More crop per drop
Saturday, 4 August 2007
Sarah Carriger and Domitille Vallee
The challenge for rice cultivation in the next 50 years is to feed more people while keeping prices low to benefit poor rice consumers and reducing production costs to benefit poor growers. At the same time, water scarcity, drought, flooding, and salinity increasingly threaten the productivity of rice-based systems.
How can we meet this challenge? Some solutions exist; others require more investment in research. No single solution will fit all situations. Solutions need to be evaluated based on impacts on the poor, on the environment, and on the often unrecognized ecosystem services that rice landscapes provide.
Rice systems are also social systems. In many cases, they are based on hundreds, even thousands, of years of tradition. Unless solutions are designed and implemented with the active participation and support of the rice-growing communities, they will not be successful.
Rice is currently the staple food of around 3 billion people, and demand is expected to continue to grow as population increases-by 1 per cent annually until 2025 in Asia and
by o.6-o.9 per cent worldwide until 2050. While the bulk of the world's rice is grown and consumed in Asia, changing dietary preferences are also affecting rice consumption in other parts of the world. Rice demand is increasing the most rapidly in West and Central Africa-by 6% each year.
So, where will the rice come from to feed these additional rice consumers? To avoid destruction of natural ecosystems, increasing yields on existing crop lands are the best option. This includes both irrigated and rainfed land, although most of the additional production will come from irrigated lowlands, which already supply 75% of the world's rice.
In some major rice-producing countries, such as Bangladesh, the Philippines, and Thailand, there is still a large gap between actual and potential yield. In these countries, water and crop management technologies hold the most immediate promise. In other countries-namely, China, Japan, and Korea-the yield gap is already closing, and further yield increases are likely to come from genetic improvement. This means more research and investment in breeding programs. In irrigated lowlands with ample water supply, the development of hybrid rice has the potential to increase yield by 5-15%.
Many poor people spend 20-40% of their income on rice alone. The reduction in the price of rice-from US$1,ooo per tonne in 196o to an average of around $250 over the past 5 years-may have done more to benefit Asia's poor than any other single factor. Keeping rice prices low remains in the best interests of poverty reduction in areas where rice is the staple food.
On the other hand, low prices can hurt poor rice growers. Most of the world's rice farming takes place on small family-owned farms, with average sizes varying by country from 0.5 to 4 hectares. And, in many areas, rice farming is the main source of employment. Increasing yields and reducing production costs are the first steps for many families to escape poverty. Rice-related policies, breeding programs, and water and land management technologies and practices need to take into account possible impacts-positive and negative-on the poor who depend on rice as a source of food and income.
Interventions affect men and women differently because the division of labor in rice cultivation is, in most countries, along gender lines. This means, for example, that in areas where women do most of the transplanting, changing to direct seeding can mean either an additional burden or a source of employment for women, depending on whether or not they are paid for their labour.
Purely technical approaches will not work. Any solutions need to take into account that, in many communities, rice cultivation is at heart of social and religious life.
Over the coming decades, farmers, policymakers, and researchers alike will need to adapt to several threats to rice production.
In the next 25 years, 15-20 million hectares of irrigated rice land are projected to suffer from some degree of water scarcity-particularly wet-season irrigated rice in parts of China, India, and Pakistan. Even in areas where water is abundant, hotspots of water scarcity exist. Economic water scarcity, where lack of financing presents harnessing water resources for productive use, limits cultivation of the 22 million hectares of dry-season irrigated rice in South and Southeast Asia.
Between a quarter and a third of the world's tapped freshwater resources are already used to irrigate rice. Pressure to reallocate water from irrigated agriculture to cities and industries is already affecting rice cultivation in many parts of the world. This type of transfer can be accomplished without a drop in rice production, but it requires a combination of supportive policies and the introduction of improved practices and technologies.
Increasing water scarcity may also force a shift in rice production to more water-abundant delta areas. And, in water-short areas, aerobic rice production-growing rice without a standing water layer-and irrigation regimes of alternate wetting and drying may come to predominate alongside a shift to nonrice dryland crops such as maize.
