The document summarizes the System of Rice Intensification (SRI), a method of growing rice that can significantly increase yields. SRI involves transplanting young seedlings with wide spacing, minimal flooding of fields, and mechanical weeding. Trials in multiple countries found SRI can double average yields and maximize at over 20 tons/hectare using fewer external inputs. SRI is hypothesized to work by encouraging deeper, more extensive root growth and greater soil aeration, which enables more prolific tillering and larger rice plants.
The document summarizes the System of Rice Intensification (SRI) method of rice cultivation. SRI uses younger seedlings, wider spacing between plants, less flooding of fields, and other practices. It can significantly increase rice yields, often doubling average yields, while reducing water, seed, and other input needs. SRI goes against conventional agriculture wisdom but evidence shows it improves root and tiller growth, leading to higher productivity from existing rice varieties and genomes.
The document discusses factors that affect the phyllochron, or the time interval between the emergence of successive leaves, in rice plants. It reports on studies that found older seedlings and closer spacing resulted in longer phyllochron durations, negatively impacting tiller production and yield. Specifically, older seedlings experienced more root damage during transplanting, causing stress and slower growth rates, while closer spacing increased competition between plants for resources. Wider spacing and younger seedlings promoted higher tiller numbers and potential yields.
The document summarizes the System of Rice Intensification (SRI), a methodology developed in Madagascar to increase rice productivity through changes in plant management practices. SRI involves transplanting young seedlings singly and wider spaced, with minimal flooding. This induces greater root growth and soil biological activity, resulting in more tillers, larger plants and roots, higher yields, and other benefits. Field trials in many countries found SRI yields 30-100% higher than conventional methods with less inputs, water, and sometimes higher profits for farmers. The methodology is still evolving and many questions remain, but offers opportunities to improve rice and possibly other crop production systems.
Title: Mechanization and the System of Rice Intensification (SRI)
Presented by: Erika Styger
Presented at: Special Exhibit/Event on Rice Production at Agritechnica
Venue and Date: Hannover, Germany November 15, 2013
The document discusses the System of Rice Intensification (SRI), an alternative rice growing methodology developed in Madagascar that can potentially increase rice production while benefiting poor farmers and the environment. SRI involves transplanting young seedlings with wide spacing in unsaturated, aerated soil and can double or triple yields compared to conventional methods using fewer inputs like water, seeds, and fertilizer. Field trials in multiple countries found SRI increased average yields from 2-7 tons/hectare compared to conventional methods. SRI principles aim to help rice plants achieve their genetic yield potential through improved soil and plant management practices tailored to local conditions.
Low tunnel technology is used to grow cucurbitaceous vegetables out of season by protecting crops from frost and chilling. It involves constructing low tunnels using polyethylene sheets supported by bamboo poles. This traps heat inside and allows cultivation from December to February. Key benefits include higher yields, less water and fertilizer use, and overcoming challenges like cold temperatures and pests. Studies show growing cucumbers and other cucurbits under low tunnels can advance harvest by 30 days and increase profits compared to open field cultivation. Guidelines for successful use include proper orientation of tunnels, quality seeds, pest management, and timely irrigation.
The document summarizes the System of Rice Intensification (SRI) method of rice cultivation. SRI uses younger seedlings, wider spacing between plants, less flooding of fields, and other practices. It can significantly increase rice yields, often doubling average yields, while reducing water, seed, and other input needs. SRI goes against conventional agriculture wisdom but evidence shows it improves root and tiller growth, leading to higher productivity from existing rice varieties and genomes.
The document discusses factors that affect the phyllochron, or the time interval between the emergence of successive leaves, in rice plants. It reports on studies that found older seedlings and closer spacing resulted in longer phyllochron durations, negatively impacting tiller production and yield. Specifically, older seedlings experienced more root damage during transplanting, causing stress and slower growth rates, while closer spacing increased competition between plants for resources. Wider spacing and younger seedlings promoted higher tiller numbers and potential yields.
The document summarizes the System of Rice Intensification (SRI), a methodology developed in Madagascar to increase rice productivity through changes in plant management practices. SRI involves transplanting young seedlings singly and wider spaced, with minimal flooding. This induces greater root growth and soil biological activity, resulting in more tillers, larger plants and roots, higher yields, and other benefits. Field trials in many countries found SRI yields 30-100% higher than conventional methods with less inputs, water, and sometimes higher profits for farmers. The methodology is still evolving and many questions remain, but offers opportunities to improve rice and possibly other crop production systems.
Title: Mechanization and the System of Rice Intensification (SRI)
Presented by: Erika Styger
Presented at: Special Exhibit/Event on Rice Production at Agritechnica
Venue and Date: Hannover, Germany November 15, 2013
The document discusses the System of Rice Intensification (SRI), an alternative rice growing methodology developed in Madagascar that can potentially increase rice production while benefiting poor farmers and the environment. SRI involves transplanting young seedlings with wide spacing in unsaturated, aerated soil and can double or triple yields compared to conventional methods using fewer inputs like water, seeds, and fertilizer. Field trials in multiple countries found SRI increased average yields from 2-7 tons/hectare compared to conventional methods. SRI principles aim to help rice plants achieve their genetic yield potential through improved soil and plant management practices tailored to local conditions.
Low tunnel technology is used to grow cucurbitaceous vegetables out of season by protecting crops from frost and chilling. It involves constructing low tunnels using polyethylene sheets supported by bamboo poles. This traps heat inside and allows cultivation from December to February. Key benefits include higher yields, less water and fertilizer use, and overcoming challenges like cold temperatures and pests. Studies show growing cucumbers and other cucurbits under low tunnels can advance harvest by 30 days and increase profits compared to open field cultivation. Guidelines for successful use include proper orientation of tunnels, quality seeds, pest management, and timely irrigation.
This document discusses research advances in grafting and propagation techniques for vegetables. It begins by explaining what grafting is and its benefits, such as improved yield, stress tolerance, and production in non-traditional areas. Various grafting methods are described, and case studies of grafting for crops like tomato, cucumber, and cucurbit vegetables in India are provided. The history and current status of vegetable grafting are reviewed. The document also discusses specific benefits like increased resistance to biotic and abiotic stresses, improved growth, nutrient uptake and yield, and enhanced fruit quality.
This document discusses intercropping systems in fruit crop orchards. It describes how certain short-term fruit crops and vegetables can be grown as intercrops during the early stages of establishment of perennial fruit trees. Some examples given include papaya, peach, and guava as fruit crop intercrops in mango orchards. Vegetables like tomato, cauliflower, and beans are also mentioned as suitable intercrops in citrus and grape orchards. The document outlines principles for selecting intercrops and highlights benefits like increased productivity and income generation from intercropping in fruit crops.
This document discusses how high density planting (HDP) can help double farmer's income in India. It notes that traditionally, banana farms plant 2000-4000 plants per hectare, but with HDP, 4000-6000 plants can be accommodated per hectare. HDP increases banana yields from 40-60 tons per hectare traditionally to 80-120 tons per hectare. HDP reduces labor costs and allows for mechanization, improving farm efficiency and profits. While lack of dwarf varieties and disease incidence pose limitations, case studies show that HDP can increase net returns over traditional methods from Rs. 135,000 to Rs. 413,333 per hectare for banana farmers.
Grafting is a method employed to improve crop production. Grafting of vegetable seedlings is a unique horticultural technology practiced for many years in East Asia to overcome issues associated with intensive cultivation using limited arable land.The first grafted vegetable seedlings used were for Watermelon (Citrullus lanatus L.) plants grafted onto Lagenaria siceraria L. rootstock to overcome Fusarium wilt. Since then, the use of grafted solanaceous and cucurbitaceous seedlings has spread, with the practice mainly used in Asia, Europe, and North America. The expansion of grafting is likely due to its ability to provide tolerance to biotic stress, such as soilborne pathogens, and to abiotic stresses, such as cold, salinity, drought, and heavy metal toxicity, due to the resistance found in the rootstock. Many aspects related to rootstock/scion interactions are poorly understood, which can cause loss of fruit quality, reduced production, shorter postharvest time, and, most commonly, incompatibility between rootstock and scion. The rootstock and scion cultivars must be chosen with care to avoid loss.
Growing Everbearing Strawberries as Annuals in Alaska; Gardening Guidebook for Fairbanks, Alaska www.scribd.com/doc/239851313 - Tanana District Master Gardeners, University of Alaska, For more information, Please see Organic Edible Schoolyards & Gardening with Children www.scribd.com/doc/239851214 - Double Food Production from your School Garden with Organic Tech www.scribd.com/doc/239851079 - Free School Gardening Art Posters www.scribd.com/doc/239851159 - Increase Food Production with Companion Planting in your School Garden www.scribd.com/doc/239851159 - Healthy Foods Dramatically Improves Student Academic Success www.scribd.com/doc/239851348 - City Chickens for your Organic School Garden www.scribd.com/doc/239850440 - Huerto EcolĂłgico, TecnologĂas Sostenibles, Agricultura Organica www.scribd.com/doc/239850233 - Simple Square Foot Gardening for Schools, Teacher Guide www.scribd.com/doc/23985111 ~
This document discusses tomato grafting techniques. It defines grafting as joining parts of two plants so they unite and grow as a single plant. Benefits of grafting tomatoes include resistance to soil-borne diseases and nematodes from rootstocks, as well as desirable traits from scion cultivars. Methods covered include tubing, tongue, and cleft grafting. Healing grafts is critical and involves high humidity, warm temperatures, and initial darkness. Rootstocks discussed increase disease resistance or vigor.
