0405 What is Being Learned about SRI in China and Other Countries
What is Being Learned about the System of Rice Intensification (SRI) in China and Other Countries Norman Uphoff, CIIFAD CAWG-MOIST Seminar, Sept. 15, 2004
Message: For Centuries, Even Millennia, We Have Been ABUSING and MISTREATING the Rice Plant <ul><li>We have FLOODED it – drowning its roots </li></ul><ul><li>We have CROWDED it – inhibiting the growth potential of its canopy and roots </li></ul><ul><li>Now we apply various FERTILIZERS and chemical BIOCIDES affecting the soil biota which provide valuable services to plants: N fixation, P solubilization, protection against diseases and abiotic stresses, etc. </li></ul>
The System of Rice Intensification <ul><li>Evolved in Madagascar over 20 years by Fr. Henri de Laulanié, S.J. – working with farmers, observing, doing experiments, also having some luck in 1983-84 season </li></ul><ul><li>SRI is now spreading in countries around the world: positive results now seen in 21 </li></ul><ul><li>SRI is a set of principles and insights that when translated into certain practices can change the growing environment of rice to get healthier, more productive plants </li></ul>
Canopy of an individual rice plant grown under SRI conditions; usually this variety (Swarna) is ‘shy-tillering’ Andhra Pradesh, India, rabi season, 2003-04
Roots of a single rice plant (MTU 1071) grown at Agricultural Research Station Maruteru, AP, India, kharif 2003
SRI field in Sri Lanka -- yield of 13 t/ha with panicles having 400+ grains
CFA Camilo Cienfuegos, Cuba 14 t/ha -- Variety Los Palacios 9
SRI in Summary : <ul><li>A set of principles/methods that get more productive PHENOTYPES from any existing GENOTYPE of rice. </li></ul><ul><li>SRI changes the management of plants, soil, water, and nutrients to </li></ul><ul><li>(a) induce greater ROOT growth and </li></ul><ul><li>(b) nurture more abundant and diverse populations of SOIL BIOTA </li></ul>
Plant Physical Structure and Light Intensity Distribution at Heading Stage (CNRRI Research --Tao et al. 2002)
Dry Matter Accumulation between SRI and Control (CK) Practices (kg/ha) at Maturity (Zheng et al., SAAS, 2003)
Table 2. Different sizes of the leaf blade (cm) with SRI practices (Zheng et al., SAAS, 2003) 11.98 15.95 7.96 18.49 19.11 14.97 9.79 14.59 % Δ 0.20 8.86 0.16 9.00 0.30 9.29 0.14 8.18 +/- 1.67 55.56 2.01 48.67 1.57 62.03 1.43 56.07 CK 1.87 64.41 2.17 57.67 1.87 71.32 1.57 64.25 SRI Width Length Width Length Width Length Width Length Average Flag leaf 2 nd leaf 3 rd leaf Prac-tice
Figure 1. Change of leaf area index (LAI) during growth cycle (Zheng et al., 2003)
Different P aradigms of Production <ul><li>The GREEN REVOLUTION paradigm: </li></ul><ul><li>(a) Change the genetic potential of plants, and </li></ul><ul><li>(b) Increase the use of external inputs -- more water, fertilizer, insecticides, etc. </li></ul><ul><li>SRI changes various management practices for plants, soil, water and nutrients, which: </li></ul><ul><li>(A) Promote the growth of root systems , and </li></ul><ul><li>(B) Increase the abundance and diversity of </li></ul><ul><li>soil organisms , and also </li></ul><ul><li>(C ) Reduce water use and costs of production </li></ul>
Greatest Benefit Is not YIELD <ul><li>This can vary, often widely; for farmers, profitability is more important outcome </li></ul><ul><li>From society’s perspective, what is most important is factor productivity – kg of rice per land, labor, capital, and water ! </li></ul><ul><li>No question any longer of whether SRI methods give higher yields/productivity but rather how to explain these changes </li></ul><ul><li>For some things, we have evidence ; for others, strong hypotheses from literature </li></ul>
What Are the ‘Negatives’? <ul><li>Surprisingly few, but main one is labor intensity at least initially </li></ul><ul><li>This is receding as a constraint, mostly a problem for first few weeks or seasons </li></ul><ul><ul><li>Cambodian evaluation showed no increase (305 vs. 302 hrs/ha) -- and better timing </li></ul></ul><ul><ul><li>IWMI showed labor productivity higher by 50-62%, with just partial use of SRI method </li></ul></ul><ul><ul><li>Farmer innovation is helping to reduce labor requirements; more innovations will come </li></ul></ul>
Roller-marker devised by Lakshmana Reddy, East Godavari, AP, India, to save time in transplanting operations; his yield in 2003-04 rabi season was 16.2 t/ha paddy (dry weight)
4-row weeder designed by Gopal Swaminathan, Thanjavur, TN, India
What Are the ‘Negatives’? <ul><li>Less tractable is water control – although this can often be solved by infrastructure or organization – SRI makes changes pay </li></ul><ul><ul><li>Important for best results but may not be a barrier (R. Bunch report from Cambodia) </li></ul></ul><ul><li>Requirement of farmer learning and skill is a benefit as well as a cost </li></ul><ul><li>Disadoption has been reported as a problem only in Madagascar (e.g. Cambodia) </li></ul><ul><li>Nematodes can be a problem (e.g., Thailand) </li></ul>
Report from China, 2004 <ul><li>Several SRI introductions concurrently: </li></ul><ul><li>Dec. 1998 seminars at CAU and NAU ; first NAU field trials in 1999 (9.2-10.5 t/ha) </li></ul><ul><li>Article on in ILEIA journal (Dec. 1998) was read by CNRRI scientist, tried 1999 </li></ul><ul><li>Director of CNHRRDC attended IRRI seminar, Feb. 1999; and/or got SRI paper from June 2000 seminar at Cornell </li></ul><ul><li>3-S system was developed separately in 1991-96, field tested by 1999 by NEAU </li></ul>
Chinese Adaptations <ul><li>“ Triangular” system of planting – Liu Zhibin, Meishan, Sich. – got 16 t/ha and award from Prov. DOA </li></ul><ul><li>3-S system – uses 45 d seedlings because of cold temperatures; single seedlings planted with wide spacing (10,000 plants/mou), less water, more organic matter; but no active soil aeration -- use herbicides </li></ul>
Effects of Different Treatments within 3-S System +3.2% 10,323.4 25.7 79.8 141.0 357.0 6-03-04 +20.1% 11,967.5 25.9 81.5 145.0 391.0 5-21-04 -- 9,960.8 25.4 79.6 138.0 357.0 5-07-04 Panicles/m 2 TRANSPL. DATE +15.4% 11,080.9 24.03 89.5 120.2 21.7 1/hill +6.0% 10,174.2 22.77 88.0 132.5 19.6 2/hill -- 9,601.4 22.09 82.0 109.2 23.2 3/hill Panicles/ hill PLANTS/ HILL + 5.8% 11,544.7 25.2 77.0 133.7 445.1 43x14 cm -- 10,913.1 25.1 77.5 127.5 440.1 36x17 cm Change Yield (t/ha) 1000-gr weight (g) Seed set (%) Grains/ panicle Panicles/m 2 DENSITY: SPACING
Other Chinese Adaptations <ul><li>Plastic mulch with an upland version of SRI in Sichuan: 8 t/ha, less labor: gives weed control, conserves moisture, also better soil temperature; use plastic trays </li></ul><ul><li>Intercropping – potatoes, rape, or mushrooms are good alternating crops </li></ul><ul><li>In general: using 20-25d plants and herbicide for weed control, with single seedlings widely spaced , reduced water and more organic matter ; these methods give higher yields , often with less labor </li></ul>
Chinese Results, 2004 <ul><li>Heilongjiong Province: 10 t/ha in 2004 -- 44,000 ha under 3-S system </li></ul><ul><li>Guizhou Province: set high-altitude record in 2003 with SRI – 12.9 t/ha </li></ul><ul><li>Zhejiang Province, Tian Tai County: 10.8 t/ha in 2003; 11.5-12 t/ha in 2004 with 20 ha (300 mu), up to 13.5 t/ha </li></ul><ul><ul><li>Farmer experimentation is occurring </li></ul></ul>
SRI demonstration fields in Tien Tai, Zhejiang, China
