Expert Consultation on Yield Gap and Productivity Decline in Rice Production: conclusions and recommendations

INTRODUCTION

Twenty-seven rice experts from Australia, Brazil, Colombia, Egypt, India, Italy, the Republic of Korea, Nigeria, the Philippines, the United States and Venezuela, the International Rice Research Institute (IRRI), the West Africa Rice Development Association (WARDA), the International Atomic Energy Agency (IAEA) and FAO attended the Expert Consultation on Yield Gap and Productivity Decline in Rice Production. The expert consultation was held at FAO in Rome from 5 to 7 September 2000. This article outlines its conclusions and recommendations.

YIELD GAP

Definition of the term "yield gap"

The potential yield for a variety ´ environment combination is derived from modelling with optimum growth conditions. It is the highest yield that can be used for breeding higher-yielding varieties.

Under practical field conditions, only 80 to 85 percent of the potential yield can be achieved for a given variety ´ environment combination. Thus the practical yield gaps can be defined as follows:

Yield gap 1: the difference between research (experiment station or on-farm research plots) and average farmers' yields in any given location.
Yield gap 2: the difference between the mean yield of large plot demonstrations or top 10 percent of farmers (using the presently available improved technologies and management practices in the best possible combination) in a given location and the average yield of all farmers for that location.

The consultation observed that the yield gap ranges from 10 to 60 percent between attainable and economically exploitable yields depending on the ecosystem and country.

Guidelines for the identification of yield gaps

Research yields are mostly derived from experimental plots and records are available from research stations. Average farmers' yields should be obtained from sources such as farm surveys, including sample crop-cut studies, and/or from official yield records for the chosen locations (village, district, province or pilot sites). Mechanisms should be put in place to update the information on yield gaps on a regular basis.

Causes of yield gaps

The expert consultation identified the following constraints as key contributors to the yield gap:

Biophysical: climate, soil type, water availability, pest pressure.
Socio-economic: farmers' resource levels, educ-ation, skills, attitudes.
institutional/policy: infrastructure, land tenure, credit and inputs supply.
Technical/management: varieties, resource use efficiency (water, soil, nutrients), seed quality, pests, weeds, harvest and post-harvest management.

GUIDELINES FOR CLOSING YIELD GAPS

Identify the target group or factor to change: farmers, socio-economic, institutional/infra-structure, and/or policy support groups.
traits are difficult to change, but varietal selection and good crop management practices can be used to mitigate the effects of biophysical constraints to a certain extent.
the constraining factors involve socio-economic, institutional and/or policy areas that are outside farmers' control, then efforts should be made to address these problems at the policy level.
Develop a checklist to identify and prioritize the technical constraints. A model checklist might include: rice field infrastructure; rotation in cropping systems; rice varieties; seed quality; time of sowing; crop establishment; crop protection (weeds, pests, diseases, integrated pest management [IPM]); nutrition (nitrogen and other nutrients, integrated nutrient management); water management; harvesting; and post-harvest management to reduce losses and improve grain quality.
Using such a checklist, identify the technology options required to address the critical constraints to narrowing the yield gap.
objective crop management recommen-dations to assist farmers and growers to meet their crop management and yield targets for a given location. This process can assist growers in evaluating their own management performance, identifying strengths and weaknesses, and taking action to improve management for subsequent crops. An example of this approach is the Australian Ricecheck system (a tropical ricecheck for targeted areas) and similar models used in Egypt and Korea.
Develop mechanisms to evaluate, refine and deliver the recommendations in close collaboration with farmers, for example, through the government extension service, non-governmental organizations, voluntary organizations, private sector agencies, farmers' groups or grower associations.
Use farmer discussion groups to promote the adoption of a system of Ricecheck recommendations and specific technologies that require greater emphasis. Discussion groups provide an opportunity to use the farmers' skills and experiences to reinforce and modify the recommendations.
Extension officers require skills in group facilitation as well as a sound technical knowledge.
Ensure the availability of inputs, credit and other incentives necessary to facilitate farmer adoption of the recommended practices. This process provides an additional opportunity to involve agribusiness in providing inputs, services and technical support to farmers.
Extension staff should monitor the crop performance and yields over time, identify emerging problems (if any) and provide feedback to researchers with the aim of finding solutions through relevant research.
Disseminate successful management options among farmers and others through appropriate communication strategies designed for a wider impact, for example, large field demonstrations, messages, guidelines, decision support systems, timing for various operations, and warnings of pest outbreaks in print and on radio, television and the Internet.
Ensure that an effective research and extension infrastructure is available to address problems and to provide technical support to farmers. This will strengthen the linkage between research, extension and farmers.

