Abstract
This paper explores some of the links between agroecosystem biodiversity, productivity and sustainability and the broader ends they serve -- sustainable food security, reduced poverty, improved public health, and conservation of natural biological diversity. In doing so, it first discusses alternative interpretations of biodiversity and sustainability, and then explores two ways to foster diversity within agroecosystems.

Agroecosystem biodiversity involves crop genetic diversity, crop species spatial and temporal diversity, natural biological diversity within agroecosystems, and the indirect effects of agroecosystems on natural biological diversity. (That is, productive systems in one area can indirectly foster natural biological diversity in another area by making cultivation less necessary.) It often is claimed that agroecosystem biodiversity improves system sustainability. This claim is difficult to assess, given the vast number of ways in which sustainability is interpreted. Sustainability would be a more meaningful objective if we could measure it. Unfortunately, most indicators of sustainability are narrowly driven by definitions, leading to arguments that are circular and to conclusions that ignore the fallacy of scale.

A classic example of the fallacy of scale can be found in South Asia's Green Revolution (GR), which often has been criticized as unsustainable. At the farm household level, GR technologies may foster low species diversity, reliance on external inputs, environmental pollution, and degradation of soil and water resources. However, at higher levels of analysis, they have been found to be associated with faster economic growth, higher incomes through employment generation, improved income distribution, reduced rates of population growth, and (not least) the saving of an estimated 40 million ha of land from the plow -- or the woodcutter's axe. Resource degradation in GR areas may be a cost of defusing threats to resource quality and natural diversity in fragile, marginal or forested areas. Researchers and farmers must work together to reduce this cost.

If agroecosystem diversity fosters system productivity, stability, sustainability, and improved environmental quality, then how can diversity be increased? One approach is diversity by design -- the conscious fashioning of more diverse agroecosystems, intended for widespread adoption by farming communities. This process includes participatory research on indigenous technical knowledge, with a view to extrapolating such knowledge to suitable areas. Unfortunately, research on diversity by design typically has not lead to widespread farmer adoption.

Another approach is demand-led diversification -- the process whereby higher incomes and reduced poverty generated by more productive agricultural practices shift the structure of food demand towards a more diverse array of products, among them fruits, vegetables and animal products. Farmers follow market signals and diversify their farming systems. Demand-led diversification leads to more biologically diverse agroecosystems at the regional level, but may or may not ensure increased biodiversity at the plot or farm level. It is argued that attainment of the overarching goals of sustainable food security, reduced poverty, improved public health, and conservation of natural biological diversity requires a mixed strategy that embraces sustainable productivity improvement in favored areas, sustainable productivity improvement in marginal, fragile areas, and sustainable management of market-led diversification processes. Sustainability is not enough -- productivity must increase as well.

Our common goals
There are a number of reasons for fostering diversity in agroecosystems. More diverse systems can take better advantage of ecological niches. Those species best adapted to different stresses (waterlogging, soil acidity, shading, drought, etc.) can be carefully positioned where they have a comparative advantage (Chambers, 1990). In addition, greater system diversity can improve stability and resilience. Diverse agroecosystems offers multiple pathways for energy and nutrient cycling; consequently system productivity is not held hostage to the performance vagaries of any particular species (Carroll, Vandermeer and Rosset, 1990). When properly designed, more diverse systems also can reduce problems associated with pests, diseases and weeds (Edwards, 1987) and can decrease reliance on external inputs (Gliessman, Garcia and Amador, 1981). Finally, more diverse systems may be associated with in-situ conservation of foodgrain land races and folk varieties (e.g., Smale et al., 1991).

However, the above examples suggest that agroecosystem biodiversity is not an end in itself. Rather, it is a means of achieving other ends -- productivity, stability, resilience, improved environmental quality, and the conservation of crop genetic diversity. In turn, and on a broader scale, these are but part of a larger set of societal goals -- sustainable food security, reduced poverty, and improved public health. Thus, agroecosystem biodiversity is often prized to the extent that it contributes to the attainment of these overarching goals.

Societies also value natural biological diversity in the broader sense. People are concerned about the possible extinction of species, partly because of their potential future benefits, partly because of the role they play in ecological balances, and partly because people simply place a value in their continued existence, regardless of possible future human benefits. These "option" or "existence" values are immensely important though exceedingly difficult to quantify (Serageldin and Steer, 1994; Bishop, 1978).