Prof. Zhu Defeng, CNRRI, in field visit to SRI fields in Tian Tai, Zhejiang
Nie Fuqiu, Bu Tou village, Tian Tai, Zhejiang, describing his experiments within SRI system
Evaluation of SRI by CAU Xinsheng Village, Dongxi Township, Jianyang County, August 2004 <ul><li>2003 – 7 farmers used SRI (SAAS) </li></ul><ul><li>2004 – 398 farmers used SRI (65%) </li></ul><ul><li>2003 – SRI plot size average 0.07 mu </li></ul><ul><li>2004 – SRI plot size average 0.99 mu </li></ul><ul><li>86.6% of SRI farmers (65/75) said they would expand their SRI area next year or keep their whole rice area under SRI </li></ul>
Xinsheng Village, Dongxi Township [N = 75] (20% sample of all users) RICE YIELD (kg/mu) 2002 2003* 2004 Standard 403.73 297.88 375.77 Methods SRI -- 439.87 507.16 ----------------------------------------------------------- SRI Increase (%) +46.6% +34.8% * Drought year [Water saving/mu = 43.2%]
Other Results Reported, 2004 Sichuan Province – 60+ trials showed 10.5 t/ha average vs. 7.5 t/ha usual (double usual increase with hybrid rice) SAU – 11.75 t/ha; Leshan – 12.1 t/ha (10 300 mu); Meishan – 13.4 t/ha; SAAS field demonstration (observed) – 11.64 t/ha Hunan Province – 13.5 t/ha in field demonstration of CNHRRD (‘SRI’) Yunnan Province – 18 t/ha CNRRI trial 20.4 t/ha certified by Dept of S&T/SAU
Liu Zhibin, Meishan Inst. of Science & Technology, in raised-bed,no-till SRI field with certified yield of 13.4 t/ha
Biomass applied to SRI plots in Meishan, China
MEASURED DIFFERENCES IN GRAIN QUALITY Characteristic SRI (3 spacings) Conventional Diff. Paper by Prof. Ma Jun, Sichuan Agricultural University, presented at 10th conference on Theory and Practice for High-Quality, High-Yielding Rice in China, Haerbin, 8/2004 + 17.5 38.87 - 39.99 41.81 - 50.84 Head milled rice (%) + 16.1 41.54 - 51.46 53.58 - 54.41 Milled rice outturn (%) - 65.7 6.74 - 7.17 1.02 - 4.04 General chalkiness (%) - 30.7 39.89 - 41.07 23.62 - 32.47 Chalky kernels (%)
SRI Is not a ‘Niche Innovation’ <ul><li>(Dobermann, Agricultural Systems , 2004) </li></ul><ul><li>Nor is it ‘Voodoo Science’ [ Cold Fusion, UFOs] </li></ul><ul><li>(Cassman & Sinclair, ACSSA , 2004) </li></ul><ul><li>Sheehy et al. conclude in Field Crops Research (2004): </li></ul><ul><li>“ [SRI] has no major role in improving </li></ul><ul><li>rice production generally“ </li></ul><ul><li>This is not a valid conclusion, though presented as being ‘more scientific’ than our conclusions </li></ul><ul><li>SRI is ‘not finished yet’ – still evolving, still improving – can give seminar on explanations , already supported or justifiably hypothesized </li></ul>
The SRI Effect Is Not ‘Magic’ <ul><li>It should and can be explainable in terms of relationships that are consistent with what is known about rice scientifically and about rice’s interactions with its environment (G x E interaction) </li></ul><ul><li>A number of possible explanations have surfaced in recent years; not all need to be correct, since there are so many </li></ul><ul><li>We think some combination of the following can account for SRI performance </li></ul>
1 st Explanation? Above-Ground Environment <ul><li>Create ‘ the edge effect ’ for the whole field </li></ul><ul><li>Avoid edge effect only for measurement; promote it agronomically (triangle spacing) </li></ul><ul><li>Too-close spacing affects photosynthesis within canopy: measurements at AARD (Sukamandi, Indonesia) found that with normal spacing, lower leaves were being ‘subsidized’ by the upper leaves; wider spacing enables whole plant to contribute </li></ul>
2nd Explanation? Nitrogen Provision <ul><li>Rice yields increased 40-60% when same amount of N provided equally in both NO 3 and NH 4 forms vs. when all N is provided as NH 4 (Kronzucker et al., 1998) </li></ul><ul><li>BNF increases greatly with alternated aerobic/anaerobic conditions (Magdoff and Bouldin, Plant and Soil , 1970) </li></ul><ul><li>Contributions of protozoa to N supply </li></ul><ul><li>Also contributions from endophytes </li></ul>
3rd Explanation? Phosphorus Solubilization <ul><li>This nutrient is often limiting factor, but </li></ul><ul><li>Large amounts of P in soil (90-95%) are present in ‘unavailable’ form </li></ul><ul><li>Alternating wetting and drying of soil increased P in soil solution by 85-1900% compared with soils just wet or just dry (Turner and Haygarth, Nature , May 2001) </li></ul><ul><li>Aerobic bacteria acquire P from ‘unavailable’ sources during dry phase; during wet phase they lyse and release P into the soil solution </li></ul>
4 th Explanation? Mycorrhizal Fungi <ul><li>90+% of terrestrial plants derive benefits from and even depend on mycorrhizal associations (infections) </li></ul><ul><li>Mycorrhizal hyphae extend into soil and expand volume accessible to the plant by 10-100x , acquiring water, P and other nutrients ; they also provide protective/other services to plants </li></ul><ul><li>Flooded rice forgoes these benefits </li></ul>
5 th Explanation? Phytohormones <ul><li>Aerobic bacteria and fungi produce auxins, cytokinins, gibberellins , etc. in the rhizosphere </li></ul><ul><li>Huge literature has documented effects of microbially-produced phytohormones (e.g., Frankenberger and Arshad, 1995) </li></ul><ul><li>Root growth in SRI plants probably is not due just to physiological processes within the plants --stimulated by aerobic microorganisms? Roots are key to SRI </li></ul>
Single Cambodian rice plant transplanted at 10 days
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 Oxygenation Ability with SRI vs. Conventionally-Grown Rice Research done at Nanjing Agricultural University, Wuxianggeng 9 variety (Wang et al. 2002)
Table 13: Root Length Density (cm. cm -3 ) under SRI, ‘Modern’ (SRA) and Conventional Practice (from Barison, 2002) Results from replicated on-station trials 0.06 0.13 0.36 1.19 1.28 4.11 Conventional practice 0.07 0.15 0.31 0.55 0.85 3.24 SRA without fertilization 0.09 0.18 0.34 0.65 0.99 3.73 SRA with NPK and urea 0.20 0.25 0.32 0.57 0.71 3.33 SRI -- without compost 0.23 0.30 0.33 0.61 0.75 3.65 SRI -- with compost 40-50 30-40 20-30 10-20 5-10 0-5 Soil layers (cm) Treatments
Figure 8: Linear regression relationship between N uptake and grain yield for SRI and conventional methods, using QUEFTS modeling (from Barison, 2002) Results are from on-farm comparisons (N = 108)
Figure 9: Estimation of balanced N uptake for given a grain yield for rice plants with the SRI and conventional systems, using QUEFTS modeling (same for P and K) (Barison, 2002) Results are from on-farm comparisons (N = 108)
What Are Problems for SRI? <ul><li>Labor Requirements – initially more labor-intensive -- 25-50% </li></ul><ul><li>As farmers gain skill & experience, this is reduced, and SRI can even become labor-saving </li></ul><ul><li>GTZ evaluation of SRI in Cambodia: no difference in labor requirements (305 vs. 302 hrs/ha) – better timing </li></ul><ul><li>CEDAC evaluation of 120 farmers who have done SRI for 3 years: 55% said ‘easier’; only 18% said ‘more difficult’ </li></ul>
Adjustable-width weeder designed by Hari R., Moramanga, Madagascar (from IRRI design)
Labor-Saving Methods of Crop Establishment <ul><li>Tray methods – being developed in China, also in Cuba </li></ul><ul><li>Sowing/Thinning methods – started in India and Sri Lanka – broadcasting pregerminated seed (25 kg/ha) or young seedlings -- then ‘weed’ as usual , creating wide spacing with a square pattern (sacrifice seed for labor) </li></ul>
