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Theme 3: Ecological and Sustainable Management of Rice-based Production Systems
Irrigated rice systems account for 75% of global rice production, providing the staple food for about 2 billion people. Rainfed rice systems in lowlands and uplands, on the other hand, provide livelihoods for hundreds of millions of farmers and their families living in some of the poorest regions of the world. Theme 3 is all about accomplishing multiple goals of improving food security, incomes, and nutrition and doing it in a more environmentally friendly and sustainable manner—through innovations for more precise management of future rice-based farming systems. These production systems will be both more productive and more eco-efficient, but also more resilient to climatic extremes and other drivers of change.
Three millennia of continuous production of irrigated rice in Asia, either as a monocrop or in rotation with other crops, demonstrates the inherent sustainability of the system. This historic sustainability is now threatened, however, by recent rapid population growth that leads to a declining share of land, water, labor, and energy resources. Inefficient use or overuse of production inputs may also lead to pollution, environmental degradation, and declining ecosystem services. Nitrogen-use efficiency in most intensive rice systems remains below 40% and unbalanced nutrient applications are still common. By 2025, 15–20 million ha of irrigated rice will suffer some degree of water scarcity, which results from competing water uses and climate change, and requires rethinking of current management paradigms. In northwestern India, declining groundwater levels pose a serious threat to one of the world’s most important grain baskets. In fact, rice systems draw much of their ecological resilience from intensive water use (e.g., weed control, control of soil salinity and pH, heat avoidance through thermal cooling), and new solutions need to be found for water-scarce conditions.
In many areas, the ecological resilience of rice ecosystems and their capacity for natural control of rice pests are weakened by the overuse of pesticides and breakdown of rice host-plant resistance. Animal pests, diseases, and weeds are responsible for a 25–45% loss of rice production in tropical and subtropical Asia. Market-driven diversification of rice-based cropping systems, while offering potential for increasing farm income, also presents new challenges for sustainable management. If done wrong, it may lead to a decline in soil health and productivity. Overarching these issues are the threats of—and opportunities from—climate change. Besides increased temperatures, stresses such as flooding, drought, and salinity, which are widespread in rainfed environments, now encroach on irrigated environments as well.
In Latin America, irrigated rice monoculture is the most common system in the tropics, while monocropping and crop rotations are predominant in the southern temperate regions. Yield gaps are high throughout the region. In Africa, lowland rice is cultivated along an intensification gradient, ranging from practically undisturbed inland valleys to intensively cropped irrigation systems. Fertilizer use is generally very low, mainly because of high prices and poor distribution networks. Gaps between attainable and actual yields are high, even in input-intensive systems. Because most rice is grown under rainfed conditions, drought is a major determinant of yield, often in combination with phosphorus deficiency. Even in Asia, about half of the rice area is affected by drought, uncontrolled submergence, or salinity. Yields in these stressed environments are typically low, in the range of 1–2 tons per hectare, and poverty is extreme and widespread. Moreover, climate change is expected to exacerbate the frequency, severity, and extent of these stresses. In Asia, Africa, and Latin America, rice is also cultivated in upland ecosystems (about 40% of the rice-growing areas in sub-Saharan Africa and LAC). Uplands are extremely diverse and fragile, and deep poverty is found among upland farming communities where socioeconomic constraints hamper intensification and the development of more profitable farming systems.
There is still large scope for significant and sustainable increases in rice productivity globally through improved agronomic practices. Water-saving technologies such as safe alternate wetting and drying (AWD) and dry seeding not only offer hope for rice farmers affected by water scarcity but also can free up water from rice-growing areas for other economic or environmental purposes. The novel system of aerobic rice, in which rice is cultivated in nonpuddled and nonflooded soil just like wheat and maize, drastically reduces water requirements and allows cropping of rice where a lack of water has made this impossible till now. Site-specific nutrient management (SSNM) greatly increases the use efficiency of applied fertilizers and can increase yields, reduce losses to the environment, and increase the profitability of farming. Through the development of new machinery and resource-conserving technologies (RCT), principles and practices of conservation agriculture (CA), which hitherto have mostly been used in dryland crops, now have scope for application in both single-rice and diversified rice-based cropping systems. Landscape management by ecological engineering can increase ecological resilience against invasive pests such as brown planthoppers and thus reduce the need for application of pesticides. Regional strategies for the deployment of resistance genes against pests and diseases can increase the durability of varietal resistance. New rice varieties with increased tolerance of drought, submergence, and salinity are becoming available and targeted management technologies help exploit the genetic potential of these varieties in farmers’ fields. Emissions of greenhouse gases can be reduced by modified water and nutrient management, such as AWD and timely tillage and residue management. Altogether, new crop and resource management technologies offer tremendous scope for reducing yield gaps, increasing rice production, and protecting the environment, with positive benefits for both rice farmers and society at large.