Agroecosystem biodiversity is linked in complex ways with system sustainability and productivity. These, in turn, are linked in complex ways with natural biological diversity. The objective of this paper is to explore some of these links, in the overall context of our common goals -- sustainable food security, reduced poverty, improved public health, and greater natural biological diversity.

Kinds of diversity
The notion of agroecosystem biodiversity can be understood in several different ways:

Crop genetic diversity. This embraces such factors as varietal concentration; pace of varietal change over time; genetic similarity among major cultivars; the conservation and pyramiding of favorable genes in breeders' varieties; the conservation and use of important genes present in folk varieties, land races and wild relatives; and opportunities for expanding crop genetic diversity through wide crosses and biotechnology (Smale, 1995).

Crop species diversity over space. This refers to the extent and complexity of mixed cropping, intercropping, relay cropping and agroforestry practices, usually at the plot level. Spatial species diversity may be exceedingly narrow (e.g., a Javanese sawah monocropped rice field) or exceedingly broad (e.g., a Javanese pekarangan home garden featuring simultaneous cultivation of fruit trees, banana plants, coffee, spices, and palawija food crops such as maize, cassava and soybean) (Charoenwatana and Rambo, 1988). It should be clear from the above examples that plots with low species diversity and high species diversity often are found within the same farming system.

Crop species diversity over time. This refers to the extent and complexity of annual or longer-term relay cropping or rotations. Temporal species diversity may be narrow (e.g., one maize monocrop crop per year, every year); broad within a year (e.g., an annual sequence of multiple cropping involving cereals, legumes and horticultural crops); or broad over several years (e.g., rice - potato - wheat patterns, broken every few years by a sugar cane crop, as found in parts of the South Asian Indo-Gangetic Plains) (Harrington et al., 1992). Crop species diversity over space and over time are not necessarily related.

Agroecosystem biodiversity through crop-livestock interactions. The presence of livestock in a system tends to greatly enhance the value of non-crop components of agroecosystems (crop residues, grazing lands, forest resources) and typically features nutrient cycling between rangeland and crop land, thus fostering improved productivity and sustainability of cropping systems and a higher potential for spatial and temporal crop species diversity (Powell and Williams, 1993).

Natural biodiversity within agroecosystems . More diverse agroecosystems—particularly those with greater spatial diversity and those with trees—may provide habitat for a wider array of flora and fauna, including microorganisms as well as wildlife.

Natural biodiversity as indirectly affected by agroecosystems. Highly productive agroecosystems can indirectly foster natural biodiversity by making it unnecessary to farm marginal or fragile areas, or to clear new forest areas for agriculture. Natural biodiversity in subtropical and tropical countries often is associated with the extent and quality of forested area (Pieri et al., 1995). These indirect links between agroecosystem productivity and sustainability and the conservation of habitat for natural biodiversity is a major theme in this paper.

Efforts to foster biodiversity in agroecosystems can focus on any of the above. Opportunities for broadening system diversity may be achieved by increasing crop genetic diversity, expanding crop species diversity over space and over time, fostering crop-livestock interactions, or improving productivity in favored agricultural areas to enable the protection of biologically diverse fragile, marginal or forested areas from agricultural uses.

What are the links between the introduction of more sustainable agroecosystems on the one hand, and the preservation of agroecosystem biodiversity (and natural biodiversity) on the other? The answer to this question depends on what is meant by "sustainability."

Top

Sustainability in perspective³
Issues of sustainability are commanding more attention from agricultural scientists, but only in part because they are thought to be closely linked to issues of biological diversity. Few themes can match "sustainability" for the broad range of questions to which it relates and (as a consequence) the sense of perplexity that it all too often engenders. The notion of sustainability encompasses population growth and pollution, deforestation and land degradation, agroecology and energy cycling, erosion and intergenerational equity, not to mention food security, global warming and the ultimate fate of humankind. It is a formidable topic.