What Are Problems for SRI? <ul><li>2. Water Control – needed to get the best results with SRI methods </li></ul><ul><li>This constraint but can be reduced by investment in physical facilities or in organization and management </li></ul><ul><li>Most rice-growing countries will need to reduce the allocations of water for rice sector in coming yrs </li></ul><ul><li>SRI can help reduce water demand </li></ul>
Emerging Benefits of SRI? <ul><li>1. Resistance to Abiotic Stresses – climate becoming more ‘extreme’ and more unpredictable </li></ul><ul><li>Observed resistance to drought (Sri Lanka, several years) , hurricane (Sichuan – Sept. 2002) , typhoon (AP, India – Dec. 2003) , cold spell (AP, India – February 2004) </li></ul><ul><li>Resistance to lodging due to roots? </li></ul>
Two rice fields in Sri Lanka -- same variety, same irrigation system, and same drought : conventional methods (left), SRI (right)
Emerging Benefits of SRI? <ul><li>2. Resistance to Pests and Diseases – widely reported by farmers – probably reflecting the protective services of soil microorganisms </li></ul><ul><li>3. Higher Milling Outturn ~ 15%: SRI paddy raises outturn in India from 66 to 75%; in Cuba, from 60 to 68-71%; ‘adds to paddy yield’ </li></ul><ul><li>Fewer unfilled grains (less chaff) </li></ul><ul><li>Fewer broken grains (less shattering) </li></ul>
Emerging Benefits of SRI? <ul><li>4. Higher Nutritional Value of Rice? </li></ul><ul><li>SRI can be ‘organic rice’ that is free from agrochemical residues </li></ul><ul><li>Possibly SRI has higher nutritional quality in terms of micronutrients – needs to be evaluated scientifically </li></ul><ul><li>Larger root system gives higher grain weight and greater grain density also great nutrient density? </li></ul>
Emerging Benefits of SRI? <ul><li>5. Conservation of Rice Biodiversity ? </li></ul><ul><li>Highest SRI yields come with HYVs and hybrids (all SRI yields >15 t/ha) </li></ul><ul><li>But traditional/local varieties respond very well to SRI practice, can produce yields of 6-10 t/ha, and even more </li></ul><ul><li>Traditional rices receive higher price </li></ul><ul><li>Higher SRI yields make them popular </li></ul><ul><li>Get an ‘organic’ premium for export? </li></ul>
LESS CAN PRODUCE MORE <ul><li>by utilizing biological potentials & processes </li></ul><ul><li>Smaller, younger seedlings become larger, more productive mature plants </li></ul><ul><li>Fewer plants per hill and per m 2 will give higher yield if used with other SRI practices </li></ul><ul><li>Half as much water produces more rice because aerobic soil conditions are better </li></ul><ul><li>Greater output is possible with use of </li></ul><ul><li>fewer or even no external/chemical inputs </li></ul><ul><li>Changes in management practices give different phenotypes from rice genomes </li></ul>
SRI STILL RAISES MORE QUESTIONS THAN WE HAVE ANSWERS FOR <ul><li>This should please scientists – lot of interesting new work ahead </li></ul><ul><li>We are linking with researchers and practioners around the world </li></ul><ul><li>Two-pronged strategy: research and practice proceeding in tandem -- ‘walking on both legs’ as Mao advised </li></ul>
SRI Experience Could Help to Us to Improve 21 st Century Agriculture <ul><li>Nurturing of roots and soil biota is relevant for much of agriculture </li></ul><ul><li>We need an agriculture that is </li></ul><ul><ul><li>Less ‘thirsty’ -- better roots will help </li></ul></ul><ul><ul><li>Less dependent on fossil-fuel energy sources -- fertilizer, mechanization </li></ul></ul><ul><ul><li>Less dependent on agrochemicals -- for sake of soil & water quality, for health </li></ul></ul>
To raise world rice production by 60% by 2030, we will need to triple N fertilizer applications (Cassman et al., 1998) <ul><li>Who believes this is feasible ? </li></ul><ul><li>Who believes this is desirable ? </li></ul><ul><li>Who believes this is economically possible ? </li></ul><ul><li>Who believes this is environmentally sustainable ? SRI shows alternative way </li></ul>
SRI Data from Sri Lanka <ul><li> SRI Usual </li></ul><ul><li>Yields (tons/ha) 8.0 4.2 +88% </li></ul><ul><li>Market price (Rs/ton) 1,500 1,300 +15% </li></ul><ul><li>Total cash cost (Rs/ha) 18,000 22,000 -18% </li></ul><ul><li>Gross returns (Rs/ha) 120,000 58,500 +105% </li></ul><ul><li>Net profit (Rs/ha) 102,000 36,500 +180% </li></ul><ul><li>Family labor earnings Increased with SRI </li></ul><ul><li>Water savings ~ 40-50% </li></ul><ul><li>Data from Dr. Aldas Janaiah, IRRI agric. economist, 1999-2002; now at Indira Gandhi Development Research Institute in Mumbai; based on interviews conducted with 30 SRI farmers in Sri Lanka, October, 2002 </li></ul>
IWMI Data from Sri Lanka <ul><li>IWMI Evaluation (Namara, Weligamage, Barker 2003) </li></ul><ul><li>60 SRI and 60 non-SRI farmers randomly selected: </li></ul><ul><li>YIELD -- increased by 50% on average (not doing full SRI) </li></ul><ul><li>WATER PRODUCTIVITY -- increased by 90% </li></ul><ul><li>COST OF PRODUCTION (Rs./kg) -- lower by 111-209% with family labor, 17-27%at standard wage rate </li></ul><ul><li>LABOR PRODUCTIVITY (kg/hr) -- up 50% in yala (dry) season, up 62% in maha (wet) season </li></ul><ul><li>PROFITABILITY -- increased by 83-206%, depending on the wage assumed (family labor vs. paid labor) </li></ul><ul><li>RISK REDUCTION -- conventional farmers had net losses in 28% of seasons, SRI farmers in only 4% </li></ul>
SRI CONCEPTS CAN BE EXTENDED TO UPLAND PRODUCTION Results of trials (N=20) by Philippine NGO, Broader Initiatives for Negros Development, with Azucena local variety (4,000 m 2 area) -- using mulch as main innovation, not young plants
ROOT SYSTEM PROMOTION <ul><li>SRI is becoming referred to in India (AP) as ‘ the root revolution ’ -- key factor </li></ul><ul><li>Roots benefit from wider plant spacing, aerated soil, more soil organic matter --from both compost and root exudation </li></ul><ul><li>Roots are supported by more abundant and diversified populations of soil biota -- bacteria and viruses produce PGRs </li></ul><ul><li>Plants are two-way streets , coevolved w/ microorganisms, dependent on them </li></ul>
Root Research Reported by Dr. Ana Primavesi (1980) <ul><li>Shoot and root growth of maize (in g) grown in hydroponic solutions (14 days), with varying nutrient concentrations </li></ul><ul><li> Shoot Root </li></ul><ul><li>100% concentration 44 7 </li></ul><ul><li>200% concentration 34 7 </li></ul><ul><li>2% concentration 33 23 </li></ul><ul><li>2% concentration when 43 56 changed every other day </li></ul>
Contribution of SOIL MICROBIAL PROCESSES <ul><li>Microbial activity is known to be crucial factor in soil fertility </li></ul><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>
Bacteria, funguses, protozoa, amoeba, actinomycetes, etc. <ul><li>Decompose organic matter , making nutrients available </li></ul><ul><li>Acquire nutrients otherwise unavailable to plant roots </li></ul><ul><li>Improve soil structure and health -- water retention, soil aggregation, aeration, pathogen control, etc. </li></ul>
Effects of SRI vs. Conventional Practices Comparing Varietal and Soil Differences
Slides for presentation in the CIIFAD seminar series at Cornell University, September 15, 2004. These slides can be used or adapted, even translated, to assist SRI colleagues in explaining this methodology to others.