Triple S, a new approach to sweet potato planting material conservation involving storage in sand and sprouting, was tested in Ethiopia. In areas with 3-5 month dry seasons, Triple S produced higher quality and greater quantities of planting material with less weevil and virus damage compared to traditional methods. For areas with 7-9 month dry seasons, medium sized roots stored longest using Triple S, sprouting over 8 months. Triple S shows promise for addressing planting material shortages across Ethiopia's varied dry season lengths.
Intercultural practices ,Cultural practices in AgreculturalSamraz Qasim
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This document discusses various intercultural practices for crops including weeding, mulching, earthing up, thinning, and gap filling. Weeding involves removing weeds to reduce competition for crops. Mulching involves covering the soil to conserve moisture by reducing evaporation. Earthing up lifts soil around crop bases to improve anchorage and prevent lodging. Thinning removes excess seedlings to avoid overcrowding. Gap filling replants areas where seedlings did not establish to optimize plant population. The goal of thinning and gap filling is to ensure an optimum plant density. Various tools are used for different intercultural operations.
Rejuvenation of Old/senile orchards-A success storyParshant Bakshi
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The document discusses rejuvenation of old or senile orchards as a way to restore their productive capacity. It describes how orchards become uneconomic over time due to issues like wild shrub growth, overcrowding of trees, damage from weather/pests, and use of inferior varieties. Rejuvenation involves pruning trees to renew growth from latent buds and improve the root to shoot ratio. Examples provided include heading back mango and guava trees to develop a new canopy in 2 years and increase yields by 4-5 times.
This document provides a summary of the 2010 PEST MANAGEMENT UPDATE Forages, Pastures, and Invasive Plants from the University of Wisconsin-Madison. It discusses new herbicide labels for use in pastures and forages, techniques for controlling winter annual weeds in alfalfa, establishing legumes after herbicide application, and managing herbicide persistence in manure to avoid impacting sensitive crops. The document also provides resources on identifying and managing invasive plant species according to Wisconsin's new invasive species rule.
This document discusses weed management in alfalfa. Weeds can reduce alfalfa establishment, yield, and forage quality. The critical period for weed removal is 3-5 weeks after planting. Herbicides like Pursuit and Raptor can be used during establishment with some potential yield loss. Roundup Ready alfalfa allows post-emergence glyphosate applications with more flexible timing but has higher seed and technology costs. Weed management is important to secure stand establishment and provide high quality forage, especially in the first cutting. Management options depend on weed species, density, and field conditions.
Cereal rye is an excellent winter cover crop that rapidly provides ground cover to prevent soil erosion. It has deep roots that help prevent soil compaction and scavenge nutrients from the soil profile. Rye also helps control weeds when used as a mulch in no-till systems. Rye is easy to grow and establishes well with seeding rates of 60 to 200 pounds per acre. It can be killed with mowing or herbicides to allow no-till planting of other crops while providing weed suppression for about 30 days as a surface mulch.
This document provides information on rice cultivation techniques and varieties in Pakistan. It discusses the botanical classification of rice, the structure of rice plants and seeds, growth stages of rice from germination to ripening, and factors that influence rice yield such as soil selection, variety selection, fertilizer use, and pest management. It also outlines different rice varieties grown in Pakistan's provinces and the soil and climate conditions suitable for rice cultivation. Methods of sowing rice nurseries and transplanting rice are described. Pests that affect rice such as stem borers and plant hoppers are also mentioned.
This document discusses various propagation techniques for small cardamom. It describes seed propagation methods including seed collection, treatment, sowing, and nursery practices. Vegetative propagation through division of rhizomes is also covered. The document outlines micropropagation stages from selection of explants to rooting and acclimatization. Micropropagation provides a means to rapidly multiply planting material through tissue culture. Various growth media and plant growth regulators are used to induce shoot formation, elongation, and rooting.
Seed orchard establishment and management shambhu tiwarisahl_2fast
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This document provides an overview of seed orchards, including their establishment, management, and purpose. Seed orchards are stands established to mass produce genetically superior seeds. The first documented pine seed orchard was established in Sweden in 1949, though the concept was applied earlier for other species. Seed orchards can be either seedling or clonal, and are carefully located, designed, established, and managed to promote outcrossing pollination and maximize seed production. Key activities include site preparation, genetic rouging, thinning, pruning, and flower induction. The overall goal of seed orchards is to efficiently produce high quality forest tree seeds to improve forests through subsequent plantings.
Vegetable grafting involves grafting a scion vegetable plant onto a rootstock plant to improve traits like disease resistance, abiotic stress tolerance, yield and quality. The document discusses the history of vegetable grafting, benefits like resistance to soilborne diseases and tolerance to stresses. It also describes different grafting methods like cleft grafting and tube grafting used for various rootstock-scion combinations in vegetables like tomato, eggplant, cucumber and watermelon. Automated grafting has increased grafting efficiency and reduced costs compared to manual grafting. Some examples of vegetable grafting experiments conducted in India are also provided.
This chapter discusses factors for successful jatropha cultivation for oil production, including climate, soil, propagation, and crop management practices. It describes optimal climate conditions as tropical or subtropical, with rainfall between 1000-1500mm annually. Soil should be well-draining sand or loam at least 45cm deep. Propagation can be from seed or cuttings, with seedlings having higher survival rates. Intercropping is common during early establishment, and pruning, weeding, and pollinator presence help maximize yields once mature.
- The System of Rice Intensification (SRI) is an alternative methodology for growing rice that can significantly increase yields using fewer external inputs. It involves transplanting young seedlings with wide spacing, maintaining moist soil conditions, and mechanical weeding.
- SRI has led to increased yields of 8-16 tons/hectare in various countries, compared to average worldwide yields of 3.8 tons/hectare, through profuse tillering, greater root growth, larger panicles, and less water requirement. Additional benefits include lower costs, higher profits, and less need for fertilizers and agrochemicals.
- While counterintuitive, SRI principles take advantage of plant biology and dynamics
Presenter: Norman Uphoff
The Cornell Agroforestry Working Group/ The Management of Organic Inputs in Soils of the Tropics Group (CAWG/MOIST) Seminar Series 2003, USA
This document discusses research advances in grafting and propagation techniques for vegetables. It begins by explaining what grafting is and its benefits, such as improved yield, stress tolerance, and production in non-traditional areas. Various grafting methods are described, and case studies of grafting for crops like tomato, cucumber, and cucurbit vegetables in India are provided. The history and current status of vegetable grafting are reviewed. The document also discusses specific benefits like increased resistance to biotic and abiotic stresses, improved growth, nutrient uptake and yield, and enhanced fruit quality.
This document discusses intercropping systems in fruit crop orchards. It describes how certain short-term fruit crops and vegetables can be grown as intercrops during the early stages of establishment of perennial fruit trees. Some examples given include papaya, peach, and guava as fruit crop intercrops in mango orchards. Vegetables like tomato, cauliflower, and beans are also mentioned as suitable intercrops in citrus and grape orchards. The document outlines principles for selecting intercrops and highlights benefits like increased productivity and income generation from intercropping in fruit crops.
This document discusses how high density planting (HDP) can help double farmer's income in India. It notes that traditionally, banana farms plant 2000-4000 plants per hectare, but with HDP, 4000-6000 plants can be accommodated per hectare. HDP increases banana yields from 40-60 tons per hectare traditionally to 80-120 tons per hectare. HDP reduces labor costs and allows for mechanization, improving farm efficiency and profits. While lack of dwarf varieties and disease incidence pose limitations, case studies show that HDP can increase net returns over traditional methods from Rs. 135,000 to Rs. 413,333 per hectare for banana farmers.
Grafting is a method employed to improve crop production. Grafting of vegetable seedlings is a unique horticultural technology practiced for many years in East Asia to overcome issues associated with intensive cultivation using limited arable land.The first grafted vegetable seedlings used were for Watermelon (Citrullus lanatus L.) plants grafted onto Lagenaria siceraria L. rootstock to overcome Fusarium wilt. Since then, the use of grafted solanaceous and cucurbitaceous seedlings has spread, with the practice mainly used in Asia, Europe, and North America. The expansion of grafting is likely due to its ability to provide tolerance to biotic stress, such as soilborne pathogens, and to abiotic stresses, such as cold, salinity, drought, and heavy metal toxicity, due to the resistance found in the rootstock. Many aspects related to rootstock/scion interactions are poorly understood, which can cause loss of fruit quality, reduced production, shorter postharvest time, and, most commonly, incompatibility between rootstock and scion. The rootstock and scion cultivars must be chosen with care to avoid loss.
Growing Everbearing Strawberries as Annuals in Alaska; Gardening Guidebook for Fairbanks, Alaska www.scribd.com/doc/239851313 - Tanana District Master Gardeners, University of Alaska, For more information, Please see Organic Edible Schoolyards & Gardening with Children www.scribd.com/doc/239851214 - Double Food Production from your School Garden with Organic Tech www.scribd.com/doc/239851079 - Free School Gardening Art Posters www.scribd.com/doc/239851159 - Increase Food Production with Companion Planting in your School Garden www.scribd.com/doc/239851159 - Healthy Foods Dramatically Improves Student Academic Success www.scribd.com/doc/239851348 - City Chickens for your Organic School Garden www.scribd.com/doc/239850440 - Huerto EcolĂłgico, TecnologĂas Sostenibles, Agricultura Organica www.scribd.com/doc/239850233 - Simple Square Foot Gardening for Schools, Teacher Guide www.scribd.com/doc/23985111 ~
This document discusses tomato grafting techniques. It defines grafting as joining parts of two plants so they unite and grow as a single plant. Benefits of grafting tomatoes include resistance to soil-borne diseases and nematodes from rootstocks, as well as desirable traits from scion cultivars. Methods covered include tubing, tongue, and cleft grafting. Healing grafts is critical and involves high humidity, warm temperatures, and initial darkness. Rootstocks discussed increase disease resistance or vigor.
