From: Bruce Ewart <brucea@indo.net.id>To: Norman Uphoff <ntu1@cornell.edu>Subject: Many ThanksDate: Tue, 25 Feb 2003 07:42:57 +0700

Dear Norman, …Was in Lampung last week, and the crops planted for the

video are great. At 65 days, one crop will average about 65 tillers, and some are over 100 tillers, so the farmer and we are expecting a good crop. There is a good uptake of the system. In one village, there were 3 trials last year, and now 200 farmers are trying SRI. Some were so convinced by the trials that they are planting all SRI. The consensus now is that there is no more work required with SRI, and one farmer with 2 ha (very big crop here) considers that there is less work. He should know as he pays for all his labour. Thanks for keeping me in the loop. Regards,

Bruce Ewart [Indonesia director for ADRA]

Possible Soil Microbiological Explanations for High Yields

with the System of Rice Intensification (SRI)

Norman UphoffCIIFAD

More tillers and more than 400 grains per panicle

SRI ‘too good to be true’?(like the economist’s $100 bill)

• It goes against many concepts and beliefs of agronomists and economists: yield ceiling, soil depletion, tradeoffs, diminishing returns, etc.

• However, there is increasing evidence that SRI greatly raises rice productivity

• SRI is being used successfully by – a growing number of farmers in – a growing number of countries (16+)

• But SRI is a work in progress (Q’s > A’s)

OBSERVABLE BENEFITS• Average yields about 8 t/ha • Maximum yields can be twice this• Water required reduced by 50%• Lower costs of production• No need to change varieties (seeds)• Little or no need for fertilizers and

agrochemicals (greater resistance)• Increased factor productivity --

the most important consideration

SRI Data from Sri Lanka SRI Standard

• Yields (tons/ha) 8 4 +88%• Market price (Rs/ton) 1,500 1,300 +15%• Total cash cost (Rs/ha) 18,000 22,000 -18%• Gross returns (Rs/ha) 120,000 58,500 +74%• Net profit (Rs/ha) 102,000 36,500 +180%• Family labor earnings Increased with SRI• Water savings 40-50%

Data from Dr. Janaiah Aldas, formerly economist at IRRI, now at Indira Gandhi Development Studies Institute, Mumbai, based on visit to Sri Lanka and interviews with SRI farmers, October, 2002

DISADVANTAGES / COSTS

• SRI is more labor-intensive, at least initially -- but may 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, make regular applications of smaller amounts of water -- investment?

The basic idea of SRI is thatRICE PLANTS DO BEST when

• Plant ROOTS can grow large and deep having been transplanted carefully with seedlings experiencing little trauma, and with wider spacing between plants; and

• Rice plants are growing in SOIL that is kept well aerated, never continuously

saturated, with abundant and diverse populations of soil microbes that aid in plant nutrition

‘Starting Points’ for SRI:• Transplant young seedlings, 8-15 days

(2 leaves) -- 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)• Weeding with rotating hoe early (10 DAT)

and often -- 2 to 4 times

• Application of compost is recommended These are adapted to local situations

SRI practices produce a different RICE PHENOTYPE:

• Profuse TILLERING -- 30 to 50/plant, 80-100 possible, sometimes 100+

• Greater ROOT GROWTH -- 5-6x more resistance (kg/plant) for uprooting

• Larger PANICLES -- 150-250+ grains• Often higher GRAIN WEIGHT -- 5-10%• A POSITIVE CORRELATION between

tillers/plant and grains/panicle

SRI goes against LOGIC• LESS PRODUCES 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 as much water gives higher yield• Fewer or no external inputs are

associated with greater outputDifferent phenotypes from rice genomes

Plant Physical Structure and Light Intensity Distribution

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

These results more often come from farms than experiment stations

• But increasing number of scientists are working on SRI -- in China, Indonesia, India, Bangladesh, Cuba, etc.

• SRI is the due entirely to the work of Fr. Henri de Laulanié, S.J.(1920-1995), trained in agriculture at INA (1937-1939)

• He lived and worked with farmers in Madagascar, 1961-1995; SRI from 1983

• SRI being promoted by Malagasy NGO, Association Tefy Saina, assisted by CIIFAD

Data 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

Average Yields Impressive:Certain Cases Hard to Explain

• Indonesia -- West Timor (ADRA) • Yield with current methods -- 4.4 t/ha• Yield with SRI methods -- 11.7 t/ha Peru -- Pucallpa, jungle area• Previous yields -- 2 t/ha, with more labor• SRI yield -- 8 t/ha, with less labor + Ratoon crop = 70% of first crop -- 5.5 t/ha• Benin -- controlled trial: 1.6 vs. 7.5 t/ha

WHAT IS GOING ON?