Considerable effort has been expended in defining and interpreting the notion of sustainability. Although the definition suggested by the CGIAR⁴ has drawn widespread support, that support is not unanimous. There are a number of well-defined alternatives, including some that rather narrowly emphasize agroecosystem diversity and resilience (Conway, 1986) and others that stress the ethical duty of mankind to serve as steward of natural resources for the benefit of future generations (Batie, 1989). Still others emphasize the global nature of food security and resource quality questions, given opportunities for trade (Crosson, 1992). Most definitional differences stem from the diverse answers given to the fundamental question, "What do we wish to sustain?".

Sustainability would be a more meaningful objective if we could measure it. Many scientists agree that the ability to quantify sustainability is fundamental to making the concept useful (Hildebrand, 1989). Unfortunately little progress has been made in this regard, despite considerable work on developing sets of land quality indicators (e.g., Pieri et al., 1995) or on constructing a unique indicator that encompasses the various consequences of using a particular agricultural technology (near-term on-site productivity, longer-term on-site productivity, off-site costs and benefits, environmental costs and benefits) (e.g., Harrington, 1994).

Most commonly, indicators of sustainability are narrowly driven by definitions. This often leads to arguments that are merely circular. For example:

If agroecosystem sustainability is defined in terms of zero external input use, then any technical change leading to reduced external input use can be said to foster sustainability.

If agroecosystem sustainability is defined in terms of low levels of environmental pollution, then any technical change leading to less environmental pollution can be said to foster sustainability.

If agroecosystem sustainability is defined in terms of high agroecosystem biodiversity, then any technical change leading to higher agroecosystem biodiversity can be said to foster sustainability.

If agroecosystem sustainability is defined in terms of local self-reliance in agricultural production (i.e., avoidance of international markets), then any technical change leading to greater local self-reliance can be said to foster sustainability.

All of these definitions, and their corresponding indicators, are inadequate -- even when combined. They all emphasize the plot or farm community level of analysis, ignoring higher levels. That is, they succumb to what may be termed the "fallacy of scale": what appears to be unsustainable at one level of analysis may be a strong element in favor of sustainability at a higher level of analysis. Researchers and policy makers must take explicit account of possible fallacies of scale, and alternative levels of analysis, when they engage in the design of diverse, sustainable systems.

Top

An example -- the Green Revolution
An example may clarify the phrase fallacy of scale. Green Revolution technologies for rice and wheat in South Asia often have been criticized as being unsustainable (Bramble, 1989; Pingali and Rosegrant, 1994). At the level of the agroecosystem, these technologies may feature low species diversity ⁵, high reliance on external inputs and energy sources, environmental pollution from pesticides and fertilizers that negatively affect public health, and degradation of soil and water resources devoted to agriculture (Byerlee and Siddiq, 1994).

However, at higher levels of analysis, the widespread diffusion of Green Revolution technologies in parts of South Asia has been associated with accelerated economic development in Bangladesh (Allaudin and Tisdell, 1991); higher incomes through employment generation in Uttar Pradesh (Sharma and Poleman, 1994); improvements in income distribution in Pakistan (Renkow, 1994); reduced rates of population growth in Green Revolution areas of India (Vosti, 1994) -- and, not least, the saving of approximately 40 million ha from the plow (or the woodcutter's axe) in India alone (Borlaug, 1996). That is, in the absence of Green Revolution technologies, another 40 million ha of rice and wheat area would have been needed to meet human demands for food.

Of course, there wasn't another 40 million ha of land in India to devote to agriculture. Still, the Green Revolution undoubtedly played an immense role -- a role that is almost entirely unrecognized -- in reducing pressures to cultivate biologically diverse fragile, marginal or forested areas. By the same token, in the absence of the Green Revolution, food prices would have been higher, employment growth (especially off-farm employment) would have been slower, poverty would be more widespread, and population growth would have been more rapid -- exacerbating the threat to natural biological diversity over the coming decades.

So, in a very real sense, resource degradation and environmental pollution in favored Green Revolution areas has been (at a higher level of analysis) a cost associated with the defusing of longer-term threats to resource quality and natural biological diversity in biologically diverse fragile, marginal or forested areas.

Researchers and farmers must work together to reduce this cost. Plot-level threats to sustainability in Green Revolution areas must be addressed. Fortunately, it appears that much of the resource quality damage in these areas is reversible (Fujisaka, Harrington and Hobbs, 1994). The challenge for the future is to generate a "doubly green revolution" (Lele, 1995) -- one that maintains the powerful and favorable indirect consequences of highly productive agricultural technology, while improving resource quality, and reducing pollution in these favored areas. Sustainability is not enough - productivity must increase as well.