Triple S, a new approach to sweet potato planting material conservation involving storage in sand and sprouting, was tested in Ethiopia. In areas with 3-5 month dry seasons, Triple S produced higher quality and greater quantities of planting material with less weevil and virus damage compared to traditional methods. For areas with 7-9 month dry seasons, medium sized roots stored longest using Triple S, sprouting over 8 months. Triple S shows promise for addressing planting material shortages across Ethiopia's varied dry season lengths.
Intercultural practices ,Cultural practices in AgreculturalSamraz Qasim
Â
This document discusses various intercultural practices for crops including weeding, mulching, earthing up, thinning, and gap filling. Weeding involves removing weeds to reduce competition for crops. Mulching involves covering the soil to conserve moisture by reducing evaporation. Earthing up lifts soil around crop bases to improve anchorage and prevent lodging. Thinning removes excess seedlings to avoid overcrowding. Gap filling replants areas where seedlings did not establish to optimize plant population. The goal of thinning and gap filling is to ensure an optimum plant density. Various tools are used for different intercultural operations.
Rejuvenation of Old/senile orchards-A success storyParshant Bakshi
Â
The document discusses rejuvenation of old or senile orchards as a way to restore their productive capacity. It describes how orchards become uneconomic over time due to issues like wild shrub growth, overcrowding of trees, damage from weather/pests, and use of inferior varieties. Rejuvenation involves pruning trees to renew growth from latent buds and improve the root to shoot ratio. Examples provided include heading back mango and guava trees to develop a new canopy in 2 years and increase yields by 4-5 times.
This document provides a summary of the 2010 PEST MANAGEMENT UPDATE Forages, Pastures, and Invasive Plants from the University of Wisconsin-Madison. It discusses new herbicide labels for use in pastures and forages, techniques for controlling winter annual weeds in alfalfa, establishing legumes after herbicide application, and managing herbicide persistence in manure to avoid impacting sensitive crops. The document also provides resources on identifying and managing invasive plant species according to Wisconsin's new invasive species rule.
This document discusses weed management in alfalfa. Weeds can reduce alfalfa establishment, yield, and forage quality. The critical period for weed removal is 3-5 weeks after planting. Herbicides like Pursuit and Raptor can be used during establishment with some potential yield loss. Roundup Ready alfalfa allows post-emergence glyphosate applications with more flexible timing but has higher seed and technology costs. Weed management is important to secure stand establishment and provide high quality forage, especially in the first cutting. Management options depend on weed species, density, and field conditions.
Cereal rye is an excellent winter cover crop that rapidly provides ground cover to prevent soil erosion. It has deep roots that help prevent soil compaction and scavenge nutrients from the soil profile. Rye also helps control weeds when used as a mulch in no-till systems. Rye is easy to grow and establishes well with seeding rates of 60 to 200 pounds per acre. It can be killed with mowing or herbicides to allow no-till planting of other crops while providing weed suppression for about 30 days as a surface mulch.
This document provides information on rice cultivation techniques and varieties in Pakistan. It discusses the botanical classification of rice, the structure of rice plants and seeds, growth stages of rice from germination to ripening, and factors that influence rice yield such as soil selection, variety selection, fertilizer use, and pest management. It also outlines different rice varieties grown in Pakistan's provinces and the soil and climate conditions suitable for rice cultivation. Methods of sowing rice nurseries and transplanting rice are described. Pests that affect rice such as stem borers and plant hoppers are also mentioned.
This document discusses various propagation techniques for small cardamom. It describes seed propagation methods including seed collection, treatment, sowing, and nursery practices. Vegetative propagation through division of rhizomes is also covered. The document outlines micropropagation stages from selection of explants to rooting and acclimatization. Micropropagation provides a means to rapidly multiply planting material through tissue culture. Various growth media and plant growth regulators are used to induce shoot formation, elongation, and rooting.
Seed orchard establishment and management shambhu tiwarisahl_2fast
Â
This document provides an overview of seed orchards, including their establishment, management, and purpose. Seed orchards are stands established to mass produce genetically superior seeds. The first documented pine seed orchard was established in Sweden in 1949, though the concept was applied earlier for other species. Seed orchards can be either seedling or clonal, and are carefully located, designed, established, and managed to promote outcrossing pollination and maximize seed production. Key activities include site preparation, genetic rouging, thinning, pruning, and flower induction. The overall goal of seed orchards is to efficiently produce high quality forest tree seeds to improve forests through subsequent plantings.
Vegetable grafting involves grafting a scion vegetable plant onto a rootstock plant to improve traits like disease resistance, abiotic stress tolerance, yield and quality. The document discusses the history of vegetable grafting, benefits like resistance to soilborne diseases and tolerance to stresses. It also describes different grafting methods like cleft grafting and tube grafting used for various rootstock-scion combinations in vegetables like tomato, eggplant, cucumber and watermelon. Automated grafting has increased grafting efficiency and reduced costs compared to manual grafting. Some examples of vegetable grafting experiments conducted in India are also provided.
This chapter discusses factors for successful jatropha cultivation for oil production, including climate, soil, propagation, and crop management practices. It describes optimal climate conditions as tropical or subtropical, with rainfall between 1000-1500mm annually. Soil should be well-draining sand or loam at least 45cm deep. Propagation can be from seed or cuttings, with seedlings having higher survival rates. Intercropping is common during early establishment, and pruning, weeding, and pollinator presence help maximize yields once mature.
- The System of Rice Intensification (SRI) is an alternative methodology for growing rice that can significantly increase yields using fewer external inputs. It involves transplanting young seedlings with wide spacing, maintaining moist soil conditions, and mechanical weeding.
- SRI has led to increased yields of 8-16 tons/hectare in various countries, compared to average worldwide yields of 3.8 tons/hectare, through profuse tillering, greater root growth, larger panicles, and less water requirement. Additional benefits include lower costs, higher profits, and less need for fertilizers and agrochemicals.
- While counterintuitive, SRI principles take advantage of plant biology and dynamics
Presenter: Norman Uphoff
The Cornell Agroforestry Working Group/ The Management of Organic Inputs in Soils of the Tropics Group (CAWG/MOIST) Seminar Series 2003, USA
The document discusses the System of Rice Intensification (SRI), an alternative methodology for growing rice. SRI uses younger seedlings, wider spacing between plants, and reduced flooding of fields. It results in larger root systems and increased tillering. Studies have found SRI can double average yields to 8 tons/hectare while reducing water use by 50%, costs of production, and need for agrochemicals. SRI appears counterintuitive but reflects farmers' experiences of increased output from fewer external inputs under improved growing conditions.
The document discusses the System of Rice Intensification (SRI), which focuses on managing plants, soil, water and nutrients to induce greater root growth and nurture soil microbial communities. Key points include: SRI practices can lead to higher yields, reduced costs, and environmental benefits compared to conventional rice production. SRI performance may be due to enhanced soil microbial activity and biological nitrogen fixation, which are important for plant nutrition. Further research is needed to fully understand the impacts of SRI management on root and soil microbial dynamics.
The document summarizes the System of Rice Intensification (SRI), an agricultural method developed in Madagascar that has led to increased rice yields using fewer external inputs. SRI involves transplanting young seedlings with wide spacing, minimal flooding of fields, and frequent weeding. Using these techniques, farmers have observed increased tiller and root growth, larger panicles, higher grain weights, and yields that are on average twice as high as conventional methods while using 50% less water. SRI raises rice productivity and lowers costs, making it particularly beneficial for poor farmers and more environmentally sustainable. However, it requires different agricultural skills and practices that challenge conventional understanding of rice cultivation.
The System of Rice Intensification (SRI) is an agricultural method developed in Madagascar in the 1980s that has led to increased rice yields. SRI involves transplanting young seedlings with wider spacing, reducing water levels, and increasing soil aeration. These practices promote increased root and soil biomass growth. Field trials show SRI can increase average rice yields by 50-100% with fewer inputs, while reducing costs, water use, and risks for farmers. SRI is now being adopted by farmers in over 30 countries in Asia, Africa, and Latin America.
This document provides an overview of the System of Rice Intensification (SRI), which is a methodology for growing rice that can produce higher yields with fewer inputs. SRI involves transplanting young seedlings with wide spacing, maintaining moist soil rather than continuous flooding, and incorporating other practices. Key findings from SRI include larger and more extensive root systems, increased numbers of tillers per plant, and higher yields compared to conventional rice growing. While promising, SRI is still being studied scientifically to better understand the mechanisms producing its effects. The document discusses several potential explanations for SRI's results and calls for further research collaboration.
The document discusses the System of Rice Intensification (SRI), an agricultural method developed in Madagascar that can potentially double rice yields while reducing water usage, costs, and environmental impacts. SRI involves transplanting young seedlings with wide spacing, keeping soil well-aerated through alternate wetting and drying, and weeding frequently using a rotating hoe. Preliminary results from several countries show higher yields with SRI compared to conventional methods, though more evaluation is still needed. The document argues SRI merits further investigation as it could boost food security and productivity.