SRI FIELD DAY REPORT, October 28, 2002, Agricultural TrainingInstitute, Department of Agriculture, at University of SouthernMindanao, Cotabato, Kabacan, Philippines

Production Analysis PSB Rc 72H PSB Rc 82 PSB Rc 18Plants=Hills/m2 16 16 16Panicles/hill 20 25.8 31Grains/panicle 191 155 159Grains/hill 3,825 4,822 4,921Yield/m2 1.16 1.25 1.2Yield (t/ha) 11.6 12.5 12.0

Economic Analysis Pesos/ha Pesos/ha Pesos/haInputs: seeds, org. fertiliz. 3,700 3,320 3,320Other expenses 5,830 5,830 5,830Harvesting, threshing 14,848 16,000 15,360Total Expenses/ha 24,378 25,150 24,510vs. Income @ 8 P/ha 93,800 100,000 96,000Net Income/ha 68,422 74,850 71,490 Rate of Return 280% 298% 292%

Comparison of high-yield rice in tropical andComparison of high-yield rice in tropical andsubtropical environments: I: Determinants ofsubtropical 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. CassmanCassmanField Crops ResearchField Crops Research, 57 (1998), p. 72., 57 (1998), p. 72.

“…a “…a strong compensation mechanismstrong compensation mechanism exists existsbetween the two yield componentsbetween the two yield components[panicle number and panicle size]” with a[panicle number and panicle size]” with a““strong negative relationshipstrong negative relationship between the between thetwo components…” (emphasis added)two components…” (emphasis added)

Effect of Young SeedlingsBetter Poorer

SS/20/3/NPK 3.00 2.04SS/ 8 /3/NPK 7.16 3.89SS/ 8 /1/NPK 8.13 4.36AS/ 8 /3/NPK 8.15 4.44AS/ 8 /3/Comp 6.86 3.61SS/ 8 /1/Comp 7.70 4.07AS/ 8 /1/NPK 8.77 5.00AS/ 8 /1/Comp 10.35 6.39

Critical Factor is Root Growth• 3/4 of rice roots in continuously flooded soil

remain in top 6 cm (Kirk and Solivas 1997)• 3/4 of rice roots in continuously flooded soil

degenerate by time of flowering (Kar 1974)• Air pockets (aerenchyma) form in roots of

rice plants when continuously flooded• These air pockets enable rice plants to

survive under submerged conditions• But submerged plants do not thrive --

lacking oxygen, their roots degenerate

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)

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,,

Il Il 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 degenerationRice root degeneration, normally unique to submerged conditions,, normally unique to submerged conditions,increased with advance in plant growth.increased with advance in plant growth. At stage of flowering, At stage of flowering,78% had degenerated78% had degenerated.. During the first phase under flooding,During the first phase under flooding,and throughout the growth period and throughout the growth period under unsaturated conditions,under unsaturated conditions,roots rarely degeneratedroots rarely degenerated.. (emphasis added) (emphasis added)

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

200

300

400

500

N-n n-2 Heading Maturity

Development stage

Oxy

gena

tion

abi

lity

of α -

NA

(ug/

h.gD

W)

WS

With young transplants and vigorous root growth,

• TILLERING is much greater• This can be explained in terms of

phyllochrons -- interval of plant growth found in all “grass” species

• Discovered by Japanese scientist Katayama in 1920s-30s

• Tillering pattern follows sequence of ‘Fibonacci series’ --1, 1, 2, 3, 5, 8, 13...

With best growing conditions, the phyllochrons are shorter

• So more periods of growth can be completed before the rice plant switches from

• vegetative growth phase• to reproductive phase• With more tillering, there is

also more root development

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).

Benefits are observed from soil aeration during the

vegetative growth period

Soil microbial activity is critical for plant nutrition

and SRI performance

“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)

Bacteria, funguses, protozoa, amoeba, actinomycetes, etc.

• Decompose organic matter, making nutrients available

• Acquire nutrients that are unavailable to plant roots

• Improve soil structure and health (water retention, pathogen control)

Biological Nitrogen Fixation

• Microorganisms -- particularly bacteria, both aerobic and anaerobic -- can fix nitrogen (N) from air into forms available to plant roots

• Research has shown that when aerobic soil and anaerobic soils are mixed, rather than having only aerobic soil or only anaerobic soil, BNF is greatly increased (Magdoff and Bouldin, 1970)

• BNF can occur with all gramineae -- not limited to leguminous species

• In flooded paddies, BNF is limited to anaerobic processes -- SRI provides aerobic conditions as well

• BNF must be occurring for the higher yields observed; not enough N measured in the soil