Top

Diversity by design
This paper contends that greater agroecosystem biodiversity -- particularly crop genetic diversity and spatial and temporal species diversity -- often can help achieve sustainable improvements in agricultural system productivity. In addition, it contends that sustainable improvements in productivity can help achieve sustainable food security, while alleviating poverty and helping conserve natural biological diversity (by reducing the need to expand agriculture into new and biologically diverse areas).

How, then, does one go about fostering the widespread use of more biologically diverse agroecosystems? There are at least two ways:

Diversity by design -- Researchers and farmers collaborate in the conscious design of more biologically diverse agroecosystems, which then are taken up on a large scale by farming communities. This process includes participatory research on indigenous technical knowledge about system diversity, with a view to extrapolating such knowledge to comparable areas.

Demand-led diversification -- Higher incomes and reduced poverty generated by more productive agricultural practices shift the structure of food demand towards a more diverse array of products, among them fruits, vegetables and animal products. Farmers follow market signals and diversify their farming systems.

The path of "diversity by design" is a direct one. It is the path taken by cropping systems and farming systems research (FSR). Certainly, the central objective of such research in Asia was to diversify cropping patterns by introducing a second non-rice crop into rice-based systems (IRRI, 1982). The opportunity to do this, of course, was a consequence of the introduction of short-duration, non-photoperiod sensitive rice varieties.

In Africa, the emphasis has been less on system intensification and more on reconciling food security and system sustainability requirements, in the context of biotic and abiotic stresses affecting crop production and widespread labor migration (e.g., Drinkwater and McEwan, 1994; Holden, 1993). Even in Africa, however, diversity has been a major theme in FSR. "Diversity by design" also has been characteristic of research on agroecology (Altieri, 1987; Harwood, 1988).

The lessons learned from FSR and from research on agroecology have been exceedingly valuable. They have vastly improved researchers' interest in and capacity to work with farmers in understanding and improving farming systems. However, these lessons have had more impact more on research management and style than in farmers' fields. They have not led to the expected widespread adoption by farmers of more diverse, productivity-enhancing resource-conserving agricultural systems (Shinawatra, 1994; Grafton, Walters and Bertelson, 1990; Tripp et al., 1991). Moreover, farmer adoption of new technology that can be attributed to investments in FSR has been concentrated in crop component technology, particularly varietal change (Tripp, 1991).

Work is urgently needed to improve the effectiveness of research (measured in terms of widespread adoption) aimed designing biologically diverse, productive and sustainable agroecosystems. Until then, the path of "diversity by design", on its own, seems unlikely to lead to the attainment of our common goals.

Top

Demand-led diversification
In contrast, the path of "demand-led diversification" is relatively indirect, but nonetheless already has led to widespread changes in farming systems, particularly in Asia. Higher incomes and reduced poverty generated by more productive agricultural practices (in the case of Asia, through new rice and wheat technology) have indeed led to a shift in the structure of food demand. Consumers have reduced their per capita intake of basic grains in favor of a more balanced diet with featuring fruits, vegetables and animal products. Farmers have followed market signals and have diversified their farming systems accordingly (Schuh and Barghouti, 1987; Barghouti, Timmer and Siegel, 1990). Spatial and temporal species diversity have increased -- though not necessarily at the plot level.

A classic example of this process is described for Indonesia by Roche (1988). Increased rice productivity in favored lowland areas expanded the supply of rice and reduced its price. Marginal rice areas (often on hillsides) became unprofitable and farmers in these areas ceased producing rice. However, higher incomes in both rural and urban areas (in large part due to improved productivity of rice and its consequent lower price) shifted the structure of demand for food towards fruits and vegetables. As a consequence, rice fields in hillside areas, e.g. of East Java, were converted to perennial fruit trees (especially papaya). This process was not entirely attributable to improved rice productivity, of course, as improvements in market infrastructure also were important.

This same process is evident in other areas where new technology has increased the productivity of basic grain production, e.g., the Indian Punjab (Singh, 1992).