The document discusses the System of Rice Intensification (SRI), a methodology for growing rice that can increase yields by 50-100% with fewer external inputs. SRI involves transplanting young seedlings singly and widely spaced, establishing good soil aeration through weed management, and optimizing water and organic matter. Field trials show SRI rice has larger root systems and outperforms conventional crops despite using less water and fewer chemicals. The document outlines many opportunities for further scientific study of the agronomic and biological processes that contribute to SRI's higher productivity.
The document summarizes the System of Rice Intensification (SRI), an agricultural method developed in Madagascar that can double rice yields while reducing water usage, costs, and environmental impacts. SRI involves transplanting young seedlings with wide spacing, keeping soil well-aerated through alternate wetting and drying, and frequent weeding. Trials in multiple countries show SRI can increase yields from 2-4 tons/hectare to 5-10 tons/hectare or more through synergistic effects on root and tiller growth. The document discusses scientific explanations for SRI's performance and responses to objections about its adoption and labor requirements.
The document discusses the System of Rice Intensification (SRI), an agricultural method that can significantly increase rice yields without requiring additional inputs. SRI achieves this by changing the way plants, soil, water and nutrients are managed through practices like wider spacing of young seedlings, soil aeration, and use of organic matter. Research has found SRI can increase yields by 50-100% while reducing water use by 25-50% and not requiring chemicals. SRI utilizes the natural biological processes in soil and plants to induce a more productive phenotype from any rice variety.
Consultation on Peace, Freedom from Hunger, and Sustainable Development: The Ethical Dimensions M. S. Swaminathan Research Foundation, MSRRF,Chennai, India
The document summarizes the System of Rice Intensification (SRI), which aims to improve rice productivity through a set of principles and practices that change the growing environment for rice plants. SRI promotes greater root growth and more abundant soil biota by using young seedlings, wider spacing between plants, intermittent flooding of fields, and organic matter additions to soil. Preliminary evidence suggests SRI can lead to higher yields with less water and lower production costs compared to conventional rice farming methods.
The document discusses the System of Rice Intensification (SRI), a set of agricultural principles and practices that can increase rice yields and productivity. SRI involves growing rice with wider spacing, younger seedlings, and less water, which promotes root and soil microbial growth. Field trials show SRI can increase yields by 50-100% with reduced inputs. While controversial, SRI results have been replicated in many countries. Further research is needed to understand the mechanisms producing these gains.
The document summarizes the System of Rice Intensification (SRI), an agricultural method that has led to increased rice yields with fewer inputs. SRI involves transplanting young seedlings with wider spacing, reducing flooding of rice paddies, and promoting root and soil microbial growth. Farmers who have adopted SRI have seen rice yields double or more with lower costs, higher profits, and less need for water, fertilizer, and chemicals. SRI is now being practiced in over 30 countries and continues to spread as more farmers and researchers evaluate its methods and results.
Author: Norman Uphoff
Title: Opportunities to Raise Agricultural Production with Water-Saving and with Climate-Change Resilience for Diverse Crops and CountriesOpportunities to Raise Agricultural Production with Water-Saving and with Climate-Change Resilience for Diverse Crops and Countries
Presented at: The Brown Bag Lunch with Foreign Agricultural Service, USDA
Date: November 6, 2017
Venue: FAS/USDA, Washington D.C.
The System of Rice Intensification (SRI) is an agricultural method that can potentially increase rice yields, improve productivity of land, labor, capital and water, and reduce environmental impacts. Key practices of SRI include transplanting young seedlings spaced widely apart in a grid pattern, applying limited water, and doing soil-aerating weeding. These practices encourage deep root growth and increased tillering, leading to higher yields. While SRI was initially developed empirically, scientific study has found benefits like increased nitrogen fixation and phosphorus solubilization in the soil. SRI shows promise for improving global food security and rice production worldwide.
Similar to 0302 A New Paradigm for Rice and Why We Think It Works (20)
Authors: Febri Doni and Rizky Riscahya Pratama Syamsuri
Title: System of Rice Intensification in Indonesia: Research adoption and Opportunities
Presented at: The International Conference on System of Crop Intensification (SCI) for Climate-Smart Livelihood and Nutritional Security
Date: December 12-14, 2022
Venue: ICAR, Hyderabad, India
Author: Bancy Mati
Title: Improving Rice Production and Saving Water in Africa
Presented at: The International Conference on System of Crop Intensification for Climate-Smart Livelihood and Nutritional Security (ICSCI22)
Date: December 12-14 2022
Venue: ICAR, Hyderabad, India
Author: Lucy Fisher
Title: Overview of the System of Rice Intensification SRI Around the World
Presented at: The International Conference on The System of Crop Intensification (ICSCI22)
Date: December 12, 2022
This document summarizes research on using System of Rice Intensification (SRI) methods in Iraq to increase water savings and rice yields. The research found that using SRI with 3-day or 7-day intervals between irrigation used 50% and 72% less water than continuous submergence, and increased yields by 20% and 11% respectively. SRI with 3-day intervals also had the highest water productivity and net economic return, making it a promising strategy for Iraq's water-deficit conditions. The document recommends wider adoption of SRI through incentives, mechanization support, and collaboration with water user associations.
(Partial slideset related to the System of Rice Intensification (SRI)
Presentation at COP26, Glasgow, Scotland
Date: November 2021
Presentation by: Ministereo Desarrollo Agropecuario, Panama
This is a presentation about the SRI activities of the LINKS program, Catalysing Economic Growth for Northern Nigeria, which is implemented by Tetra Tech International Development
Author: Tetra Tech International Development
Title: Reduced Methane Emissions Rice Production Project in Northern Nigerian with System of Rice Intensification (SRI)
Date: October 25, 2021
Willem A. Stoop presents on ecological intensification lessons learned from the System of Rice Intensification (SRI). He discusses two approaches to intensification - conventional using modern varieties, dense planting, irrigation, and chemicals, and ecological using local varieties, low seeding rates, and organic inputs. SRI is presented as an example of an agro-ecological approach using practices like young seedlings, wide spacing, and alternate wetting and drying of soils. SRI results in increased growth, yields, and resilience through enhanced root and soil biology. However, SRI challenges conventional agricultural sciences' focus on increasing planting densities and fertilizer use over soil health and plant spacing.
Speaker: Norman Uphoff
Title: Agroecological Opportunities with the System of Rice Intensification (SRI) and the System of Crop Intensification (SCI)
Date: June 25, 2021
Venue: online, presented in the International Webinar Series on Agroecology and Community Series
Speaker: Khidhir Abbas Hameed,
Al Mishkhab Rice Research Station
Title: System of Rice Intensification SRI
Date: December 9, 2020
Organizer: Central and West Asian Rice Center (CWA Rice)
Venue: online
Author/Presenter: Karla Cordero Lara
Title: Towards a More Sustainable Rice Crop: System of Rice Intensification (SRI) Experience in Chilean Temperate Japonica Rice
Date: November 29-30, 2018
Presented at: The Third International Symposium on Rice Science in Global Health
Venue: Kyoto, Japan
Author: Norman Uphoff
Title: Agroecological Management of Soil Systems for Food, Water, Climate Resilience, and Biodiversity
Date: December 6, 2019
Presented at: The Knowledge Dialogue on the Occasion of World Soil Day
Venue: United Nations, New York
Title: Smallholder Rice Production Practice and Equipment: What about the Women?
Presenter: Lucy Fisher
Venue: 2nd Global Sustainable Rice Conference and Exhibition
United Nations Conference Centre, Bangkok Thailand
Date: October 2, 2019
1. African farmers today are more educated, connected, market-oriented, and aware of issues like climate change than previous generations. They are also more open to new ideas and collective action approaches.
2. Efforts to improve agriculture must consider rural-to-urban migration trends in Africa. While migration is driven by rural challenges, the younger generation remaining in rural areas is more educated and eager for progressive agriculture.
3. Things that should be avoided include mechanization tied to large-scale capital-intensive operations, land grabs, and agricultural models that turn farmers into laborers with no opportunity for management roles. Monoculture and large-scale foreign-owned farming should also be avoided.
Authors: Christopher B. Barrett, Asad Islam, Abdul Malek, Deb Pakrashi, Ummul Ruthbah
Title: The Effects of Exposure Intensity on Technology Adoption and Gains: Experimental Evidence from Bangladesh on the System of Rice Intensification
Date: July 21, 2019
Presented at: USDA Multi-state Research Project NC-1034Â annual research conference on
The Economics of Agricultural Technology & Innovation
Location: Atlanta, GA
More from SRI-Rice, Dept. of Global Development, CALS, Cornell University (20)
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Introduction of Cybersecurity with OSS at Code Europe 2024Hiroshi SHIBATA
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I develop the Ruby programming language, RubyGems, and Bundler, which are package managers for Ruby. Today, I will introduce how to enhance the security of your application using open-source software (OSS) examples from Ruby and RubyGems.
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0302 A New Paradigm for Rice and Why We Think It Works
1. SRI -- The System of Rice Intensification: A New Paradigm for Rice and Why We Think It Works Norman Uphoff Cornell International Institute for Food, Agriculture and Development
Prepared with information available as of February 1, 2003. These slides can be used or adapted, even translated, however SRI colleagues would be useful for explaining this methodology to others.