Droughts, flooding, and salinity are all current threats to production particularly in rainfed areas, and they may increase in severity under climate change.
Frequent droughts afflict approximately 25 million hectares of rainfed rice, primarily in eastern India, northeastern Thailand, Lao PDR, and Central and West Africa.
Salinity affects another 9-12 million hectares-mostly in India, but also in Bangladesh, Thailand, Vietnam, Indonesia, and Myanmar. Salinity is a threat in deltas where sea water intrudes inland and in some aerobic rice production systems.
Some 11 million hectares of both irrigated and rainfed rice are prone to flooding. Even though rice is adapted to waterlogging, most varieties can survive complete submergence for only 3 to 4 days. The recent development by researchers at the International Rice Research Institute of submergence-tolerant rice, which can withstand 10-14 days of submergence with up to three times the yield of nontolerant varieties, offers hope to farmers in flood-prone areas.
In areas prone to drought, salinity, and floods, the combination of improved varieties and specific management packages has the potential to increase on-farm yields by 50-100% in the coming 10 years, provided that investment in research and extension is intensified.
Groundwater development most of it private and largely unregulated-has enabled small rice growers in many areas to prosper, but unsustainable pumping threatens the viability of these production systems. For example, in the North China Plain, water tables are dropping by 1-3 meters per year and in the northwest IndoGangetic Plain they are dropping by 0.5-0.7 metre per year.
Declining water tables due to overpumping threaten not only agricultural productivity but also human health, since many communities are dependent on groundwater for their drinking water. In Bangladesh and parts of India, falling water tables have been linked to contamination of groundwater with naturally occurring arsenic and fluoride.
Climate change may affect rice productivity in several ways. It is expected to increase the frequency of droughts and flooding, and to increase temperatures, which will have a negative impact on yields. Simulations find that for every 1 degree rise in mean temperature, there is a corresponding 7% decline in rice yield. Developing rice varieties that are less sensitive to higher temperatures is the only way to cope with rising temperatures.
Of the potential threats, water scarcity and increasing competition for water in irrigated rice systems are perhaps the most pressing in terms of potential impact on overall production levels.
— Rice Today
The challenge for rice cultivation in the next 50 years is to feed more people while keeping prices low to benefit poor rice consumers and reducing production costs to benefit poor growers. At the same time, water scarcity, drought, flooding, and salinity increasingly threaten the productivity of rice-based systems.
How can we meet this challenge? Some solutions exist; others require more investment in research. No single solution will fit all situations. Solutions need to be evaluated based on impacts on the poor, on the environment, and on the often unrecognized ecosystem services that rice landscapes provide.
Rice systems are also social systems. In many cases, they are based on hundreds, even thousands, of years of tradition. Unless solutions are designed and implemented with the active participation and support of the rice-growing communities, they will not be successful.
Rice is currently the staple food of around 3 billion people, and demand is expected to continue to grow as population increases-by 1 per cent annually until 2025 in Asia and
by o.6-o.9 per cent worldwide until 2050. While the bulk of the world's rice is grown and consumed in Asia, changing dietary preferences are also affecting rice consumption in other parts of the world. Rice demand is increasing the most rapidly in West and Central Africa-by 6% each year.
So, where will the rice come from to feed these additional rice consumers? To avoid destruction of natural ecosystems, increasing yields on existing crop lands are the best option. This includes both irrigated and rainfed land, although most of the additional production will come from irrigated lowlands, which already supply 75% of the world's rice.
In some major rice-producing countries, such as Bangladesh, the Philippines, and Thailand, there is still a large gap between actual and potential yield. In these countries, water and crop management technologies hold the most immediate promise. In other countries-namely, China, Japan, and Korea-the yield gap is already closing, and further yield increases are likely to come from genetic improvement. This means more research and investment in breeding programs. In irrigated lowlands with ample water supply, the development of hybrid rice has the potential to increase yield by 5-15%.
Many poor people spend 20-40% of their income on rice alone. The reduction in the price of rice-from US$1,ooo per tonne in 196o to an average of around $250 over the past 5 years-may have done more to benefit Asia's poor than any other single factor. Keeping rice prices low remains in the best interests of poverty reduction in areas where rice is the staple food.
