M. R. M. VisperasVisperas, K. G. , K. G. Cassman Cassman Field Crops ResearchField Crops Research, 57 (1998), p. 72., 57 (1998), p. 72.

“…a “…a strongstrong compensation mechanism exists compensation mechanism exists between the two yield components between the two yield components [panicle number and panicle size]” with a [panicle number and panicle size]” with a ““strongstrong negative relationship between the negative relationship between the two components…” (emphasis added)two components…” (emphasis added)

The literature reflects conventional, suboptimal

growing conditions for rice -(a ‘closed system’ view)

• Under continuous flooding (hypoxic soil conditions), rice plant roots degenerate

• Rice is not an aquatic plant

AbstractAbstractNature and growth pattern of rice root systemNature and growth pattern of rice root systemunder submerged and unsaturated conditionsunder submerged and unsaturated conditionsS. S. KarKar, S. B. , S. B. VaradeVarade, T. K. , T. K. SubramanyamSubramanyam, and B. P. , and B. P. GhildyalGhildyal,,

I l I l RisoRiso (Italy), 1974, 23:2, 173-179 (Italy), 1974, 23:2, 173-179

Plants of the rice cultivar Plants of the rice cultivar TaichungTaichung (Native) were grown in pots of (Native) were grown in pots ofsandy loam under 2 water regimes in an attempt to identify criticalsandy loam under 2 water regimes in an attempt to identify criticalroot-growth phases. Observations on root number, length, volume,root-growth phases. Observations on root number, length, volume,and dry weight were made at the early and dry weight were made at the early tilleringtillering, active , active tilleringtillering,,maximum maximum tilleringtillering, and reproductive stages., and reproductive stages.

Rice root degeneration,Rice root degeneration, normally unique to submerged conditionsnormally unique to submerged conditions,,increased with advance in plant growth. At stage of flowering,increased with advance in plant growth. At stage of flowering,78%78% had degeneratedhad degenerated. . During the first phase under flooding, andDuring the first phase under flooding, and

throughout the growth period throughout the growth period under unsaturated conditions,under unsaturated conditions,roots rarely degeneratedroots rarely degenerated. (emphasis added). (emphasis added)

Physiology of Rice Roots

• Under continuously flooded conditions, most rice roots (about 3/4) remain in the top 6 cm of soil (Kirk and Solivas, 1997)

• Under continuously flooded conditions, rice plant roots form aerenchyma (air pockets), losing 30-40% of root cortex

• Under unflooded conditions, neither irrigated nor upland varieties form aerenchyma (Puard et al. 1989)

Root cross-sections ofRoot cross-sections ofupland (left) and irrigated (right) varietiesupland (left) and irrigated (right) varieties

ORSTOM researchORSTOM research ((PuardPuard et al. 1989) et al. 1989)

Soil aeration is important for (a) root survival/growth and (b) soil microbial abundance

and biodiversity• With SRI practices of plant, soil,

water and nutrient management, one gets very different root structure and performance

Evidence on Root System Development/Degeneration

Evaluated by ‘pull’ test of root resistance (O’Toole and Soemartono 1981)

• Three plants -- 3-week seedlings, 3/hill, close planting, continuous flooding -- averaged 28 kg/hill (Joelibarison 1998)

• Single SRI plants --12-day seedlings, 1/hill, 25x25 cm, aerated soil - averaged 53 kg/hill -- 5x more resistance/plant

Dry Matter Distribution of Roots in SRI and Conventionally-Grown Plants at

Heading Stage (CNRRI research: Tao et al. 2002)

Root dry weight (g)

Root Activity in SRI and Conventionally-Grown Rice

(Nanjing Agr. Univ. research: Wang et al. 2002)(Wuxianggeng 9 variety)

0

100

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N-n n-2 Heading Maturity

Development stage

Ox

yg

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ati

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/h.g

DW

)

W

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Conventional View of ROOTS

• Roots are “a waste” because they lower harvest index (HI)

• Roots are largely ignored in plant science research (cf. standard text on rice)

• We should change this view -- to more synergistic one

Importance of Structural (Qualitative) Analysis, not

just Quantitative View• Phyllochrons are a good

example of the value of going beyond quantitative analysis

• Also there are an example of parochialism in science when it is not truly international

Tillering in rice is regulated by a structural pattern of growth

• PHYLLOCHRONS apply to all gramineae species; more precise and illuminating than leaf age and degree-days

• Discovered by Katayama (1920s-30s), further developed by de Laulanié (1993)

• Under good growing conditions and if the root system is intact, the number of tillers per rice plant can exceed 100

PhyllochronPhyllochron is periodic interval of is periodic interval ofgrowth common to all growth common to all gramineaegramineae

In rice, a In rice, a phyllochronphyllochron is usually ~5-8 days long is usually ~5-8 days long In each period, the plant produces In each period, the plant produces one one or moreor morephytomersphytomers from its apical from its apical meristemmeristem

Each Each phytomerphytomer is a unit of a is a unit of a tillertiller, a , a leafleaf andanda roota root -- all growing synchronously -- all growing synchronously

PhyllochronsPhyllochrons represent represent biologicalbiological rather than rather thancalendar timecalendar time

They are either lengthened or shortened byThey are either lengthened or shortened byvarious factors that can various factors that can slow downslow down or or speed upspeed upthe plant’s the plant’s “biological clock”“biological clock”

What speeds up the biological clock?