Signboard put up by the China National Rice Research Institute (bottom line) to announce demonstrations of SRI in Bu Tou village, Tian Tai county, Zhejiang province. In 2003, 30 mu (2 ha) of SRI rice were planted here, with a yield of 10.8 t/ha. In 2004, 300 mu (20 ha) were planted, with expected average yield of 11.5-12 t/ha, and some fields expected to yield 13.5 t/ha.
This was the message with which my presentations on SRI made during a three-week visit to China, August 22-Sept. 10, 2004, were started. This is a ‘bottom-line’ message summarizing what has been learned from SRI experience: the rice plant has much more potential for productivity than has been achieved because common practices constrain the expression of this potential.
This is a brief historical background. Fr. de Laulanie came to Madagascar from France in 1961 and started working on improvement of rice opportunities for the people there. It was not even tried anywhere outside China until 1999 (Nanjing Agricultural University), but it is now spreading rapidly. Vietnam is the 21 st country where SRI results have been demonstrated and documented. The 19 th and 20 th were Mozambique and Senegal.
This picture was provided by Dr. A. Satyanarayana, director of extension for the Indian state of Andhra Pradesh. In January 2004, I visited the field where this plant (and others) were being grown and saw how vigorous the plants were. This picture was taken shortly before harvest. Under usual growing conditions, the variety is productive and favored for its good grain quality, but it does not tiller like this without SRI practices.
Picture provided by Dr. P. V. Satyanarayana, the plant breeder who developed this very popular variety, which also responds very well to SRI practices.
Picture provided by Gamini Batuwitage, at the time Sr. Asst. Secretary of Agriculture, Sri Lanka, of SRI field that yielded 13 t/ha in 2000, the first year SRI was used in that country. Such performance got SRI started there..
Picture provided by Dr. Rena Perez of SRI field in 2002 at the cooperative where SRI got its start in Cuba. This field gave yields of about 6 t/ha before. This cooperative has expanded from 2 ha to 20 ha in SRI.
This is the most succinct statement of what SRI ‘is.’
This figure shows research findings from the China National Rice Research Institute, reported at the Sanya conference in April 2002 and published in the Proceedings. Two different rice varieties were used with SRI and conventional (CK) methods. The second responded more positively to the new methods in terms of leaf area and dry matter as measured at different elevations, but there was a very obvious difference in the phenotypes produced from the first variety's genome by changing cultivation methods from conventional to SRI. Both leaf area and dry matter were significantly increased by using SRI methods.
Graph showing results from research on SRI done by the Sichuan Academy of Agricultural Sciences. Same findings (except less dr matter in panicle) were found at the full heading stage.
Data from the Sichuan Academy of Agricultural Sciences comparing the length and width of leaves between SRI-grown and conventionally-grown rice, same variety, showing the difference in phenotype resulting from SRI practices.
Figure from Sichuan Academy of Agricultural Sciences research on SRI, comparing leaf area of SRI rice with conventional rice, same variety and otherwise same growing conditions.
SRI is often hard to accept because it does not depend on either of the two main strategies of the Green Revolution, not requiring any change in the rice variety used (genotype) or an increase in external inputs. The latter can be reduced.
Yield is a simple, usually dramatic number to talk about, but it is less important than profitability (at which SRI excels) and factor productivity (SRI is the only innovation to raise the productivity of all four simultaneously, something that most economists would regard as impossible, because they expect always tradeoffs). By utilizing existing biological processes and potentials, SRI can break out of the usual constraint of zero-sum relations and diminishing returns. This makes it hard for many to understand and accept at first, but over the last few years, we have gained a still-incomplete but nevertheless reasonable understanding of SRI processes from experience, from controlled experiments, and from the literature. SRI is not magic. It is fully understandable and explainable within what is already known in the realms of plant physiology and genetics and soil biology and ecology.
SRI started out being ‘labor-intensive,’ and this has become an unfortunate stereotype. SRI requires more labor to begin, when the farmer is getting acquainted with the methods and is learning them. But in Cambodia, several studies have shown it to neutral with regard to labor requirements, or even to reduce them once farmers have mastered the methods. In any case, SRI raises labor productivity so that farmers get higher returns from their labor, most important for small farmers who have to rely on their income from labor for their support. Perhaps most important, farmers are learning and inventing how to reduce the labor-intensity of SRI.
This was developed in 2003 by Mr. L. Reddy, to replace the use of strings and sticks to mark lines for planting, or the use of a wooden “rake” that could mark lines when pulled across the paddy in two directions. This implement, which can be built for any spacing desired, enables farmers, after it is pulled across the paddy in one direction, to plant SRI seedlings in a 25x250 cm square pattern. It saves as lot of labor time for transplanting because only one pass is needed across the field, and this is wider than a rake could be. Even wider ones have been built. Mr. Reddy is a very innovative and successful SRI farmer, with a superb yield last rabi season, measured and reported by the Department of Extension in Andhra Pradesh.
Mr. Swaminthan has built a weeder that by cultivating (removing weeds and aerating the soil) in four rows at a time can cut the time for ‘weeding’ in half. He has also devised an innovative system for crop establishment, suited to hot climates, called the Kadiramangalam system, described on our SRI home page (http://ciifad.cornell.edu/sri/)
Built by Luis Romero, one of the most successful SRI farmers in Cuba, to plant germinated seeds at 40x40 cm spacing. The seeds are put in the respective bins and dropped at the bins rotate. For his field, Luis found that 40x40 cm was too wide, because of weed problems. He has built one for 30x30 cm now. His neighbor built a seeder with 12 bins, four times as wide, that can be pulled by oxen to further save labor. The important thing to know is that farmers are working on their own ways to reduce SRI labor requirements because they see the benefits of wide spacing, aerated soil, etc.