Recommendations for national and international action in the medium term (2001-2005)

Raise awareness of yield gaps and factors causing yield gaps among all stakeholders (farmers, extension staff, researchers, government decision-makers and others). For example, FAO can organize and facilitate dialogue with national governments to address the policy-related issues responsible for yield gaps.
The collaboration among FAO, IRRI, WARDA, the International Centre for Tropical Agriculture (CIAT) and the Fund for Latin American and Caribbean Irrigated Rice (FLAR) should be strengthened to address the yield gap issues by networking with national programmes.
It is acknowledged that donor-funded programmes in areas such as IPM and hybrid rice in Southeast Asia have been highly successful in reducing yield gaps and improving farmers' health and the quality of the environment.
It is recommended that the international donor community should continue to provide support to national public sector entities, international institutions and grower associations that are focusing on bridging the yield gap, for example, pilot programmes to establish and test tropical Ricecheck systems in selected sites, and strengthening national capacity to carry out pilot programmes for narrowing yield gaps.
It is recommended that the success of grower associations be recognized and organizations of farmer groups be encouraged to support research and development for their needs.
A viable and sustainable structure should be developed to deliver the required research and technology transfer options to bridge the yield gap.
Appropriate training for extension officers should be organized to equip them with skills in group facilitation as well as sound technical knowledge.
Extension officers should monitor the crop performance and yields over time, identify emerging problems (if any) and provide feedback to researchers with the aim of finding solutions through relevant research.
Disseminate successful management options among farmers and others through appropriate communication strategies designed for a wider impact, for example, large field demonstrations, messages, guidelines, decision support systems, timing for various operations, and warnings of pest outbreaks in print and on radio, television and the Internet.
Ensure the availability of inputs, credit, and other incentives necessary to facilitate farmer adoption of the recommended practices. This process provides an additional opportunity to involve agribusiness in providing inputs, services and technical support to farmers.
It is recommended that FAO collaborate with different stakeholders to develop region-specific recommendations and an action plan to address the yield gap.
It is recommended that national and international efforts be devoted to developing new varieties by broadening the genetic base and using modern tools such as biotechnology.
It is recommended that international and national institutions facilitate the exchange of prebreeding materials through networks.
To emphasize the importance of rice for world food security, the expert consultation supports the efforts of member countries and FAO to declare an International Year of Rice.

PRODUCTIVITY DECLINE

Introduction

Continued population growth necessitates the need for increased rice production to ensure food security in the developing world. Because the scope for further expansion of area under rice cultivation is limited, future growth in production will depend to a large extent on achieving higher yields. Yet the impressive yield growth achieved in the 1970s and 1980s slowed down considerably in the 1990s, below the population growth. Earlier research suggested that the recent slowdown in yield growth might, in part, be due to widespread yield and productivity declines in intensive irrigated rice-based cropping systems caused by deterioration of soil health and productivity.

It was because of these concerns that FAO convened a global expert consultation to deliberate on these issues and to suggest measures for effectively addressing the problem of rice productivity decline through national and international efforts. The recommendations of this consultation are presented below.

Identification of yield and productivity declines

The group discussed yield declines in three distinct systems, each with distinct causes. In irrigated African systems, for example, yield and productivity declines appear to result primarily from deterioration of infrastructure and management problems as opposed to degradation of the natural resource base. In upland production systems, continuous cultivation of rice is not feasible because of falling yields over time. These problems are important, and need to be addressed within an integrated national development programme that gives priority to the agricultural sector by improving its access to inputs and new technologies.

Within the intensive, continuously cropped irrigated systems that cover 28 million hectares and provide more than half the world's supply of rice, recent research indicates that yield and productivity declines are not as widespread as was previously believed. Such declines may not be an inevitable consequence of long-term intensive rice cropping. Nevertheless, yield and productivity declines have been documented under certain circumstances in certain locations.

The causes of the yield declines that have been documented vary from one location and ecosystem to another and are not always completely understood owing to the lack of measurements. In such cases, it is not easy to make appropriate recommendations. But several measures are warranted to help mitigate the yield and productivity declines that do occur due to degradation of the natural resource base in some intensive irrigated systems.

Definitions

The terms "yield decline" and "productivity decline" can be defined as follows:

Yield decline: a statistically significant reduction in yields over ten years at constant level of inputs and management practices, not due to climatic variability or changes in varieties (a shorter period of five years may be more appropriate for upland systems). This is usually more relevant for experiment station trials.
Productivity decline: a statistically significant reduction in total factor productivity (TFP) over five to ten years not due to climatic variability or changes in varieties (a shorter period of five years may be more appropriate for upland systems). This is usually more relevant for measurements in farmers' fields where input quantities change from year to year. TFP is a measure of the quantity of output relative to the quantity of all inputs used in production, and should be measured on a system basis.