In theme 3, we focus on further developing the scientific basis for so-called “component technologies” (such as AWD, SSNM, CA) and integrating them into holistic and pro-poor farming-system solutions. We will increase our understanding of crop-soil-water interactions through long-term field experiments established at “experimental platforms” in key rice ecologies. At these platforms, a range of rice-based cropping systems are established based on principles of ecological intensification (Box 11) and resource-conserving technologies, and they are geared toward the future in terms of major drivers of change. We will study interactions among animal pests, diseases, and weeds on the one hand and soil, nutrient, and water management on the other. At selected sites, we will study fluxes of energy, water, and greenhouse gases to determine the impact on global warming potential. Existing knowledge and new process-based insight will be used to design best-bet cropping systems for participatory on-farm testing and site-specific adaptation to local conditions.
New farm implements, machinery, and equipment to practice conservation agriculture are compared, tested, and improved. Farmer participation and the use of learning alliances among key stakeholders (farmers, extensionists, scientists, NGO agents, etc.) will ensure the inclusion and use of local and third-party knowledge and bring to the forefront gender issues and perspectives. Taking into account socioeconomic resource endowments and boundary constraints, whole-farm and cropping-system solutions will be pro-poor and adoptable.
In intensive rice production systems, we will focus on opportunities for, and challenges to, ecological intensification and crop diversification (e.g., rice-wheat/maize/pulses/potato). In major stress-prone environments (such as drought, submergence, and salinity), new varieties with increased tolerance will be incorporated into the cropping systems.
Across agroecosystems, we will develop management technologies that reduce emissions of greenhouse gases and design new cropping systems that are adapted to climate change. At the landscape level, we will apply principles of ecological engineering to manipulate landscape components such as bunds, dikes, and other noncropped areas, to increase biological diversity and increase resilience against pests and diseases.
Epidemiological research will be conducted on major rice pests and diseases by elucidating relationships among rice plants, diseases and their vectors, crop management practices, and the natural environment. In addition to experimentation, we will develop and use simulation modeling tools (for crops, water, and pest and disease epidemics) to scale-up site-specific experimental results, to assess the impacts of climate change and major drivers of change such as water scarcity, and to explore options of management interventions.
3.1 Future management systems for efficient rice monoculture
3.2 Resource-conserving technologies for diversified farming systems
3.3 Management innovations for poor farmers in rainfed and stress-prone areas
3.4 Increasing resilience to climate change and reducing global warming potential
In general, GRiSP CGIAR centers (IRRI, AfricaRice, and CIAT) focus on developing generic international and global/regional public goods, whereas regional, national, and local partners play a key role in adaptive research and diffusion/dissemination of technologies. Advanced research institutes and universities, especially from India, China, and Brazil, are frontier partners in the research on and development of new management technologies and the underlying science. By linking these partners with those in less-developed target countries, south-south technology transfer and adaptation of technologies are facilitated. Local adaptive research and dissemination/diffusion involve an array of public- and private-sector partners.
Theme 3 interacts closely with theme 6 and boundary partners for further uptake and widespread diffusion include formal public-sector extension agencies, NGOs (e.g., World Vision in Vietnam and CRS in Africa), civil society groups, farmer groups, irrigation system managers, and the private sector, such as fertilizer and agricultural equipment companies. Partnerships with leading institutions in developed and BRIC countries are also forged on advanced and upstream science and R&D topics such as simulation modeling, for which we partner with WUR in the Netherlands, CSIRO in Australia, NIAES in Japan, and Cirad in France. Innovation partnerships on participatory and adaptive research and development will ensure that indigenous and local knowledge are captured and that gender-specific issues are explored in the design of new management technologies. Cirad co-leads a number of product developments, especially on crop modeling, land and water management, and upland production systems.
Through creating and fostering innovative public-/private-sector partnerships in key regions, work under this theme will boost the deployment of well-adapted germplasm × management solutions for the world’s primary irrigated and rainfed rice-based cropping systems, including new ones for the future, such as resource-conserving technologies for conservation agriculture.
Products from this theme will reach farmers at an accelerated pace through regional networks for crop and resource management research and delivery, such as IRRC, CURE, and CSISA in Asia; IVC and the new Task Force Mechanism led by AfricaRice in Africa; and FLAR in Latin America. These networks help to channel management innovations into adaptive efforts by NARES, NGOs, agricultural development initiatives, and extension efforts. A concrete example of an impact pathway is given for the technology of site-specific nutrient management in PL 3.1. Theme 3 activities will be closely linked with variety development in GRiSP theme 2 to ensure that the performance of new varieties is optimized for appropriate growing conditions. Theme 3 products mainly feed into GRiSP Theme 6 for accelerated and large-scale delivery. This will also involve engagement with other CGIAR research programs and centers working in the target regions.