EXPERT CONSULTATION ON YIELD GAP AND PRODUCTIVITY DECLINE IN RICE PRODUCTION,
Rome, Italy, 5-7 September 2000
YIELD GAP
Definition
Guidelines for Identification of Yield Gaps
Causes of Yield Gaps
Guidelines to Close Yield Gaps
Recommendations for National and International Action in Medium Term (5 Years)
PRODUCTIVITY DECLINE
Introduction
Identification of Yield and Productivity Declines
Definitions
Measures for Reversing Yield Decline Where it Occurs
Specific Recommendations for National and International Actions (2001-2005)
Twenty-seven rice experts from Australia, Brazil, Colombia, Egypt, India, Italy, Republic of Korea, Nigeria, the Philippines, the USA, and Venezuela, IRRI, WARDA, FAO/IAEA and FAO attended the Expert Consultation. The following are the conclusions and recommendations:
YIELD GAP
The potential
yield for a variety x environment combination is derived from modelling with
optimum growth conditions. There is the highest yield that can be used for breeding
higher yielding varieties.
Under practical field conditions, we can only achieve from 80% to 85% of the
potential yield for a given variety x environment combination. Thus we can define
the practical yield gaps 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 second gap is the difference between the mean yield of large plot demonstrations or top 10% 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% between attainable and economically exploitable yields depending on the ecosystem and country.
2. Guidelines for Identification of Yield Gaps
The research on yields derive mostly 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 set up on location where by the information on yield gaps can be updated on a regular basis.
Biophysical, socio-economic, technical/management, and institutional/policy factors cause the yield gaps.
Biophysical: climate, soil type, water availability, pest pressure, etc.
Socio-economic, institutional and/or policy: Farmers' resource level, education, skills, attitude, etc.; infrastructure; land tenure; credit and inputs supply;
Technical: varieties, resource use efficiency (water, soil, nutrients, seed quality, pests including weeds, harvest and post-harvest, etc.).
4. Guidelines to Close Yield Gaps
4.1.
Identify
the target group to change: farmers, socio-economic, institutional/infrastructure,
and/or policy support groups. Biophysical traits are difficult to change, but
varietal selection and crop management practices can be used to mitigate the
effect of biophysical constraints to a certain extent. If the factors involve
socio-economic, institutional and/or policy areas that are outside farmers'
control, then the efforts should be made to address these problems at the policy
level.
4.2.
Develop a checklist to identify and prioritize the technical constraints. A model checklist is provided below:
The rice field infrastructure
Rotation in cropping systems
Rice varieties
Seed quality
Time of sowing
Crop establishment
Crop protection: weeds, pests, diseases, IPM
- Nutrition: N and other nutrients, INM
Water management
Harvesting
Post-harvest management to reduce losses and to improve grain quality
4.3.
Identify the technology options from the above check list to address the critical constraints to narrow the yield gap.
Develop
objective crop management recommendations to assist farmers/growers to meet
crop management and yield targets for a given location. This can assist growers
to evaluate their own management performance, identify strengths and weaknesses,
and take action to improve management for subsequent crops, such as the Australian
Ricecheck system and similar models used in Egypt and Korea (see Annex).
4.4.
Develop
mechanisms to evaluate, refine and deliver the recommendations, in close collaboration
with farmers, e.g. government extension service, NGOs, voluntary organisations,
private sector agencies, farmer groups or grower associations.
4.5.
Use farmer
discussion groups to promote the adoption of the ricecheck recommendation systems
and specific technologies that require greater emphasis. Discussion groups provide
an opportunity to use the skills and experiences of farmers to reinforce and/or
modify the recommendations.
4.6.
Extension
officers require skills in group facilitation as well as sound technical knowledge.
4.7
Make available
inputs, credit, and other incentives necessary to facilitate farmer adoption
of recommended practices. There is an additional opportunity to involve agribusiness
to provide inputs, services and technical support to farmers
4.8.
The extension
staff should monitor the crop performance and yields over time, identify emerging
problems, if any, and feed them back to researchers to find solutions through
relevant research.
4.9.
Disseminate
successful management options, among farmers and others through appropriate
communication strategies for wider impact, e.g. large field demonstrations,
messages, guidelines, decision support systems, and timing for various operations,
and warnings of pest outbreaks, etc. in print media, radio and TV as well as
internet.
4.10.
Make sure that an effective research and extension infrastructure is available to address the problems and to provide technical support to farmers. This will strengthen the linkage between research, extension and farmers.
5. Recommendations for National and International Action in Medium Term (5 Years)
5.1.
Raise awareness
of yield gaps and factors causing yield gaps among all stakeholders (farmers,
extension staff, researchers, government decision-makers, etc.). For example,
FAO can organise dialogues with national governments to address the policy-related
issues responsible for yield gaps.
5.2.
The collaboration
among FAO, IRRI, WARDA, and CIAT/FLAR should be strengthened in order to address
the yield gap issues by networking with national programmes.
5.3.