In contrast, stagnating grain (in this case maize) productivity in Southern Africa has led to a continued food security crisis, expansion of maize cultivation into areas hitherto reserved for wildlife (Waddington et al., 1994), and a relative absence of market signals that would induce farmers to diversify their farms into cash crops. It's no coincidence that "diversification out of grain production" is not high on the Southern Africa research and policy agenda.

Success in demand-led diversification is sensitive to the policy environment. It has been argued by Barghouti, Timmer and Siegel (1990) that the following are needed:

An overall policy environment that encourages more flexible and broader cropping systems rather than commodity-support programs;

Laws and institutions that facilitate efficient marketing by establishing grades and standards for different commodities and developing and distributing farm inputs;

Public investment in physical and social infrastructure, communications, and information systems;

A rural financial system that mobilizes rural savings, makes credit available to traders, and diversifies the rural economy; and

Rural training and education systems to help prepare rural people for non-agricultural jobs.

Demand-led diversification will lead to more biologically diverse agroecosystems at the aggregate (e.g., regional) level, but may or may not ensure increased biodiversity at the plot or farm level. Moreover, plot-level trends in resource quality, external input use and environmental pollution may increase or decrease, in accord with the practices adopted as farmers learn to manage a new set of enterprises.

The path of "demand-led diversification", on its own, also may not to lead to the attainment of our common goals.

Top

Complementarity and competition
Attainment of the overarching goals of sustainable food security, reduced poverty, improved public health, and conservation of natural biological diversity requires the widespread use of more productive, stable, resilient agroecosystems, and the conservation of crop genetic diversity. This will require:

1. An emphasis on sustainable productivity improvement in favored areas -- to reduce the pressure to cultivate biologically diverse areas unsuited to agriculture, and to foster "demand-led diversification." However, this must be done in ways that conserve soil, water and genetic resources and reduce environmental pollution within these favored areas -- a doubly green revolution.

Agricultural research and development (featuring roles for scientists, extension workers, farmers and policymakers) can help through:

cereal varieties that are more tolerant to biotic and abiotic stress and that are more nutrient use efficient,

productivity-enhancing resource-conserving crop management practices, e.g., IPM, reduced tillage, use of green manure cover crops, etc.;

more effective "diversity by design" -- widespread adoption of new cropping patterns, farming systems and land management systems (featuring staple cereals) that capitalize on the advantages of system diversity to sustainably improve productivity.

2. An emphasis on sustainable productivity improvement in marginal, fragile areas -- acknowledging that the pressure to cultivate biologically diverse areas unsuited to agriculture can be reduced, but not eliminated. Again, varieties, crop management practices, cropping patterns, farming systems and land management systems can offer leverage points.

3. An emphasis on sustainable management of "demand-led diversification" -- The introduction of fruit and vegetable crops may either exacerbate or ameliorate problems of erosion, soil fertility loss, water-induced land degradation, external input dependence, or environmental pollution. A greater temporal and spatial diversity of enterprises in this case does not necessarily imply improved sustainability. As "demand-led diversification" takes hold, it again is up to stakeholders in agricultural research and development (scientists, extension workers, farmers and policymakers) to foster sustainable management strategies.

In the end, it is not a case of competition, but rather of complementarity. It is not a case of "Green Revolution" vs. "alternative agriculture," or "diversity by design" vs. "demand-led diversification." We must use all of the tools at our disposal -- following all promising paths -- to reach our common goals.

Top

Bibliography

Alauddin, M. and Tisdell, C. The Green Revolution and Economic Development, New York:St. Martin's Press, 1991.pp. xxiii + 322

Altieri, M.A., Norgaard, R.B., Hecht, S.B., Farrell, J.G., and Liebman, M. Agroecology The Scientific Basis of Alternative Agriculture, Boulder:Westview Press, 1987.pp. xviii + 227

Barghouti, S., Timmer, C., and Siegel, P. Rural Diversification: Lessons from East Asia. World Bank Technical Paper Number 117. Washington, D.C.The World Bank. :xvi, 111p. 1990.

Batie, S.S. Sustainable Development: Challenges to the Profession of Agricultural Economics. American Journal of Agricultural Economics :1083-1101, 1989.

Bishop, R.C. Endangered Species and Uncertainty: The Economics of a Safe Minimum Standard. American Journal of Agricultural Economics:10-18, 1978.