• Use of chemical fertilizers inhibits the production by the roots and microbes of nitrogenase, the enzyme needed for BNF (van Berkum and Sloger 1983)

AZOSPIRILLUM POPULATIONS, TILLERING AND RICE YIELDS ASSOCIATED WITH DIFFERENT CULTIVATION PRACTICES

AND NUTRIENT AMENDMENTSResults of trials at the Centre for Diffusion of Agricultural Intensification,

Beforona, Madagascar, 2000 (Raobelison, 2000)

Azospirillum in theCLAY SOIL (better) Rhizosphere

(103/ml)Roots

(103/mg)Tillers/plant

Yield(t/ha)

Traditional cultivation,no amendments

25 65 17 1.8

SRI cultivation, withno amendments

25 1,100 45 6.1

SRI cultivation, withNPK amendments

25 450 68 9.0

SRI cultivation, withcompost amendments

25 1,400 78 10.5

LOAM SOIL (poorer)SRI cultivation, withno amendments

25 75 32 2.1

SRI cultivation, withcompost amendments

25 2,000 47 6.6

This helps to solve puzzle• Why were many Madagascar farmers

putting their compost for SRI on their contra-saison crop -- not on rice crop?

• Both crops reportedly gave better yield• This makes no sense if LEACHING and

VOLATILIZATION are big problems, or if nutrients are ‘used up’ by plants

• It makes sense, however, for BNF

OPTIMUM RATES OF N FERTILIZER APPLICATION

Duration Early Medium Late100-110 days 111-120 days 121-135 days

Varieties 60 60 60Optimum NApplication 150-200 150 100Yield (t/ha) 5.36 5.64 5.76

From: J. K. Ladha, G. J. D. Kirk, J. Bennett, S. Peng, C. K.Reddy, P. M. Reddy and U. Singh (1998). Opportunities forincreased nitrogen-use efficiency from improved lowlandgermplasm. Field Crops Research, 56, 41-71.

Phosphorus Solubilization• Aerobic bacteria can acquire phosphorus

from unflooded soil for their own use• When the soil is flooded, these bacteria die

(lyse) and release their contents into the water that permeates the soil

• When the soil dries again, surviving bacteria begin their growth again

• Soluble P can increase by 185-1,900% by such ‘mining’ of the soil that increases nutrient supply (Turner & Haygarth, 2001)

Microbiological ‘Weathering’ of Soil?

• Soluble P can increase by 185-1,900% by microbiological ‘mining’ of the soil (Turner & Haygarth, 2001)

• Speculation that this process operates increase supply of other nutrients too

• Under ‘natural’ conditions, ‘depletion’ of soil is very rare occurrence -- due to microbiological processes

Mycorrhizal Associations• Mycorrhizal funguses ‘infect’ plant roots• They send out hyphae (filaments/threads)

in all directions and expand the volume of soil that the plant can extract nutrients from by 10-100 times

• Mycorrhizae are very good at harvesting phosphorus -- increased efficiency by 60x

• Mycorrhizae cannot grow in anaerobic soil conditions, so cannot benefit irrigated rice

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 demonstrated

Root Exudation• Plant stems & roots are ‘two-way’ streets• 30-60% of the energy (sugars, proteins)

made in the canopy is sent to the roots (Pinton et al., 2000)

• 20-40% of this energy supply is exuded by the roots into the soil -- feeding the bacteria, funguses, etc. in the root zone

• Root cells also die and provide energy to microbes through rhizodeposition

• Plants gain more than they lose from this

SRI Supports the Motto of Organic Farmers

• Don’t try to feed the plant --• Feed the soil -- and the soil

will feed the plant• Emphasis on symbiosis

between plants and soil microorganisms

SRI can be seen as an agronomic system for:

• Plant management -- young seedlings, careful transplanting, wide spacing

• Soil and water management -- leveling, ‘minimum of water’ for soil aeration

• Nutrient management -- increase SOM• Microorganism management -- result of

the above, promoted by root exudation

SRI Raises More Questionsthan we have answers for

• Many of the answers will be found in the growth and functioning of ROOTS, which grow better from:

• YOUNG SEEDLINGS, with• WIDE SPACING, and in• AERATED SOIL

• Answers will also be found in

SOIL MICROBIAL DYNAMICS -- in the abundance & diversity of soil microbes (bacteria, fungi)

Microbes grow better in: • SOIL not continuously flooded,• with more soil organic matter

Microbes benefit from exudation resulting from more root growth

.

THANK YOUMore information is available

on the SRI WEB PAGE:http://ciifad.cornell.edu/sri/

including Sanya conference proceedings,available on CD ROM discs

E-MAIL ADDRESSES:ciifad@cornell.edu

tefysaina@simicro.mgntu1@cornell.edu