Picture provided by Gamini Batuwitage, Sri Lanka, of field that yielded 17 t/ha in 2000.
The "economist's $100 bill" refers to the joke about an economist and his friend who were walking together down the street one day when the friend saw a $100 bill on the sidewalk. Thinking that his friend, being concerned with money, would surely pick the bill up, he did not reach down himself. But the economist walked right by. The friend asked, didn't you see that $100 bill on the sidewalk? Why didn't you pick it up? The economist replied,It wasn't a real $100 bill. If it had been genuine, since people are rational, someone would have picked it up by now, so I am sure that it was a counterfeit, and I didn't want to waste any effort on it. Agronomists have regarded SRI with similar skepticism, dismissing it by saying if it were indeed as good as reported, it should have been discovered previously, given the many millions of farmers and thousands of scientists who have worked with rice. So, therefore, SRI must not be genuine. SRI contradicts a number of key concepts held by agronomists and economists, giving them reasons to reject it, without giving it an empirical evaluation. However, the evidence in support of SRI is mounting year by year, month by month.
Average yields where farmers have learned SRI methods, understand them and use them, are about 8 t/ha. In some countries, the average is not yet at that level, but given experience in Madagascar and Sri Lanka, we feel confident that 8 t/ha is a reasonable average to expect with SRI. Maximum yields reported are very controversial. We report data as accurately and truthfully as we can. Farmers have had harvests -- some whole-field, some sampled -- calculated to be 15-20 t/ha, so we report what we think is correct. Over time this will be substantiated by other or not. Water requirement reductions of 40-60% are often reported. That productivity for all four factors of production can increase at the same time goes against the conventional idea of necessary tradeoffs in factor productivity. We have often seen across-the-board productivity improvements, which are more important than yield. Farmers and countries get richer by raising productivity, not by attaining highest yield (because one has to consider the cost of attaining this). Costs of production have been reported to be reduced by 10-50%, depending on how the cost of labor is figured. Because no purchase of external inputs is necessary, cash costs of production invariably go down with SRI. Whether or not labor costs are reduced depends on various factors.
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.
SRI methods have given improved yield and factor productivity with all varieties used so far, though some perform better than others (responding to the different growing environment with more tillering and root growth). Traditional varieties can increase from 1-3 t/ha to 4-10 t/ha with SRI methods, with the highest so far being 13.3 t/ha (Sri Lanka). HYVs and hybrid varieties have given yields in the 15-20 t/ha range. SRI was developed in the 1980s with use of fertilizer, but after subsidies were removed at the end of the decade, Fr. de Laulanie switched to using compost and found that it could give even better yields on most soils, and farmers could be spared out-of-pocket cash costs. We have good reason to believe that compost will give higher yield when using SRI than will chemical fertilizer, seen from factorial trials, because of the impact on soil microbiology. However, farmers can use fertilizer with SRI methods usually cost-effectively. We do not discourage use of fertilizer, but rather encourage use of compost. Similarly, farmers can use agrochemicals (insecticides, fungicides, etc.) with SRI, but most farmers so far have reported that their rice with SRI is resistent enough to pest and disease damage that chemical applications are not necessary, i.e., not cost-effective. We do not know why there is this apparent pest and disease resistance, though we have hypotheses (better and more balanced nutrient uptake with a larger root system reaching lower horizons, better growing conditions when fields are not kept flooded, etc.)
This is usually a minor consideration, though for small farmers this can be important. Savings of 100 kg/ha are often reported with SRI, which is equivalent to a yield increase of 0.1 t/ha. No lodging is generally reported by farmers, though we have no systematic data on this. Also, farmers report that when harvesting SRI rice, there is less loss in the field from panicles. Environmental benefits remain to be evaluated systematically. It is known that emissions of methane are substantial from continuously flooded paddies, so SRI methods can be expected to reduce this greenhouse gas. Possibly the emission of nitrous oxide could increase when fields are not kept flooded, but if inorganic N is not being added in any large amounts, this is not likely to be much of a problem. The only capital requirement for SRI is purchase, or rental, of the hand push-weeder (rotating hoe) that controls weeds which are more of a problem when fields are not kept flooded. The weeder is not necessary, as hand weeding can control weeds. It will not, however, aerate the soil as the push-weeder does. (Herbicides can also control weeds with SRI, but they do nothing for soil aeration.) A study of SRI adoption and disadoption in Madagascar by Christine Moser from Cornell University in 2000, with CIIFAD support, found a good number of very poor households in her sample from four villages not adopting SRI, or giving it up, because they could not afford the additional labor required. Such households needed daily income during the crop season to meet their subsistance needs and could not afford to "invest" their labor in a higher SRI harvest. For them, SRI was "not more accessible." However, in countries such as Sri Lanka, Cambodia and Indonesia, farmers are now reporting that SRI is not more labor-intensive and has become even labor-saving for them. This matter is still being sorted out. But the statement here we think is generally true.
As noted for Slide 7, we are hearing from farmers in a number of countries, that SRI is not more labor-intensive for them. However, we think it best to acknowledge that SRI can require more labor, at least in the first year or two. Studies in Madagascar have put this increase between 25 and 50%, with first-year farmers sometimes even higher. With a doubling of yield, the returns to labor are higher even so. We do not want to minimize -- indeed, we should emphasize -- that SRI requires more skill and knowedge. Farmers are expected not to adopt SRI methods but to gain an understanding of them, particularly why we recommend wide spacing, young seedlings, no continuous flooding, etc. They should adapt the specific practices to their local conditions. SRI was intended by Fr. de Laulanie and Association Tefy Saina to encourage farmers to become more independent thinkings and active innovators. The most objective limitation on SRI is the need for good water control to get best results. Continuous flooding as seen below, leads to root deterioration. Farmers who are part of a cascade (field-to-field) irrigation system will have a hard time managing water for SRI unless there is cooperation among neighbors. Once the economic profitability of SRI has been well established, farmers, governments and even donor agencies should be willing to make investments in improving irrigation infrastructure to make SRI management possible.
This slide gives the most essential understanding of SRI. These ideas come from the work of Fr. de Laulanie and from five years of student thesis research in Madagascar and experimentation by a growing number of scientists in countries outside Madagascar. These generalizations remain to be fully documented and calibrated by additional research, but we are confident that this "core" of SRI is solid.
We emphasize that these are "starting point" because farmers are expected and encouraged to do some experimentation and adaptation with these practices, based on their understanding of the core concepts. The reasons for transplanting young seedlings are given in Slides 34-39. Quick and careful transplanting is necessary so there is little or no trauma to the young roots, which would set back their subsequent growth. We recommend that the roots be laid gently into the soil, only 1-2 cm deep, with the root straight downward or at least horizontal (L-shaped) rather than being plunged vertically down into the soil which causes the tip of the root to invert back upwards (J-shaped). When there is such inversion, it takes days, even weeks, for the root to reposition itself for resumed downward growth. Single plants spaced widely have room for both the roots and canopy to grow vigorously, as they will with young seedlings and aerated soil. We recommend starting with 25x25 spacing, but with good soil (and the soil usually improves year-to-year with SRI culivation), higher yields will be achieved with 30x30 or 40x40 spacing. The highest yield we know was with 50x50 cm spacing once soil had been improved by plant, soil, water and nutrient management. So farmers should experiment with wider spacing each year to see whether it leads to better crop performance than 25x25. They can experiment with narrower spacing if they like. No continuous flooding at least up to panicle initiation is key. This can be done, however, either by adding small amounts of water each day to keep the soil moist but not saturated, and not watering the field for 3-6 days several times during the growing season to dry out the field, up to the point of surface cracking; or by flooding the field for 3-6 days, and then draining it and leaving it dry for 3-6 days, until there is enough cracking to make reflooding necessary. We are still learning how to manage water for best effect with SRI. The best practices for any particular farmer will surely depend on soil, climatic, topographic and other variables. We recommend that farmers keep 1-2 cm of water on the field after panicle initiation, up to 10 days before harvest when the field should be drained (as done with all irrigated rice cultivation systems). Possibly the soil should be kept more aerated than this after panicle initiation, but no systematic research has been done. Weeding is important, for soil aeration as well as removal of weeds. See Slide 44.
The data summarize our observations and measurements. Regarding panicle size, we have had single panicles with as many as 900 grains, but this is so fantastic, few will believe it. The maximum of number of fertile tillers observed so far is 140, with 50x50 spacing. The most important phenotypic difference is the last one, discussed in Slides 21-22.
This begins a consideration of the "science" behind SRI. This statement from an article by a number of leading rice scientists, published in a leading agronomy journal, states the standard scientific understanding of how irrigated rice grows: if there are more panicles per plant, there will be fewer grains per panicle, a manifestation of "the law of diminishing returns." This means that it is unpromising to increase rice plant tillering substantially, so rice breeding strategies, and particularly the "super-rice" being developed at IRRI, have aimed to reduce tillering. We find that with SRI methods, as seen in the next slide, there is a POSITIVE correlation, as plants with more panicles also have larger panicles. This is because SRI plants maintain a large and intact root system, as discussed below, making them "open systems" in which there is no necessary tradeoff (partitioning of photosynthate) between tillers and grains. With root degradation under continuously flooded conditions, rice plants are "closed systems" and there is a zero-sum relationship between tillering and grain-filling.
This 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.
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.