On the other hand, low prices can hurt poor rice growers. Most of the world's rice farming takes place on small family-owned farms, with average sizes varying by country from 0.5 to 4 hectares. And, in many areas, rice farming is the main source of employment. Increasing yields and reducing production costs are the first steps for many families to escape poverty. Rice-related policies, breeding programs, and water and land management technologies and practices need to take into account possible impacts-positive and negative-on the poor who depend on rice as a source of food and income.
Interventions affect men and women differently because the division of labor in rice cultivation is, in most countries, along gender lines. This means, for example, that in areas where women do most of the transplanting, changing to direct seeding can mean either an additional burden or a source of employment for women, depending on whether or not they are paid for their labour.
Purely technical approaches will not work. Any solutions need to take into account that, in many communities, rice cultivation is at heart of social and religious life.
Over the coming decades, farmers, policymakers, and researchers alike will need to adapt to several threats to rice production.
In the next 25 years, 15-20 million hectares of irrigated rice land are projected to suffer from some degree of water scarcity-particularly wet-season irrigated rice in parts of China, India, and Pakistan. Even in areas where water is abundant, hotspots of water scarcity exist. Economic water scarcity, where lack of financing presents harnessing water resources for productive use, limits cultivation of the 22 million hectares of dry-season irrigated rice in South and Southeast Asia.
Between a quarter and a third of the world's tapped freshwater resources are already used to irrigate rice. Pressure to reallocate water from irrigated agriculture to cities and industries is already affecting rice cultivation in many parts of the world. This type of transfer can be accomplished without a drop in rice production, but it requires a combination of supportive policies and the introduction of improved practices and technologies.
Increasing water scarcity may also force a shift in rice production to more water-abundant delta areas. And, in water-short areas, aerobic rice production-growing rice without a standing water layer-and irrigation regimes of alternate wetting and drying may come to predominate alongside a shift to nonrice dryland crops such as maize.
Droughts, flooding, and salinity are all current threats to production particularly in rainfed areas, and they may increase in severity under climate change.
Frequent droughts afflict approximately 25 million hectares of rainfed rice, primarily in eastern India, northeastern Thailand, Lao PDR, and Central and West Africa.
Salinity affects another 9-12 million hectares-mostly in India, but also in Bangladesh, Thailand, Vietnam, Indonesia, and Myanmar. Salinity is a threat in deltas where sea water intrudes inland and in some aerobic rice production systems.
Some 11 million hectares of both irrigated and rainfed rice are prone to flooding. Even though rice is adapted to waterlogging, most varieties can survive complete submergence for only 3 to 4 days. The recent development by researchers at the International Rice Research Institute of submergence-tolerant rice, which can withstand 10-14 days of submergence with up to three times the yield of nontolerant varieties, offers hope to farmers in flood-prone areas.
In areas prone to drought, salinity, and floods, the combination of improved varieties and specific management packages has the potential to increase on-farm yields by 50-100% in the coming 10 years, provided that investment in research and extension is intensified.
Groundwater development most of it private and largely unregulated-has enabled small rice growers in many areas to prosper, but unsustainable pumping threatens the viability of these production systems. For example, in the North China Plain, water tables are dropping by 1-3 meters per year and in the northwest IndoGangetic Plain they are dropping by 0.5-0.7 metre per year.
Declining water tables due to overpumping threaten not only agricultural productivity but also human health, since many communities are dependent on groundwater for their drinking water. In Bangladesh and parts of India, falling water tables have been linked to contamination of groundwater with naturally occurring arsenic and fluoride.
Climate change may affect rice productivity in several ways. It is expected to increase the frequency of droughts and flooding, and to increase temperatures, which will have a negative impact on yields. Simulations find that for every 1 degree rise in mean temperature, there is a corresponding 7% decline in rice yield. Developing rice varieties that are less sensitive to higher temperatures is the only way to cope with rising temperatures.
Of the potential threats, water scarcity and increasing competition for water in irrigated rice systems are perhaps the most pressing in terms of potential impact on overall production levels.
— Rice Today