The main constraint for getting best results is water control. Once everyone is satisfied that there is a great productivity increase possible with SRI, farmers and governments should become more willing to invest in the infrastructure needed to control water better. Governments in particular have an incentive to try to reduce the agricultural sectors’ demands for water given the growing scarcity of water with competing demands. The Roland Bunch report was from a village in Cambodia where the NGO ADRA is working. Farmers are very poor there, getting only 1 t/ha average yield from their rice, partly because they do not have good water control. To induce farmers to try SRI, ADRA promised it would compensate any who lost yield as a result of using SRI methods. Bunch reported in May 2003 that the 100 farmers who agreed to try SRI had averaged 2.5 t/ha and none had asked for any compensation, all being satisfied (many more than satisfied) with their yield. I am not sure how they got a 150% improvement (to be sure, from a low base) if they lacked water control, since soil aeration is a big part of the SRI methodology. Possibly even some improvement in water control had this large effect. This warrants more study. While SRI may take more investment up front in farmer training and motivation, it is a benefit for them and for society that they learn to be more experimental and innovative in their agricultural production. It has been reported from a number of countries that SRI is making farmers more interested in experimentation and innovation, so that their farming gets improved overall. Disadoption has been documented in Madagascar, but we are not seeing it as a problem elsewhere. Some disadoption may be likely for any innovation. But in Cambodia, one place where SRI has been well introduced, well explained, institutionally supported, and successful, the number of farmers using it has gone from 28 in 2000, to 400+ in 2001, to 2600+ in 2002, to 9100+ in 2003, to over 20,000 in 2004, with greater and greater interest and demand. Part of this is that the labor-intensity constraints have been solved. SRI is not a fixed technology but rather a set of ideas that get adapted to improve rice production. Disadoption is a possibility and sometimes a reality, but it is not inherent in SRI. One problem that is localized but serious is the emergence of harmful nematode populations (most nematodes are beneficial or neutral) in Thailand. This may account for why SRI results in Thailand and in Laos have not been as impressive as elsewhere, e.g., Cambodia and Myanmar. We need to be alert to such problems with SRI and to work on ways to overcome these as they arise. In Cuba, there is experimentation going on on different schedules of irrigation, so that a certain amount of flooding can control weeds. This might also control nematodes without sacrificing too much yield.
This presentation was made after a 3-week visit to China, to take stock of progress there with SRI methods. SRI got started in several different places in China, all about the same time. I gave seminars on SRI in December 1998 at China Agricultural University and Nanjing Agricultural University; NAU did trials the next summer and had good response, though this could be matched or exceeded by use of hybrid varieties and external inputs. That the SRI trials only required about half as much water, however, made their results interesting, since China needs to reduce the water consumed by agriculture (and rice). Dr. Zhu Defeng at the China National Rice Research Institute read an article by Tefy Saina published in the Dutch newsletter on low-external-input, sustainable agriculture in early 1999 and he started some trials. He is now the national coordinator for SRI activities. Prof. Yuan Longping, director of the China National Hybrid Rice Research and Development Center, either attended a seminar on SRI that I gave at IRRI (Los Banos) in February 1999 (which I have been told) or read about it in a paper of mine that I gave to IRRI scientist Henry Beachell who gave it to a Chinese colleague at the US company RiceTec who sent it to Prof. Yuan (what he reported in his presentation at Sanya in April 2002). Either way, evaluations of SRI began in 2000 at the CNHRDDC, and Prof. Yuan has become the most eminent proponent of SRI methods. Then, quite independently, Prof. Jin Xueyong at Northeast Agricultural University in Haerbin, Heilongjiong province, in the north of China, developed essentially the same system of practices during the early 1990s, and got them accepted by the provincial government by 1999.
Mr. Liu, who manages a hybrid seed multiplication farm for Prof. Yuan in Meishan, Sichuan province, understanding the concepts of SRI made an interesting and useful improvement on it, planting three plants per hill, instead of one, but staggering the hills and planting only half as many per sq. meter, so that the net increase in plant population was 50% while keeping wide spacing among plants because the three were planted in a triangular pattern with 7-10 cm spacing between them. In 2002, this method along with other SRI practices and use of hybrid seed got a 16 t/ha yield certified by the provincial Department of Agriculture, and given the award for highest yield in Sichuan. In China, this planting design and spacing are usually used now. 3-S, the system developed by Prof. Jin, operates under very cold conditions, where the soil in May-June is too cold for very young seedlings. So 45-day seedlings are used, planted singly, with wide spacing (equivalent of 25x25 cm), with reduction in water use and increase in compost use. Because of labor cost and scarcity, there is no effort to actively aerate the soil, and herbicides are used to control weeds. This method has spread to 44,000 ha in Heilongjiong province, with yields around 10 t/ha instead of usual 6 t/ha, and cost reductions. The following slides were provided by Prof. Jin.
Two fields of rice growth with normal methods and 3-S. The phenotypical differences are evident, much as seen with SRI.
Seedlings are started in heated greenhouses when there is still snow on the ground.
This is a 3-S seedling in upper left, and a 3-S plant in lower right.
Transplanting is done in rows (rectangular spacing among plants rather than square grid).
This spacing has been shown to be optimal. The aim is for 1 plant per hill, but if 2 are growing in the seedpot, they are planted together, not disturbing the roots.
No explanation needed.
Ditto. Prof. Jin has developed a very great appreciation for the importance of promoting vigorous root growth, as with SRI.
These differences are similar to what we see with SRI, showing that SRI like 3-S is tapping a potential that already exists in the rice genome.
This is a 3-S field planted with variety Kongyu 131. As seen two slides below, it is not necessarily the best variety with 3-S practices.
As with SRI, there is a measurable improvement in grain quality with these methods.
Data from Prof. Jin’s paper presented to the 10 th meeting on Theory and Practice of High-Quality, High-Yielding Rice in China, held at Haerbin, August 22-24, 2004. This shows a 28.5% yield advantage with 3-S methods under controlled conditions. It also shows a considerable difference in yield response of different varieties.
These data of Prof. Jin’s show the effects of wider spacing, and also that what they find to be the optimal planting date for 3-S.
Prof. Zhang Fusuo, dean of the college of Agricultural Resources and Environmental Sciences at China Agricultural University in Beijing, is working with SRI methods in Sichuan province, doing both lowland and upland SRI. His adaptation of SRI concept to upland conditions is very promising, getting 8 t/ha with labor saving, by using plastic mulch to control weeds. This also conserves water (which helps the plant) and gives better soil temperature (soil temperature is often too low in Sichuan). The use of plastic trays for starting, growing and transporting seedlings is also very beneficial. Researchers are looking at how SRI can best be complemented by other crops. Mr. Liu at Meishan started with potatoes and rape (a widely grown oilseed in Sichuan) in 2002 and found both crops benefiting from the association. Dr. Zhang is using rape and potatoes also. Dr. Zheng Jiaguo from the Sichuan Academy of Agricultural Sciences showed me in February 2004 how a SRI rice-mushroom rotation is catching on in Sichuan. More work should be done on how to utilize SRI rice in association with other crops, e.g., the rice-wheat rotational system, very common in China. That SRI rice avoids continuous flooding of paddies should improve soil conditions for the following wheat crop. At present, SRI adaptations in China are not using very young seedings or doing active soil aeration (weeding with rotating hoe), because of labor constraints, it is said. The other SRI practices are used and are giving good results, with labor saving. My hope is that once SRI is established, some farmers will experiment with these other two innovations, which we have seen from controlled factorial trials in Madagascar are the two most important means to raise yield and productivity.
The 3-S spread has been commented on before. The director of the Rice Research Institute in Guizhou, a southern province, said that last year, a SRI yield on a farmer’s field near Guiyang, the capital of the province, set a new record for high-altitude rice. In Zhejiang province, Dr. Zhu Defeng has a systematic program of SRI evaluation and demonstration in seven locations throughout the province. Data from Tian Tai country were given with the second slide. I visited these fields and farmers on August 27, 2004.