Measures for reversing yield decline where it occurs

Many researchers and farmers are not adequately aware of the dangers of long-term negative phosphorus, potassium and micronutrient balances. Education and training of relevant stakeholders regarding the benefits of balanced nutrient applications will help alleviate the problems caused by excessive nutrient mining.
When cropping systems are so intense that the soil is kept under continuously submerged (anaerobic) conditions for long periods of time, yield and productivity declines may become serious issues. This phenomenon has been documented in several places around the world. While an increased intensity of cropping may be necessary to ensure food security, countries should be aware of the potential dangers of excessively intensive cropping and take adequate steps to alert farmers to these dangers.
The continued use of the same variety for an extended period, especially ones without substantial resistance to pests and diseases, is likely to lead to yield and productivity declines. This highlights the importance of breeding for continued resistance to pests and diseases and maintaining varietal diversity.
Declining organic matter content may be a causal factor of yield decline in the rice-wheat cropping system. This may warrant crop rotation and other measures that will preserve the optimal level of organic matter content, taking due account of the socio-economic conditions facing farmers.
Salinization and alkalinization processes may affect rice yields and soil quality. These may be remedied by alternative land and water use and/or breeding of tolerant varieties.
The development of herbicide-resistant weeds due to improper use of herbicides may affect the sustainability of rice cropping systems.

Recommendations for national and international actions in the medium term (2001-2005)

National programmes should:

embark on education campaigns to increase farmer awareness of the benefits of balanced fertilizer use;
remain cognizant of the dangers associated with overly intensive cropping;
continue to support breeding programmes to improve progressively yield potential and stability in the presence of abiotic and biotic stresses;
conduct fewer and more appropriate long-term experiments (in representative regions and ecosystems) with more detailed, interdisciplinary measurements;
select several pilot sites to monitor continuously yield and productivity trends. An emphasis on micro-level investigation (for example, state seed farms and farmers' fields) is suggested.

International programmes should:

support national programmes in the above endeavours and continue with ongoing cross-country network research on yield and productivity trends in major rice-based cropping systems.

Conclusions et recommandations de la Consultation d'experts sur les écarts de rendement et la baisse de productivité de la production rizicole

À l'issue de leurs délibérations, les experts ont formulé des définitions, des directives et des recommandations sur les écarts de rendement et la baisse de productivité de la production rizicole. Pour diminuer les écarts de rendement, les experts ont soumis 10 recommandations aux programmes nationaux et 14 recommandations aux organismes et instituts régionaux et internationaux. Les recommandations les plus importantes concernent la promotion de l'élaboration et de l'utilisation de mesures de gestion objectives pour aider les agriculteurs et les obtenteurs à atteindre les objectifs de rendement et de gestion pour un lieu donné, comme le modèle australien Ricecheck. Pour la baisse de productivité, les experts ont soumis cinq recommandations générales et six recommandations particulières aux instituts nationaux. Les experts ont également recommandé aux programmes internationaux d'appuyer les programmes nationaux dans leurs efforts et de poursuivre les recherches en cours du réseau interpays sur les tendances du rendement et de la productivité dans les principaux systèmes rizicoles.

Conclusiones y recomendaciones de la Consulta de expertos sobre el déficit de rendimiento y el descenso de la productividad en la producción de arroz

Los expertos participantes, tras el debate y las deliberaciones, presentaron definiciones, directrices y recomendaciones sobre el déficit de rendimiento y el descenso de la productividad en la producción de arroz. En cuanto a la reducción de los déficit de rendimiento, los expertos presentaron 10 recomendaciones para los programas nacionales y 14 recomendaciones para los organismos e instituciones regionales e internacionales. Las recomendaciones más importantes son la promoción del desarrollo y la aplicación de recomendaciones objetivas para la ordenación de los cultivos con el fin de facilitar que los agricultores y los productores cumplan los objetivos con respecto a la citada ordenación y a los rendimientos en un lugar determinado, como sucede con el modelo australiano Ricecheck.

En cuanto al descenso de la productividad, los expertos presentaron a las instituciones nacionales cinco recomendaciones generales y seis específicas. Asimismo, recomendaron que los programas internacionales apoyaran a los nacionales en los esfuerzos que éstos realizan y también que mantuvieran la red de investigaciones en distintos países sobre las tendencias de los rendimientos y la productividad en los principales sistemas de cultivo basados en el arroz.