Borlaug, N.E. The Green Revolution Past Success and Future Challenges. In: 34th Convocation Indian Agricultural Research Institute, edited by Borlaug, N.E.New Delhi:IARI, 1996,p. 1-22.

Bramble, B.J. An Environmentalists's view of Pest Management and the Green Revolution. Tropical Pest Management 35(3):228-230, 1989.

Byerlee, D. and Siddiq, A. Has the Green Revolution Been Sustained? The Quantitative Impact of the Seed-Fertilizer Revolution in Pakistan Revisited. World Development 22(9):1345-1361, 1994.

Carroll, C.R., Vandermeer, J.H., and Rosset, P.M. Agroecology, New York: McGraw-Hill Publishing Company, 1990. pp. xiv + 641

Charoenwatana, T. and Rambo, A.T.(.). Sustainable Rural Development in Asia: Selected Papers from the Fourth SUAN Regional Symposium on Agroecosystem Research, Thailand:Khon Kaen University, 1988.pp. xi + 246

Chambers, R. Microenvironments Unobserved. Environment and Development Gatekeeper Series No. 22. London:IIED. :18p. 1990.

CIMMYT. Toward The 21st Century: CIMMYT's Strategy, Mexico, D.F.CIMMYT, 1989.pp. 78

Conway, G.R. Agroecosystem Analysis for Research and Development, Bangkok:Winrock International Institute, 1986.pp. ix, 111p.

Crosson, P. Sustainable Food and Fiber Production. Presented at the annual meeting of the American Association for the Advance of Science, Chicago, 9 February, 1992.

Drinkwater, M. and McEwan, M.A. Household Food Security and Environmental Sustainability in Farming Systems Research: Developing Sustainable Livelihoods. Journal for Farming Systems Research-Extension 4(2):111-126, 1994.

Edwards, C.A. The Concept of Integrated Systems in Lower Input/ Sustainable Agriculture. American Journal of Alternative Agriculture 2(4):148-152, 1987.

Fujisaka, S., Harrington, L., and Hobbs, P. Rice-Wheat in South Asia: Systems and Long-Term Priorities Established Through Diagnostic Research. Agricultural Systems 46:169-187, 1994.

Gliessman, S.R., Garcia, R., and Amador, M. The Ecological Basis for the Application of Traditional Agricultural Technology in the Management of Tropical Agro-Ecosystems. Agro-Ecosystems 7:173-185, 1981.

Grafton, R.Q., Walters, E.B., and Bertelsen, M.K. An Evaluation of a FSR/E Project: Costs and Benefits of Research and Extension. Agricultural Systems 34:207-221, 1990. Harrington, L. Sustainability, Economics and Ecology: Issues and Opportunities for IARC Social Scientists. 1992. Paper Presented at the Meeting of CGIAR Social Scientists, ISNAR, The Hague, August 17-20, 1992a.

Harrington, L. Interpreting and Measuring Sustainability: Issues and Options. Paper Presented at the NARS/CIMMYT/IRRI Workshop on Measuring Sustainability Through Farmer Monitoring, 6-9 May, 1992, Kathmandu, Nepal.1992b.

Harrington, L., Morris, M., Hobbs, P.R., Pal Singh, V., Sharma, H.C., Singh, R.P., Chaudhary, M.K., and Dhiman, S.D.(.). Wheat and Rice in Karnal and Kurukshetra Districts, Haryana, India Practices, Problems and an Agenda for Action.Anonymous HAU/ICAR/CIMMYT/IRRI. :viii, 75p. 1992.

Harrington, L., Jones, P., and Winograd, M. Operationalizing Sustainability: A Total Productivity Approach. 1994. Paper Presented at the Land Quality Indicators Conference, CIAT: Cali, Jun 1994.

Harrington, L., Morris, M., Hobbs, P.R., Pal Singh, V., Sharma, H.C., Singh, R.P., Chaudhary, M.K., and Dhiman, S.D.(.). Wheat and Rice in Karnal and Kurukshetra Districts, Haryana, India Practices, Problems and an Agenda for Action. HAU/ICAR/CIMMYT/IRRI. :viii, 75p. 1992.

Harwood, R.R. The Contribution of Agroecology to Development of a Sustainable Agriculture. Unpublished draft. 1988.