Prof. Zhu took me on this field visit and had obviously been following progress closely, with good rapport with farmers, who were very keen on SRI based on their results. They had calculated that with wider spacing and less irrigation, their main disease problem – sheath blight – had been reduced by 70%.
Nie is the farmer-demonstrator for the village, a kind of ‘master farmer’ in US extension terminology. He showed us the five experimental plots that he had set up, on his own initiative, within the SRI system, to evaluate raised beds, no-till cultivation, and every wide spacing (50x50 cm).
The Center for Integrated Agricultural University in the College of Humanities and Development at China Agricultural University did a socioeconomic evaluation of SRI in August 2004. The village selected had only 7 SRI users least year, but 398 this year. The size of SRI plot had also increased 14-fold, with a very positive attitude in the village toward SRI, for reasons seen on the next slide.
2003 was a drought year. The regular rice methods gave one-third lower yield; average yield that year with SRI methods (for the 7 farmers who tried them) was about a 4% increase, with SRI producing almost 50% more than regular methods. That has spurred the spread of SRI. In 2004, with more normal weather, SRI increased another 15%. The water saving calculated is also an incentive. But the survey of farmers found that LABOR SAVING with SRI methods was the most attractive advantage in their opinion.
The SAAS has comparison trials in over 100 locations this year. Over 60 had been harvested at the time I visited, and the average yield was 10.5 t/ha, a 3 t/ha improvement – results very similar to what were found last rabi season in Andhra Pradesh, India. Prof. Ma Jun of Sichuan Agricultural University got 11.75 t/ha in his controlled trials. In the mountain village of Leshan, where last year only about 20 mu were planted with SRI, with a yield of 12.2 t/ha, the lead farmer, whom I met in February 2003, told me that he expected 200 mu this season. In fact, there were 300 mu (20 ha) and the yield was 12.1 t/ha, the average yield holding up as the area expanded greatly. Z. B. Liu at Meishan got 13.4 t/ha on his best SRI plot, with raised beds and no-till. One of the SAAS comparison tests was visited on September 5, 2004, by a traveling workshop of some 80 rice specialists from all over the province. I observed the crop-cutting and also the measurement of moisture content in the grain to adjust reported grain yield to standard moisture levels. The result was 11.64 t/ha. I also visited a demonstration plot of the CNHRDDC’s super-hybrid rice outside Changsha, Hunan province, on September 8, 2004, which was projected to yield 13.5 t/ha. Prof. Yuan told me afterwards that this was being grown with ‘modified SRI’ methods, meaning that the triangular method of planting is used, and weeds are controlled by herbicide, not rotary hoe. The signboard informed everyone that the seedling age was 11 days. Prof. Zhu has been monitoring SRI trials in Yunnan province, and an officially registered crop-cutting shows an 18 t/ha yield on their best plot. Prof. Yang R. C., dean of the Fujian University of Agriculture and Forestry, has also been monitoring SRI plots in Yunnan and he told me they had reached 18 t/ha. Liu Z. B. showed me an official certificate of yield, signed by the Dept. of Science and Technology and by a professor of the Sichuan Agricultural University, for a yield of 20.4 t/ha in Yunnan, the record for China.
This is Liu Zhibin with a plot that was harvested just before my visit, with an official certificate for a yield of 13.4 t/ha. I was most interested in his experimentation with no-till methods and SRI.
Liu puts a lot of biomass onto his crop. Here we see leguminous cuttings added to the rice straw after harvest to keep soil organic matter high.
Prof. Ma Jun in his paper to the Haerbin conference included data on rice quality that he had collected. They showed SRI rice grains (from three different spacings within the SRI range) to be clearly superior in two major respects to conventionally-grown grains (two spacings). A reduction in chalkiness makes the rice more palatable. An increase in outturn is a ‘bonus’ on top of the higher yields of paddy (unmilled) rice that farmers get with SRI methods. We have seen this kind of improvement in outturn rates in Cuba, India and Sri Lanka, about 15%. More research on other aspects of SRI grain quality should be done, including nutritional content.
Despite (or maybe because of) the positive feedback coming on SRI from many countries, there has been this year a small spate of journal articles critiquing (dismissing) SRI. These are respected agronomists who, however, are making these claims with little or no systematic, empirical evidence to support them. The FCR article relied on data from three small trials done in China, not following any protocol that we would recognize as proper SRI methodology. The Hunan trials had so much N fertilizer applied that the SRI rice lodged, something rare (because SRI should be done with little external fertilization and preferably with organic fertilizers). The researchers ignored the 4-5 years of research results from leading rice research institutions in China (CNRRI, CNHRRDC, SAAS, NAU, CAU) in making these unfounded claims. Fortunately, a growing number of excellent scientists in China and elsewhere are engaging with SRI so that soon the accumulation of scientifically-acceptable data will make these dismissive claims irrelevant. The growing use of SRI by farmers will be the final refutation.
This begins a consideration of how and why we think SRI produces these remarkable results. By wider spacing, supporting greater root and canopy growth, we get ‘the edge effect’ for the whole field. This effect should be avoided when making estimates of yield, but should be welcomed agronomically.
This begins a consideration of how and why we think SRI produces these remarkable results. By wider spacing, supporting greater root and canopy growth, we get ‘the edge effect’ for the whole field. This effect should be avoided when making estimates of yield, but should be welcomed agronomically.
The alternate wetting and drying of paddy soil with SRI will increase the proportion of plant N that comes in the form of nitrate, which by itself, according to IRRI research, will enhance yield. It will also increase biological nitrogen fixation (BNF) according to research done at Cornell over 30 years ago. When soil is not kept flooded, the growth of aerobic bacteria on roots, and the grazing of these organisms by protozoa, will increase, especially with larger canopies and larger root systems putting out more exudation into the rhizosphere. Because protozoa have a lower C:N ratio than the bacteria they consume, they excrete the ‘excess’ N into the root zone. Published estimates of this N contribution to plant nutrition are that this can reach 20-40% of plant N, a source denied to rice plants with continuous flooding. Also, more and more research is being done on the contribution that endophytic bacteria make to plant nutrition and to other services (Dobbelaere et al., 2003).
These data were reported in Prof. Robert Randriamiharisoa's paper in the Sanya conference proceedings. They give the first direct evidence to support our thinking about the contribution of soil microbes to the super-yields achieved with SRI methods. The bacterium Azospirillum was studied as an &quot;indicator species&quot; presumably reflecting overall levels of microbial populations and activity in and around the plant roots. Somewhat surprisingly, there was no significant difference in Azospirillum populations in the rhizosphere. But there were huge differences in the counts of Azospirillum in the roots themselves according to soil types (clay vs. loam) and cultivation practices (traditional vs. SRI) and nutrient amendments (none vs. NPK vs. compost). NPK amendments with SRI produce very good results, a yield on clay soil five times higher than traditional methods with no amendments. But compost used with SRI gives a six times higher yield. The NPK increases Azospirillum (and other) populations, but most/much of the N that produced a 9 t/ha yield is coming from inorganic sources compared to the higher 10.5 t/ha yield with compost that depends entirely on organic N. On poorer soil, SRI methods do not have much effect, but when enriched with compost, even this poor soil can give a huge increase in production, attributable to the largest of the increases in microbial activity in the roots. At least, this is how we interpret these findings. Similar research should be repeated many times, with different soils, varieties and climates. We consider these findings significant because they mirror results we have seen in other carefully measured SRI results in Madagascar. Tragically, Prof. Randriamiharisoa, who initiated this work, passed away in August, 2004, so we will no longer have his acute intelligence and probing mind to advance these frontiers of knowledge.