This helps to explain our problem of "the agronomists' $100 bill." SRI is quite "counterintuitive." Indeed, it even sounds crazy. But we have experience and evidence that this "less is more" dynamic operates, and subsequent slides provide a number of scientific explanations for why fewer or smaller inpouts produce more in the case of irrigated rice
This figure is from research 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 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.
Usually we find researchers getting higher yields with new methods and farmers having difficulty "replicating" those results on their own fields. With SRI, we have often the opposite situation: researchers get lower yield on-station than farmers get in their fields. This remains to be thoroughly documented and fully explained. Fortunately, there is growing interest from crop and soil scientists after a number of years of skepticism and even resistance. We want to acknowledge, and express our appreciation for, the work of Fr. Henri de Laulanie, who developed SRI as a labor of love and innovative "lay science" during 34 years of living in Madagascar. He came there from his native France in 1961 and synthesized SRI first in the 1983-84 season. He had been educated in agriculture at the best French agricultural university (ENA) before World War II (1937-39) and before entering a Jesuit seminar (1941-45). So he knew basic agricultural science. But he had not learned about rice in France, so learned about it from and with farmers. The following slide shows Fr. de Laulanie visiting a farmers' field shortly before he died in 1995. In 1990, with his friends Sebastien Rafaralahy and Justin Rabenandrasana, Fr. de Laulanie formed Association Tefy Saina, a Malagasy NGO dedicated to improving rural conditions in Madagascar, including through the dissemination of SRI. Sebastien and Justin, now President and Secretary-General of Tefy Saina, are seen in Slide 17.
The first SRI evaluation outside Madagascar was done by Nanjing Agricultural University in China in 1999, getting 9.2-10.5 t/ha yields in three trials. Such yields can be attained in China using hybrid rice varieties and substantial inputs, but they could not be obtained using only half the usual amount of water. This is an important consideration in China where water for agricultural use is in increasingly short supply. Next, results came from AARD's Sukamandi rice research station. The first season gavie 1-1.5 t/ha higher yield than farmer practices, but the second season's yield reached 9.5 t/ha, spurring interest. After three years of evaluation, AARD made SRI part of its new "Integrated Crop and Resource Management" (ICM) strategy to get rice yields rising once again. Other countries learned about SRI through CIIFAD, through the International Institute for Rural Reconstruction, through ILEIA in the Netherlands, through ECHO in Ft. Myers, FL, and other channels. In April 2002, with a grant from the Rockefeller Foundation and CIIFAD support, an international meeting was held in China, hosted by the China National Hybrid Rice Research and Development Center and its director, Prof. L. P. Yuan. The proceedings include reports from 15 countries where SRI had been tried already, often with spectacular success, and only sometimes without seeing "the SRI effect" (Thailand, Nepal, Laos). The next slide gives a summary of results reported from the 10 countries where there had been most experience with SRI as of early 2002.
The bolded numbers are arithmetic averages for a number of SRI trials/evaluations in each country. Some of the data sets are from on-farm trials (with the number of farmers involved shown in parentheses) or from on-station trials. The range of results reported is also shown in each cell. The Comparison Yield figures are not national average figures, often lower, but averages for the trials or farmer practice using standard cultivation methods. The Maximum SRI yields are the highest yields reported in each data set.
Bruce Ewart, ADRA representative in Indonesia, got 7 farmers in West Timor to try SRI methods in 2002, with the encouragement of Roland Bunch. These are better farmers than their peers, as seen from their yield that season with current methods (4.4 t/ha), more than double the usual yield in the area. Their SRI plots averaged 11.7. Farmers working with ADRA in Lampung, Sumatra, got 8.5 t/ha with SRI methods compared to their usual production of 3 t/ha. Pablo Best reported that when farmers in Pucallpa, a lowland jungle area, tried SRI, they got a yield of 8 t/ha, four times their previous average, and not needing to do 8-10 hours/day of bird scaring at the end of the season because with SRI, the heavy panicles hung downward (but not lodging) so that birds could not get to them. Instead of letting cattle graze on the regrowth after harvest, the rice was allowed to produce a second (ratoon) crop, which was 5.5 t/ha, 70% of the first. Controlled trials in Benin, having read the account of SRI in ECHO Development Notes, found about a 5-fold difference in yield between SRI and conventional practice. The Agricultural Training Institute in the Philippines tried SRI methods with three varieties in Cotabato, Mindanao, and got an average yield of 12 t/ha, three times the usual yield in that area. The economic return averaged 290% as the value of rice produced was almost four times the cost of production.
To get a systematic understanding of how the different factors brought together in SRI contribute to greater yield, two top students in the faculty of agriculture at the University of Antananarivo did baccalaureate thesis research involving large-scale factorial trials in 2000 and 2001. Jean de Dieu Rajaonarison did his study near Morondava on the west coast of Madagascar at the Centre de Baobab. He did not vary soil quality (the soil there was poor sandy soil, sable roux) but evaluated SRI effects with different varieties (half of the 288 plots were planted with a high-yielding variety and half with a local variety). Andry Andriankaja did his study in the village of Anjomakely 18 south of the capital Antananarivo, on the high plateau and on farmers' fields. He used the same variety (riz rouge) on two different kinds of soil (better clay and poorer loam). These were contrasting locations agroecologically as the Morondava site was near sea level, with tropical climate and poor soil, while the Anjomakely site was about 1200 m elevation, with temperate climate, and better soils. Both varied water management (aeration according to SRI principles vs. continuously saturated soil), seedling age (8 days vs. 16 days at Morondava and 20 days at Anjomakely, these latter ages being equivalent given differences in ambient temperature), plants per hill (1 vs. 3), and fertilization (compost vs. NPK vs. none as a control with the Morondava soils). Spacing was 25x25 or 30x30, but both were within the SRI range and gave no significant difference (absolutely no difference in Morondava and only 80 kg/ha at Anjomakely, other factors being equal). This was in a way a "mistake" in research design, as we should have compared a SRI and non-SRI spacing. But because there was no significant difference according to the spacing factor, we could combine those trials, having thus SIX replications for all of the averages calculated for the 48 combinations at Morondava and 40 combinations at Anjomakely.
Note that conventional practices -- 20-day seedlings, 3/hill, in saturated soil, with NPK amendments -- give 2-3 t/ha, while all-SRI practices -- 8-day seedlings, 1/hill, aerated soil, with compost -- give more than 3 times greater yield. (Note also that weeding and spacing were not varied in these factorial trials, which would have doubled the number of plots needed to 480, assuming just 3 rather than 6 replications.) The individual practice adding most to yield was young seedlings, then aerated soil, then single seedling, then compost. Pooling results from better and poorer soil (last column), we see that going from 75% to 100% SRI adds more to yield (almost 2 t/ha) than going from 0 to 25%, 25 to 50%, or 50 to 75%, an indication of synergistic effects among practices. The pattern of increase was similar for the trials at Morondava on poorer soil, with SRI practices increasing the HYV yield from 2.84 to 6.83 t/ha for the HYV and from 2.11 to 5.96 for the traditional variety, by 2.4 and 2.8 times respectively.
Here we look just at the effect of young seedlings, on better and poorer soil, at Anjomakely. The synergistic effect of compost with aerated soil is seen in the bottom three lines. 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).
These are comparisons of resuls for the two sets of trials, looking at "other things being equal" effects. The averages shown are calculated for sub-samples (N= 144 in the Morondava study and N = 120 in the Anjomakely study) where all of the other practices than the one singled out for evaluation were an EQUAL NUMBER of SRI and non-SRI practices. These comments apply for the next slide as well.
This slide speaks for itself. The Kirk and Solivas statement was for flooded rice 29 DAT. This exact number can vary according to variety, soil type and irrigation practices, but it is agreed that the roots of continuously flooded rice remain in a "mat" near the surface, because the roots are trying to capture dissolved oxygen in the irrigation water. In such a situation, the roots begin degenerating after about 2 weeks of continuous flooding, as documented by Kar et al. There is practically no research on this process, since it has been characterized as "senescence" and thus as a natural (and an unavoidable) biological process. In fact, as the research by Puard et al. shows, the formation of aerenchyma (air pockets) in rice roots under flooding is a man-made process, leading to root degeneration.
This slide speaks for itself. The Kirk and Solivas statement was for flooded rice 29 DAT. This exact number can vary according to variety, soil type and irrigation practices, but it is agreed that the roots of continuously flooded rice remain in a "mat" near the surface, because the roots are trying to capture dissolved oxygen in the irrigation water. In such a situation, the roots begin degenerating after about 2 weeks of continuous flooding, as documented by Kar et al. There is practically no research on this process, since it has been characterized as "senescence" and thus as a natural (and an unavoidable) biological process. In fact, as the research by Puard et al. shows, the formation of aerenchyma (air pockets) in rice roots under flooding is a man-made process, leading to root degeneration.
These pictures of cross-sections of rice root, from French research. The upper-left cross-section is of an 'upland' variety grown under upland, i.e., unflooded, and the lower-left, the same variety grown under flooded conditions. The upper-right cross-section is of an 'irrigated' variety grown under flooded conditions -- note the larger, more regular air pockets formed by degeneration of the root's cortex -- and the lower-right, of the same variety grown under unflooded conditions. There is every reason to believe that the upper-left and lower-right cross-sections are the more 'natural' or 'normal' condition, and that the lower-left and upper-right represent adaptations, for the plant root tissues to survive longer as oxygen can diffuse through these air pockets. But this will not keep the tissues alive throughout the growth cycle, as seen from Slide 29.