Hildebrand, P.E. and Ashraf, M. Agricultural Sustainability as an Operational Criterion. 1989. Paper Presented at the Ninth Annual International Farming Systems Symposium, University of Arkansas Fayetteville, October 8-11, 1989.

Holden, S.T. Peasant Household Modelling: Farming Systems Evolution and Sustainability in Northern Zambia. Agricultural Economics 9(3):241-267, 1993. IRRI. Report of a Workshop on Cropping Systems Research in Asia, Philippines:IRRI, 1982.pp. 754

Lele, U. Building on the NARS-CGIAR Partnerships for a Doubly Green Revolution: A Framework for the IFAD-Led Initiative. 1995.

Pieri, C., Dumanski, J., Hamblin, A., and Young, A. Land Quality Indicators. World Bank Discussion Papers No. 315.Anonymous Anonymous Washington, D.C.The World Bank. :viii + 63, 1995. ISSN 0259-210X.

Pingali, P. and Rosegrant, M.W. Conforting the Environmental Consequences of the Green Revolution in Asia. EPTD Discussion Paper No. 2. Washington,D.C.IFPRI. :31p. 1994.

Powell, J.M. and Williams, T.O. Livestock, Nutrient Cycling and Sustainable Agriculture in the West African Sahel. Gatekeeper Series No. SA37. London: IIED. :15p. 1993.

Renkow, M. Technology, Production Environment, and Household Income: Assessing the Regional Impacts of Technological Change. Agricultural Economics 10(3):219-231, 1994.

Roche, F.C. Java's Critical Uplands: Is Sustainable Development Possible? Food Research Institute Studies 21(1):1-37p. 1988.

Schuh, G.E. and Barghouti, S. Meeting the Challenge of Diversification Out of Rice Production in Asia: Towards a Research Agenda. 1987. Paper Presented at Meetings of Consultative Group for International Agricultural Research, Montpellier, France, May 18-22, 1987.

Serageldin, I. and Steer, A. Valuing the Environment: Proceedings of the First Annual International Conference on Environmentally Sustainable Development. ESD Proceedings Series No. 2. Washington, D.C.The World Bank: vi, 192p. 1994.

Sharma, R. and Poleman, T.T. The New Economics of India's Green Revolution: Income and Employment Diffusion in Uttar Pradesh, New Delhi:Vikas Publishing House Pvt Ltd, 1994.pp. xix + 272

Shinawatra, B. Rethinking the Impact Assessment of Farming Systems Research. Journal Asian Farming Systems Association 2(2):246-256, 1994.

Singh Gill, K. Diversification of Agriculture in Punjab: Progress and Possibilities. Agricultural Situation in India 47(5):313-320, 1992.

Smale, M. Ongoing Research at CIMMYT: Understanding Wheat Genetic Diversity and International Flows of Genetic Resources. World Wheat Facts and Trends Supplement, 1995. CIMMYT. Mexico, D.F.CIMMYT:iv + 40, 1995.

Smale, M., Kaunda, Z.H.W., Makina, H.L., Mkandawire, M.M.M.K., Msowoya, M.N.S., Mwale, D.J.E.K., and Heisey, P. Chimanga Cha Makolo, Hybrids, and Composites: An Analysis of Farmers' Adoption of Maize Tchnology in Malawi, 1989-91. CIMMYT Economics Working Paper 91/04. Mexico, D.F.CIMMYT: x + 62, 1991.

Tripp, R.(.). Planned Change in Farming Systems: Progress in On-Farm Research, New York:John Wiley & Sons, 1991.pp. x, 348p.

Tripp, R., Anandajayasekeram, P., Byerlee, D., and Harrington, L. FSR: Achievements, Deficiencies and Challenges for the 1990s. Journal Asian Farming Systems Association 1(2):259-271, 1991.

Vosti, S.A., Witcover, J., and Lipton, M. The Impact of Technical Change in Agriculture on Human Fertility: District-Level Evidence From India. EPTD Discussion Paper No. 5. Washington, D.C.IFPRI. :69p. 1994.

Waddington, S., Edmeades, G.O., Chapman, S.C., and Barreto, H.J. Where to With Agricultural Research for Drought-Prone Maize Environments? 1994. Paper Presented at the Fourth Eastern and Southern Africa Regional Maize Conference, Harare, Zimbabwe, 28 March - 1 April 1994.


Top

© CIMMYT October 1997