The article by Turner and Haygarth opened up a new line of explanation for SRI results. Turner has visited Madagascar and is trying to get research started on how SRI methods may be mobilizing ‘recalcitrant’ P (esp. in inositol phosphate form) to get higher yields even when the measured ‘available’ P is very low (as it was around Ranomafana where we began our SRI work – 3-4 ppm).
It is well known that mycorrhizal fungi improve nutrition and protection against biotic and abiotic stresses in most terrestrial plants. Irrigated rice has been denied these benefits for many years. Research needs to be done to confirm this hypothesis, but it is only one of a dozen or more explanations for why SRI practices raise yield so much. Half of our hypotheses could be proved wrong, and yet the other half would suffice if they are established.
Research on phytohormones goes back 50 years or more but has not been integrated into agronomic analysis, being left in the domain of microbiology. We see such huge increases in root growth (and such variation in this) that it seems apparent that root growth (and plant vigor) is promoted (or not) by soil organisms producing auxins, cytokinins, etc. See next two pictures.
This picture was contributed from Cambodia by Koma Yang Saing (CEDAC). Viewers should try to imagine the very small single young seedling from which this massive plant grew.
These two rice plants are ‘twins,’ planted on the same day in the same nursery from the same seed bag. The one on the right was taken out at 9 days and transplanted into an SRI environment. The one on the left was kept in the flooded nursery until its 52 nd day, when it was taken out for transplanting (in Cuba, transplanting of commonly done between 50 and 55 DAP). The difference in root growth and tillering (5 vs. 42) is spectacular. We think this difference is at least in part attributable to the contributions of soil microorganisms producing phytohormones in the rhizosphere that benefit plant growth and performance.
This figure is from research reported by the China National Rice Research Institute to the Sanya conference and published in its proceedings. It shows how the roots of the same variety (two varieties shown) grow deeper into the soil with SRI methods compared to conventional ones (CK).
This figure from a report by Nanjing Agricultural University researchers to the Sanya conference, and reproduced from those proceedings, shows that the oxygenation ability of rice roots growing under SRI conditions are about double the ability, throughout the growth cycle, compared to the same variety grown under conventional conditions. At maturity, the SRI roots have still almost 3x the oxygenation ability of conventionally grown rice plants.
Barison did on-station trials at Beforona in Madagascar to compare many parameters of SRI vs. conventional rice plants. This shows the differences in root length density at different depths with different management practices. SRA stands for System de Riziculture Amelioree, system of rice improvement, promoted by government researchers using fertilizer, row planting, etc. – the ‘modern’ package in contrast with farmer practice.
In on-farm research, Barison analyzed the rice plants on 108 farms where farmers were using both SRI and conventional growing methods, so that there would be minimal influence of inter-farm or inter-farmer differences. Same varieties and same soils. The QUEFTS modeling exercise is quite standard in plant evaluation. The SRI plants had a very different capacity to take up N (and P and K) and to convert them into grain.
This is an analysis just for N (but the results were essentially the same for P and for K), showing how the plants are more internally efficient at converting N into grain. The conventional plants plateau at about 5 t/ha; the SRI plants plateau about 10 t/ha.
As noted above, labor requirements usually appear as the first and main constraint for SRI adoption. But we are finding that this is a transitory problem, though no less real for farmers in their season – and this can be a real barrier. We expect that with ongoing farmer innovation to reduce labor requirements through better methods and better implements, this will become a minor issue.
Some of the farmer innovations were shown already. Here is a weeder, taking an IRRI blueprint, made adjustable for row width by a local engineer in Madagascar.
The use of plastic trays in China is catching on as a labor-saving method. It will probably spread to other countries in the next few years. The most promising innovation is to avoid the need for establishing a nursery and for transplanting (two time-consuming operations) by broadcasting either germinated seed or young seedlings on muddy fields, and then after 10-12 days, when the plants have gotten established – taking the rotary weeder and ‘weeding’ the field as would be done normally for SRI, but actually thinning out the plant population radically, reducing it by about 80%, leaving plants only in small ‘hills’ 25x25 cm apart or at whatever spacing is desired. The seeding rate used by Mr. Ariyaratne Subesinghe in Sri Lanka, who uses germinated seed, is 25 kg/ha. He reduces the population down to an equivalent of 5 kg/ha. For the cost of 20 kg/ha of seed, he saves a lot of labor.
As noted already, this is probably the most important and objective constraint, though it is often ameliorable with some investment for infrastructure or organization. Once people understand that they can raise yield and productivity – and save water – by making such investments, we expect that irrigation systems will be improved. SRI can work with less than perfect water control, only the best results will not be achieved unless soil can be kept moist but not saturated (at least not saturated for any extended period of time).
This is becoming more evident as reports accumulate from different countries. Some systematic research should be undertaken on this.
This picture from Sri Lanka shows two fields having the same soil, climate and irrigation access, during a drought period. On the left, the rice grown with conventional practices, with continuous flooding from the time of transplanting, has a shallower root system that cannot withstand water stress. On the right, SRI rice receiving less water during its growth has deeper rooting, and thus it can continue to thrive during the drought. Farmers in Sri Lanka are coming to accept SRI in part because it reduces their risk of crop failure during drought.
Farmers in many countries have reported reduction in pests and diseases. Almost everywhere I visited in China, this was commented on. The 70% reduction in sheath blight in Tian Tai country, Zhejiang province, was noted above. It is not atypical. The improvements in grain quality are also widely observed and commented on. As seen above, Prof. Ma Jun from Sichuan Agricultural University, has given some precise data on this (slide 45).
This warrants research. It is usually the case that larger grains have less nutritional value, being mostly starch. However, with the larger root system and more densely packed grains (higher grain weight without larger size), we have reason to believe that there are nutritional improvements.
This is an unanicipated benefit. Young farmers in Sri Lanka are using SRI to preserve ‘traditional’ varieties that they like and value, but that have been sidelined by ‘improved’ varieties that give higher yields with higher inputs. Old varieties do poorly with such methods. But with SRI, they perform very well, and command a higher price in the market place because of preferred characteristics of taste, keeping quality, etc.
The Paraboowa Farmers Association has a dozen ‘wild rice’ varieties that it can grow for marketing or for export. The rice is grown ‘organically’ so can get a premium price in overseas markets. 17 tons have been exported to Italy already. The farmers want to preserve these varieties for future generations, and SRI enables them to do this.l
SRI defies usual logic – that to get more, you have to invest more. But “less” can produce “more,” for a number of different, but reinforcing reasons, well grounded in the scientific literature.
SRI is pointing toward some new thinking that could help to reshape agriculture in this new century, when we need to get away from ‘extensive’ production which is very costly in terms of energy, and which does not use our land resources (shrinking in per capital terms) to their fullest advantage. The 20 th Century practices will not disappear, but we expect that new production systems more fully based on biological knowledge and practice will emerge.
Ken Cassman and associates have figured that to raise rice production by 60% over the next 25 years, we will need to TRIPLE our use of N fertilizer. They say this to encourage research on how to use fertilizer more efficiently. But maybe we should be looking for ways to get off the “N treadmill,” where larger and larger amounts are needed to achieve smaller and smaller increments. SRI with its emphasis on root growth and functioning and on the symbiotic relationships between plants and soil biota could open some new opportunities.