This is the abstract for an article that documented this process of root degeneration. Unfortunately, it was published in a little-read journal. The exact number (78%) can vary according to variety, soil type, etc., but this phenomenon is well known. Only it is not regarded as a serious impediment for rice production.
This is a figure also 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 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.
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.
This gets into the most complicated part of the explanation for SRI success, drawing on knowledge that is available in the literature but seldom known by scientists who do not read Japanese or who did not have teachers educated in Japan. T. Katayama studied tillering in rice, wheat and barley during the 1920s and 1930s, but never published his results until after the war (1951), and his book has not been translated into English. Fortunately, Fr. de Laulanie happened to read a book in French which reports on Katayama's concept of "phyllochrons," regular intervals of plant growth (emergence of phytomers -- units of a tiller, a leaf and a root -- from the apical meristem of grass family (gramineae) species. In rice, phyllochrons can be as short as 5 days with good growing conditions, but as long as 8-10 days with adverse conditions. The number of phyllochrons emerging in consecutive periods increases according to a regular pattern known in biological science and mathematics as "a Fibonacci series," where the number emerging in each period is equal to the total the numbers that emerged in the preceding two periods. [Look at numbers in bottom line of the slide, and then at the numbers for rice tillering in the next two slides]
In the first phyllochron (about 5 days, but it can be longer), the main tiller (and main root) emerge. Then no more tillers or roots emerge during the next two phyllochrons. This is the best time for transplanting because it minimizes root trauma. In the 4th phyllochron, a first primary tiller emerges from the base of the main tiller, and a second primary tiller emerges during the 5th phyllochron. In the 6th phyllochon, two tillers emerge, one from the main tiller (the third primary tiller) and one from the first primary tiller, because from the 4th phyllochron on, each tiller begins producing tillers, one per phyllochron, after a lag of two phyllochrons (periods). This can be seen from the next slide. The numbers start adding up quickly, as seen from the bottom row -- PROVIDED THAT THE PLANT HAS AN INTACT ROOT SYSTEM AND IS ABLE TO SUPPORT SUCH PROFUSE GROWTH. If the root system is not fully functioning, the phyllochrons lengthen and fewer are completed before panicle initiation (PI) when the rice plant switches from vegetative growth to reproduction and grain filling. This table shows tillering if the plant can complete 12 phyllochrons (periods) of growth before PI. Some SRI plants have have over 100 tillers, meaning that they got into the 13th phyllochron before PI. Under unfavorable growing conditions, phyllochrons become longer and few are completed before PI. A plant going through only8 phyllochrons of growth would have only 13 tillers, not 84. Note the geometric progression of groups of three phyllochrons, exhibiting a mathematical power relationship. The reason there are not 64 in the last period (phyllochrons 10-12) is that there is no room in the first row of tillers for a seventh tiller. Remember also that the growth of roots mirrors that of tillers, so the root structure multiplies similarly, provided that growing conditions are favorable. This table was worked out by Fr. de Laulanie, following the lines of observation and analysis laid out by Katayama.
This shows graphically what happens according to the numbers shown in the preceding table (Slide 35). Note that with SRI practices, which create a large and actively functioning root system for the plant, there is no fall-off in tillering before PI. With conventional rice growing practices, a period known as "maximum tillering" PRECEDES panicle initiation, as the earlier growth in tillering rate 'peaks' and subsides. We need more systematic monitoring of tillering rates in SRI and conventionally grown rice to put some parameters on this difference. But we know that this kind of "explosion" in tillering does occur with proper use of SRI practices, which support a large root system, and we know that "maximum tillering" occurs before PI with conventional plants.
This slide summarizes the plant physiological (but not the soil microbiological) elements of our 'theory' of SRI. It is informed by the article by Nemoto et al. in CROP SCIENCE (1995), the most explicit article we have found in English on phyllochrons in rice. The left-hand column are conditions that accelerate rice plant growth, i.e., shorten the phyllochron so that more of these periods are completed before PI. The right-hand column lists opposite conditions that slow plant growth. We refer to this, metaphorically, as 'slowing down vs. speeding up the biological clock,' a way of speaking about the rate of cell division and growth. The last two conditions, moisture and oxygen, are inversely correlated in that too much moisture means too little oxygen. Water management with SRI seeks to optimize moisture and oxygen in the root zone, ensuring enough of either, steering between drought and hypoxia. When plants are to close together, their roots (and canopies?) sense that there will not be enough nutrients, moisture, etc. to support maximum plant growth through the entire plant cycle to where the plant can produce mature seeds to ensure a next generation. Plant growth slows in response to the right-hand conditions in order to make more likely that at least some seeds will be produced before the plant senesces. When all of these conditions are favorable, growth speeds up. Raising yield requires providing ideal or optimal conditions. There is not much research done on phyllochrons in rice with regard to their manipulation or use for increasing production. Fr. de Laulanie thought that once we fully understand and utilize phyllochron dynamics, rice yields can be moved into the 20-30 t/ha range, given the inherent genetic potential of rice plants when ideal growing conditions are provided.
Young seedlings, transplanted before the 4th phyllochron, can respond more prolificly to these various favorable conditions than older seedlings, for reasons not well understood. It is important that there be no trauma to the rice plant root during transplanting, followed then by favorable soil, temperature, water, nutrient and other conditions. The logic of this analysis suggests that direct seeding could be made as or more productive as transplanting. We have some initial evidence that there is no loss of yield with direct seeding. This is an area where farmers and researchers should start doing systematic evaluation.
This summarizes what we know about phyllochrons and their effect on rice plant performance. It reiterates the need to consider what is happening below ground, with the roots, even though they are not seen. They are the basis for increased productivity, in conjunction with a more microbiologically active rhizosphere.
This picture was provided by Koma Yang Saing (CEDAC) of a pleased Cambodian farmer, showing the size of a massive root ball with a SRI rice plant.
This is known by plant scientists, but it has not been integrated into agronomic research strategies. There is a saying, "you can lead a horse to water, but you cannot make it drink." We want to emphasize that "you can provide large amounts of N to rice plants' roots, but you cannot make the roots take N up unless the plant needs it." This probably applies for other nutrients, but we have not seen research on this. The statements cited here are from IRRI and Cornell agronomists. The usual reaction we get hen pointing this relationship out is that this is already known, nothing new. It helps to explain why average uptake (efficiency) of N application is in the range of 20-30%.
SRI experience, buttressed by the preceding slide, suggests that we take a "demand-driven" view of N uptake and plant growth, rather than the prevailing "supply-side" approach. The latter is based on a misconception about how and why rice takes up N. The rapid explosion of tillering in the latter stages preceding PI creates a greater demand for N, and the larger canopy and roots during reproduction and grain filling also increase demand for N. It sounds incorrect to suggest "grow it and the N will come," because this suggests that demand will create its own supply. (This proposition is rejected because economists have correctly rejected Say's Law). However, as discussed below, with SRI, once we understand better the neglected role of soil microorganisms, we can see how subsurface processes can indeed provide N and other nutrients to the rapidly growing plant. There is not enough systematic evidence on rates, amounts, conditions, etc., to speak precisely about this matter, but we have the results of SRI practice to show that the needed nutrients must be coming from somewhere -- and they are not coming from inorganic additions.
This is a table from research done in 2001 in Madagascar by Barison for his MS thesis in agronomy at Cornell. He studied a sample of 108 farmers who used both SRI and conventional practices on their farms, so that the comparison of rice plant performance controlled for both farmer and farm differences. He used the QUEFTS model for analyzing yield response to inputs of nutrients (N, P and K) and found that SRI plants plateaued at a yield double that of conventional plants, 10 vs. 5 t/ha. The response of SRI vs. conventional plants was the same for both P and K. This showed that the soil-nutrient-root-shoot interactions were markedly different for plants grown with SRI methods.
This figure shows the yields associated with different numbers of mechanical hand weedings (with rotating hoe) for 76 farmers around Ambatovaky in 1996-97 (same as Slide 22). Two farmers did only manual weeding. They got about 6 t/ha yield, more than double the typical yield in the area. The 35 farmers who did 1-2 weedings, the minimum recommended, got 7.5 t/ha, triple the typical yield. The 24 who did 3 weedings got 9.2 t/ha, four times more, while the 15 who did 4 weedings, got 11.7 t/ha, about 5 times. Beyond 2 weedings, we think that the benefit is not really from the weeding but from the active soil aeration during the latter part of the vegetative growth phase. This is an area where controlled studies should be done. So far, all we have is data from farmers' fields. In other soils and other conditions, the absolute numbers will surely be different, but we think the pattern will hold up. On the very poor soils around Morondava, Frederic Bonlieu, doing research with 72 farmers practicing SRI for his thesis from Angers University in France, found that additional weedings added about 0.5 t/ha to yield, other things being equal. The same pattern we seen, but it was more linear and with less increment per weeding.
These last slides get into an area of SRI explanation that is more tentative, but probably more important for highest SRI yields. There is a lot of country-to-country variation in SRI results, and also within countries, much larger variations than can be explained by differences in practices or by differences in soil chemical and physical properties. We cite an observation by S. K. DeDatta in his well-known text on rice. We add our own emphasis to underscore our conclusion that there needs to be much more consideration of soil microbes and their contributions to rice yield. There is, however, little research on this subject, so DeDatta devoted very few pages to this compared to genetic, soil and other factors.
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.