(adapted from Nemoto et al. 1995)

Shorter phyllochrons Longer phyllochrons• Higher temperatures > cold temperatures• Wider spacing > crowding of roots/canopy• More illumination > shading of plants• Ample nutrients in soil > nutrient deficits• Soil penetrability > compaction of soil• Sufficient moisture > drought conditions• Sufficient oxygen > hypoxic soil conditions

Better growing conditions shorten the phyllochron

• This means that more phyllochrons of growth can be completed before plant switches from its vegetative growth phase to its reproductive phase

• More tillering means there is also more root development

This is what made it possible to go from 2 t/ha to 8 t/ha

• A synergistic relationship between root development and tillering

• With both together supporting increased grain filling in panicles

• Having massive root development,• 80% or more effective tillering,

• More filled grains, and • Higher grain weight

Positive benefits are seen from soil aeration during the

vegetative growth period

SRI capitalizes on the fact that the uptake of N is a

demand-led process

The The rate of uptake of N rate of uptake of N by rice roots by rice roots is is independent independent of theof the N concentrationN concentrationat the roots’ surface (Kirk and at the roots’ surface (Kirk and BouldinBouldin1991).1991).

[Whenever plants have sufficient N,] [Whenever plants have sufficient N,] rice roots ‘downrice roots ‘down--regulate’ their regulate’ their transport system for NHtransport system for NH4+4+ influx influx and/or ‘upand/or ‘up--regulate’ the efflux, regulate’ the efflux, thereby thereby exuding ammonium in excess exuding ammonium in excess of plant needs of plant needs ((Ladha Ladha et al. 1998).et al. 1998).

Paths for Increased Grain Yield in Relation to N Uptake, using QUEFTS

Analytical Model (Barison, 2002)

N Internal Efficiency

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12000

0 100 200 300

N uptake (kg/ha)

Gra

in y

ield

(kg/

ha)

SRI grain yield(kg/ha)

Conv. grain yield(kg/ha)

Rapid tillering and root growth

• SRI creates demand for nutrients -- due to the accelerating plant growth after the first 5-6 weeks

• But where does supply come from?

• Suggest that we need to consider biological processes and sources, not just nutrients “available” in soil

The contributions of soil microbial activity are more important than recognized

“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)

Biological Nitrogen Fixation?

• BNF can occur with all gramineae species, including rice (Döbereiner 1987, and others)

• In flooded paddies, BNF is limited to anaerobic processes; SRI provides aerobic conditions as well; BNF must be occurring

• Mixing aerobic and anaerobic soil conditions increases BNF (Magdoff and Bouldin 1970)

• Nitrogenase production is suppressed by the use of chemical fertilizers (van Berkum and Sloger 1983)

P SOLUBILIZATION?• 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

• “Microbiological weathering” is perhaps more important than are geochemical weathering processes?

• Biological weathering processes increase availability of other nutrients? S, Zn, Cu

MYCORRHIZAL Contributions?

• Fungi cannot grow in anaerobic soil so irrigated rice has forfeited the benefits of mycorrhizae for centuries

• Mycorrhizal fungi can increase volume of soil accessed by root 10 to 100x

• Plants with mycorrhizal associations can grow well with just a fraction of the P supply that “uninfected” plants need

Benefits from Rhizobia in rice now being explored

• Studied where rice and clover grown in rotation in Egypt, for many centuries

• These endophytic bacteria induce more efficient acquisition of N, P, K, Mg, Ca, Zn, etc. in rice (Yanni et al. 2001)

• Rhizobia increase yield and total protein quantity/ha, by producing auxins and other plant-growth promoting hormones -- however, no BNF demonstrable

ROOT EXUDATION• 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

• 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

Larger canopies and root systems increase exudation

and rhizodeposition• 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)

• Also 20% of plant N is transferred (Brimecombe et al. 2001)

• Roots and shoots are “two-way streets”• We should to apply what we learned in

biology classes to our agriculture

SRI Raises More Questions than It Gives ANSWERS

This is a PRACTICE-LED innovation• Scientists have a challenge/opportunity

to develop and “retrofit” explanations• Phenotypical changes are the starting

point -- these can surely be explained:– Greater root growth– Greater tillering – Less senescence of roots and canopy– Positive correlation: tillering x grain filling

Plant Physical Structure and Light Intensity Distribution

at Heading Stage (CNRRI Research: Tao et al. 2002)

Suggested Focuses for Explanation of SRI Effects

• Root developmentdifferent transplanting, wider spacing & soil aeration -- try to accelerate

• Soil microbial abundance and activityplant, soil, water & nutrient management, mixing aerobic / anaerobic conditions

THESE FOCUSES SURELY APPLY TO

OTHER PLANTS/CROPS• We hope that insights from SRI can

help to improve our agriculture in general, in ecological ways

• Need to keep a farming system view, concern with productivity > yield

• Most important, need to be ever more concerned with sustainability

THANK YOUMore information is available

on the SRI WEB PAGE:

http://ciifad.cornell.edu/sri/

including Sanya conference proceedings

E-MAIL ADDRESSES:

ciifad@cornell.edu

tefysaina@simicro.mg

ntu1@cornell.edu