It is greatly
acknowledged that donor-funded programmes, such as IPM and hybrid rice in South
East Asia, have been highly successful in reducing yield gaps and improving
farmers' health and environmental quality.
5.4.
It is recommended
that international donor communities continue to provide support to national
public sector entities, international institutions, and grower associations
that are focussed on bridging the yield gap, e.g. pilot programmes to establish
and test tropical ricecheck systems in selected sites, national capacity to
carry out pilot programmes for narrowing yield gaps.
5.5.
It is recommended
that the successes of grower associations be recognised and organisations of
farmer groups be encouraged to support R and D for their needs.
5.6.
Develop
a viable and sustainable structure to deliver the required research and technology
transfer options to bridge the yield gap.
5.7.
Appropriate
training should be organised to give extension officers skills in group facilitation
as well as sound technical knowledge.
5.8.
Extension
officers should monitor the crop performance and yields over time, identify
emerging problems ,if any, and feed them back to researchers to find solutions
through relevant research.
5.9.
Disseminate
successful management options, among farmers at large, through appropriate communication
strategies for wider impact, e.g. large field demonstrations, messages, guidelines,
decision support systems, and timing for various operations, and warnings of
pest outbreaks, etc. in print media, radio and TV as well as internet.
5.10.
Make available
inputs, credit, and other incentives necessary to facilitate farmer adoption
of recommended practices. There is an additional opportunity to involve agribusiness
to provide inputs, services and technical support to farmers.
5.11.
It is recommended
that FAO, in association with different stakeholders, come up with region-specific
recommendations and an action plan to address the yield gap.
5.12.
It is recommended
that national and international efforts be devoted to develop new varieties
by broadening the genetic base and using modern tools such as biotechnology
and other tools.
5.13.
It is recommended that international and national institutions facilitate the exchange of pre-breeding materials through networks.
5.14.
To emphasise the importance of rice for world food security, we support the efforts of Member Countries and FAO to declare an "INTERNATIONAL YEAR OF RICE".
PRODUCTIVITY DECLINE
Continued
population growth necessitates continued production growth to ensure food security
in the developing world. Because the expansion of area is limited, under current
market conditions, future growth in production will depend, to a large extent,
on 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 be partially
due to widespread yield and productivity declines in intensive irrigated rice-based
cropping systems on account of deterioration of the soil's health and productivity.
In view of these concerns, FAO convened a global expert consultation to deliberate
on these issues and to suggest measures for effectively addressing this problem
through national and international efforts. The recommendations of this consultation
are presented below.
2. Identification of Yield and Productivity Declines
2.1.
The group
discussed yield declines in three distinct systems, each with distinct causes.
In irrigated African systems, yield and productivity declines are primarily
caused by the 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 owing to the decrease in yields over a length
of time. These problems are important and need to be addressed, within an integrated
national development program that gives priority to the agricultural sector.
This can be implemented by improving access to inputs and new technologies.
2.2.
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 previously believed.
Such declines may not be an inevitable consequence of long-term intensive rice
cropping. However, yield and productivity declines have been documented under
certain circumstances in certain locations.
2.3.
The causes of the yield declines, which have been documented, vary from one location and ecosystem to another. Often, the causes are not completely understood due to the lack of appropriate measurements. In such cases, it is not easy to make appropriate recommendations. However, several measures are warranted to help mitigate the yield and productivity declines that do occur caused by degradation of the natural resource base in some intensive irrigated systems.
Yield decline: A statistically significant reduction occurs in yields over 10 years at constant level of inputs and management practices, not due to climatic variability or changes in varieties; a shorter period of 5 years may be more appropriate for upland systems. This is usually more relevant for experiment station trials.
Productivity decline: A statistically significant reduction occurs in the total factor productivity (TFP) over 5 to 10 years, not due to climatic variability or changes in varieties; a shorter period of 5 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.
4. Measures for Reversing Yield Decline Where it Occurs
4.1.
Firstly,
many researchers and farmers are not adequately aware of the dangers of long-term
negative P, K and micro-nutrient balances. Education and training of relevant
stakeholders, regarding the benefits of balanced nutrient applications, will
help alleviate the problems caused by excessive nutrient mining.
4.2.
Secondly,
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 of
these dangers.
4.3.
Thirdly,
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.
4.4.
Fourthly,
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.
4.5.
Fifthly,
salinization and alkalinization processes may affect rice yields and soil quality.
This may be remedied by alternative land and water use and/or breeding of tolerant
varieties.
4.6.
Sixthly, development of herbicide resistant weeds, caused by improper use of herbicides may affect the sustainability of rice cropping systems.
5. Specific Recommendations for National and International Actions (2001-2005)
National programs should:
Embark on education campaigns to increase farmers' awareness of the benefits of balanced fertilizer use.
Remain cognisant of the dangers associated with overly intensive cropping.
Continue to support breeding programmes to progressively improve 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 (e.g., state seed farms, and farmers' fields) is suggested.
International programs should:
Support national programs in the above endeavours and continue with ongoing cross-country network research on yield and productivity trends in major rice-based cropping systems.