Most people know that leguminous plants "fix" N in their roots through nodules on the roots inhabited by certain bacteria, rhizobia. And by implication, most thinks that non-leguminous plants "do not fix nitrogen." This is correct in terms of locus, but it misleads. All of the gramineae species (rice, wheat, sugar cane, etc.) have free-living bacteria in their root zones (referred to as 'associated' microbes) that fix N. Even in fertilized crops, a majority of the N taken up by the roots is from organic sources. And there is evidence that adding inorganic N to the root zone inhibits or suppresses the roots' and microbes' production of nitrogenase, the enzyme needed to fix N. So there is a tradeoff, in that adding inorganic N fertilizer reduces the N that is produced by natural biological processes. Or most relevance to SRI is research published more than 30 years ago reporting that when aerobic and anaerobic horizons of soil are mixed, BNF increases greatly compared to that originating from either aerobic or anaerobic soil. This suggests that the water management and weeding practices of SRI could be actively promoting N production in the soil. We have no research results to support this inference (though see data in Slide 49), but the yield increases with SRI practices require large amounts of N. BNF is the most plausible explanation.
Johanna Dobereiner has spend almost 40 years working on BNF particularly in sugar cane in Brazil, but also looking at BNF in other non-leguminous crops. Her 1987 book is the most extensive consideration of this subject, though there are a number of symposia also providing scientific information. In Brazil, it is well documented that BNF provides 150-200 kg/ha of N to the crop -- provided that soil has not been previously fertilized with inorganic N for some years, and provided (this is a little hard to understand) the sugar cane cultivars have not been fertilized for several generations. Applying N to the soil or to cultivars inhibits production of nitrogenase needed for BNF. Dobereiner's work is regarded as "controversial" within the agronomy profession because many efforts to replicate her results have failed. But this could be due to a mechanistic (non-biological) concept of the process, not appreciating how prior use of inorganic N can affect BNF potential, an effect documented in the literature (see van Berkum and Sloger).
These data from a study done by Fide Raobelison under the supervision of Prof. Robert Randriamiharisoa at Beforona station in Madagascar, and reported in Prof. Robert's paper in the Sanya conference proceedings, 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 "indicator species" 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 such as the Anjomakely factorial trials (Slide 24) and the previous season's trials with SRI at Beforona (10.2 t/ha).
These data are taken from the article by Ladha et al. (1998) but they did not draw any implication from their finding that optimum N fertilizer application was LOWER for late-maturing varieties than for early-maturing varieties -- and that the late-maturing varieties had higher yield with less fertilizer application than did early-maturing varieties. If volatilization and leaching of nutrients, particularl N, is as big a problem as stated in the article, these numbers should have been reversed. If, on the other hand, the N applied can "prime" soil microbiological processes that contribute to plant nutrition, a smaller amount over time could give higher yield. This is speculation, but it is consistent with relationships observed with SRI. It seems worth exploring.
The increase in yields around Ranomafana National Park during 1994/95-1998/99 from 2 t/ha to 8 t/ha ith SRI were quite inexplicable given that soil analyses by North Carolina State found on average that available P was only 3-4 ppm, which is less than half the minimum usually considered necessary for an acceptable yield. SRI farmers got twice as much as an acceptable yield without adding any P to the soil. Where did the P come from? The research reported by Turner and Haygarth in NATURE (May 17, 2001) could explain this since SRI methods involved alternate wetting and drying of the soil which the authors showed greatly increased levels of P in the soil solution, almost all from organic sources. They suggested that this effect probably applies for other nutrients too, but they were measuring only P.
Mycorrhizal associations have been largely ignored in rice because most is grown under continuously flooded conditions, which are inhospitable to growth of funguses. Yet we now know that 80-90% of plants depend in small to large part on the nutrient acquisition of funguses that &quot;infect&quot; their roots and provide access to a much larger volume of soil through the network of hyphae (filaments) that spread out in all directions. These hyphae acquire water and nutrients that ar shared with the plant, particularly P but also many others. Mycorrhizal hyphae are thinner even than hair roots so can access places in the soil that the root system cannot. One study found that &quot;infected&quot; plants could grow as well with 1/60th as much P in the soil as could &quot;uninfected&quot; plants, reported in the review on mycorrhizae by M. Habte and N.W. Osorio, Mycorrhizas: Producing and applying arbuscular mycorrhizal inoculum (2002). This is available on the web in The Overstory, #102 <http://agroforester.com/overstory/ovbook.html>
Research conducted in Egypt where farmers have for centuries alternated growing rice and berseem (clover) has shown that free-associated rhizobia in the root zone of rice (not living in nodules as they do on a legume) are abundant in this soil and have many measurable beneficial effects on rice growth. Surprisingly, the rhizobia do not contribute BNF for rice. Instead they stimulate nutrient uptake and plant growth in other ways. More research should be done on this particular microbe to understand what it could contribute to plant growth more generally. See Y. G. Yanni, et al., The beneficial plant growth-promoting association of Rhizobium leguminosarum bv. trifolii with rice roots, AUSTRALIAN JOURNAL OF PLANT PHYSIOLOGY, 28 (2001), pp. 845-870.
Research on rhizosphere function and dynamics is increasing. See the literature review by Robert Pinton et al., THE RHIZOSPHERE: BIOCHEMICAL AND ORGANIC SUBSTANCES AT THE SOIL-PLANT INTERFACE (Marcel Dekker, 2000) which gives an up-to-date review of what is currently known about this domain, with chapters on root exudation,rhizo- deposition, the contributions of mycorrhizae, etc.
This review of what is known, and what we think we know, about SRI is not a conclusive or final discussion of the subject. We expect that in 3-5 years' time, much more will be known as scientists become engaged on these topics and as farmers and NGOs continue producing new data that begs for explanations. The two main areas for research that have emerged from our SRI experence is (a) the growth and performance of roots, and (b) the dynamics and contributions of soil microbes. Both of these areas of research should be useful for improving the production of other crops. The explanations for greater root growth with SRI are quite straightforward: young seedlings, wide spacing, aerated soil. What results from this remains to be better documented and explained.
More complicated and difficult to examine and understand than roots will be soil microbial dynamics, though these two subjects should be looked at jointly, not totally separately. The contributions of exudates to microbial growth are well documented in Pinton et al. (2001), but we do not know much about this process for irrigated (SRI) rice.
This is a SRI rice nursery in Sri Lanka, showing one way (but only one of many ways) to grow young seedlings. The soil in this raised bed was a mixture of one-third soil, one-third compost, and one-third chicken manure. (The flooding around it is because the surrounding field is being readied for transplanting; normally there would not be so much water standing around the nursery.)
Here the seedlings are being removed. We would recommend that they be lifted with a trowel, to have minimum disturbance of the roots, but these seedlings are so vigorous that this manual method is successful. This farmer has found that his seedlings, when transplanted with two leaves at time of transplanting, already put out a third leave the next day after transplanting, indicating that there was no transplant 'shock.'
Here the field is being 'marked' for transplanting with a simple wooden 'rake.' If the soil is too wet, these lines will not remain long enough for transplanting. There are drains within the field to carry excess water away from the root zone.
Here are seedlings being removed from a clump for transplanting. Note that the yellow color comes from the sunlight reflecting off the plant. The plant's color is a rich green, indicating no N deficiency.
Here the seedlings are being set into the soil, very shallow (only 1-2 cm deep). The transplanted seedlings are barely visible at the intersections of the lines. This operation proceeds very quickly once the transplanters have gained some skill and confidence in the method. As noted already, these seedling set out with two leaves can already have a third leaf by the next day.
The SRI field looks rather sparse and unproductive at first. Up to the 5th or 6th week, SRI fields look rather miserable, and farmers can wonder why they ever tried this method and 'wasted' their precious land with such a crazy scheme. But the SRI plot here will yield twice as much rice as the surrounding ones once the rapid tillering (and root growth) begins between 35 and 45 days.
This is one of many happy Sri Lankan farmers with his SRI field nearing harvest time. Some young farmers have taken up growing &quot;eco-rice,&quot; i.e., traditional varieties grown organically to be sold for a much higher price than conventional HYV rice, because of better texture, taste, smell and aroma and more assurance of healthy food. SRI in this way is starting to contribute to the preservation of rice biodiversity. As noted above, SRI methods work well with hybrid varieties and HYVs. These give the highest yields with SRI methods. But as SRI methods can double or triple traditional-variety yields, these old varieties become economically more advantageous with SRI. Much more remains to be learned about and from SRI. But we have now enough accumulated evidence, based on experience in farmers' fields, not just on experiment stations, and consistent with what is known in the literature (though often not previously connected up to promote increased rice productivity), to have confidence that this methodology will contribute to greater food security and a better environment. SRI, developed by Fr. de Laulanie and promoted by his friends in Association Tefy Saina, and by a growing number of colleagues in many countries around the world, could help to improve other crop production. The world does not need a doubling of rice production, but it does need increased productivity in the rice sector, as this is the largest single agricultural sector in the world in terms of the resources devoted to it. By raising the productivity of land, labor, water and capital in the rice sector, we should be able to meet our staple food needs with less of these resources, which have significant opportunity costs. We hope that SRI methods will enable farmers to redeploy some of their land, labor, water and capital to producing other, higher-value and more nutritious crops, thereby enhancing the well-being of rural households and urban populations. The urban poor should benefit from lower prices for rice that will follow from higher productivity. SRI is not a labor-intensive method that will 'keep rice production backward,' as was alleged by its critics in Madagascar for many years, but a strategy for achieving diversification and modernization in the agricultural sector.