What follow are slides used for other presentations that may be of interest as supplements. This graph was one of the first data sets that began laying a scientific foundation for SRI. Data were gathered from 76 farmers around Ambatovaky, a town on the western side of the peripheral zone around Ranomafana National Park in Madagascar, during the 1996-97 season. We had confidence in the field worker who collected the data, Simon Pierre, who had worked with Fr. de Laulanie before his death. The correlation between number of tillers per plant and number of grains per panicle was +.65, rather than the negative one expected from the literature. We have seen this positive relationship many times since this first analysis was done. With a large and functioning root system, rice plants become ‘open’ systems – rather than the ‘closed’ systems they are when their roots die back under flooded, hypoxic soil conditions – and thus they can support more tillering AND more grain filling. ‘Closed-system’ rice plants must made a tradeoff between phytosynthate and nutrient resources going into the tillers or into the grains.
A picture of an individual rice plant with 87 fertile tillers in the Cuban field shown in slide 8. They couldn’t get the whole plant into the picture.
Dr. Janaiah visited Sri Lanka the last week of October, 2002, and talked with 30 farmers in four villages who had been practicing SRI and who could give him detailed data. He had previously done such an evaluation for IRRI of the costs and benefits of adopting hybrid rice, having been on the IRRI staff in Los Banos from 1999 to 2002. He found SRI to be a much more profitable innovation for rice production than adoption of hybrids. We have found that SRI methods give the highest yields with hybrid varieties so there is not necessary contradiction or competition between the two. The SRI results reported from the Philippines, by the Agricultural Training Institute of the Department of Agriculture, from trials with three varieties at its Cotobato center in Mindanao (slide 20), calculated that the cost of production per hectare was 25,000 pesos, while the value of the rice yield with SRI was 96,000 pesos, a return of almost four times. Thus there are other evaluations of net profit from SRI that are even more favorable than Janaiah's calculation.
These summary data are taking from an evaluation reported in a paper to the ICID in November 2003; the full report is available now from IWMI as Research Report 75.
The ATI in Southern Mindanao, at Cotobato, tried SRI methods with three improved varieties in 2002 with these results. The average yield of 12 t/ha contrasts with IRRI’s first SRI yield at Los Banos of 1.44 t/ha. That poor result reinforced my thinking that differences in soil biota must be part of the SRI effect, as IRRI soils have had fertilizers and agrochemicals applied in abundance for 30 years, surely affecting the soil biotic populations. In Mindanao, such inhibition is less of a problem. The economic returns calculated are more important than the yield figure.
The NGO BIND, based in Bacalod City, Negros Occidental, adapted SRI concepts to upland (unirrigated) production, testing five spacings with four replications, in a 4,000 sq. meter area, relying only on rainfall. The fields were mulched with sesbania cuttings after the hills (planted with 3-4 seeds each ) had been thinned back at about 10 days after emergence to just one plant per hill. The mulch conserved moisture, suppressed weeds, and lowered soil temperature so that it was more hospitable to earthworms and other soil biota.
Dr. Primavesi did this experience in the late 1970s. It was reported in her 1980 book in Portuguese (she is Brazilian) and in a Spanish translation in 1984. But the work itself has been largely ignored. She had replicated trails growing maize seedlings for 14 days in solutions of different nutrient concentration. With 2% concentration, the shoot growth matched that for 200% concentration (100x more), but with roots growing to be three times larger. When the solution was changed every other day, replenishing the 2% level of nutrients, a ‘normal’ shoot growth was made possible by an 8-fold increase in root system. This suggests that plants need only very low levels of nutrients, but a constant supply for optimum growth.
Dr. DeDatta, one of the leading authorities on rice, acknowledged the importance of soil biota, but then in his text on rice hardly pays any more attention to them, unfortunately. This is typical of plant science in general. In DeDatta’s text, there is no even a single entry on roots in his index of over 16 pages (1100+ entries). There is one subentry referring to the rhizosphere, but that is to a single sentence saying that there is a rhizosphere, nothing more.
These are just the most obvious contributions. Our understanding of this netherworld is limited, though fortunately there are a growing number of microbiologists using very advanced modern techniques, such as DNA analysis, to map and track what is going on in the soil. The discussion that follows is can be viewed as introductory or superficial, or both.
This is a table that Fr. de Laulanie worked out based on the work of the Japanese scientist T. Katayama studying (discovering) phyllochrons as a regular interval of plant growth in gramineae species (rice, wheat, barley). For more on this, see Stoop et al. (2002) in AGRICULTURAL SYSTEMS.
This shows visually the pattern of tiller growth that is possible with an intact and functioning root system in rice plants – 84 tillers within 12 cycles of growth (12 phyllochrons).
These are results from replicated trials (each average is for 6 trials, within a randomly distributed Fischer bloc design) for a factorial-trial analysis of SRI looking among other things at the effect of young seedlings, on better and poorer soil, at Anjomakely, a village about 1200 m elevation in the central plateau of Madagascar . The synergistic effect of compost with aerated soil is seen in the bottom three lines. SS = submerged soil, AS = aerated soil; 20 = 20-day seedlings, 8 = 8-day seedlings; 3 = 3 per hill, 1 = 1 per hill; NPK = chemical fertilizer in recommended dose; Comp = compost, simply decomposed biomass, not farmyard manure. Compost with saturated soil does less well (7.7 t/ha) than NPK with aerated soil (8.77 t/ha), but compost with aerated soil does by far the best (10.35 t/ha) on better soil. The same relationship is seen on poorer soil (right-hand column).
Summary results from two sets of factorial trials in two different agroecological settings in 2000 and 2001 by honors students in the Faculty of Agriculture at the University of Antananarivo. The first setting was on the west coast of Madagascar, at an agricultural experiment center near Morondava, with a tropical climate, near sea level, and poor sandy soil. (This location was chosen because there are few pest or disease problems during that season which could affect plant performance.) The second was on the high plateau near the village of Anjomakely, 18 km south of Antananarivo, with a temperate climate, about 1200 m elevation, and better soils, comparing results on better clay soil and poorer loam soil. In 2000, Jean de Dieu Rajonarison did trials on 288 plots (2.5x2.5 m) at the Centre de Baobab, with sandy soil [ sable roux], evaluating the effects of five factors: variety – HYV  vs. traditional [riz rouge]; age of seedling [16-day vs. 8-day], seedlings per hill [3 vs. 1], water management [continuous flooding vs. water control, with deliberate aeration of the soil during the vegetative growth period], and nutrient amendments [none vs. NPK vs. compost]. The study was designed with spacing as a sixth factor [25x25 vs. 30x30cm], sok that there were 96 combinations (2x2x2x3x2x2), with three replications. But both spacings were within the SRI range, and the average yield distinguished by spacing [each N = 144] was identical, 3.18 t/ha. So the analysis deals with only five factors, having six replications for each average reported. Plots were randomly distributed according to a modified Fisher bloc design, except for water management, for which the plot with these two different treatments had to be separate to avoid effects of lateral seepage. In 2000, Andry Andriankaja did trials on 240 plots (2.5x2.5m) on a farmer’s fields near Anjomakely, using a traditional rice variety [ riz rouge], evaluating the effects of five factors: soil [clay vs. loam], age of seedling [20-day vs. 8-day – with colder temperatures, the onset of the 4 th phyllochron of growth is later than at Morondava], seedlings per hill [3 vs. 1], water management [continuous flooding vs. water control, with deliberate aeration of the soil during the vegetative growth period], and nutrient amendments [none vs. NPK vs. compost]. The reason why there are only 240 trials rather than 288 is that trials with no amendments were done only on the clay soil plots, not on the poorer loam soil plots, which were known to have low inherent fertility. This made for 40 combinations, with six replications. [The spacing factor as in the Morondava trials was not significant, with a difference of only 80 kg/ha for the two sets, each N = 120.] Again, all yields reported are averages for 6 replicated plots randomly distributed.