Tradeoffs occur between different development goals when different choices of AKST investments on specific commodities or types of institutions are made (Table 8-20). For example, RORs to wheat research have been high (see 8.2.4), but the research that produced high-yielding wheat varieties may also have induced more irrigation of wheat in poorly drained regions, which has led to increased sa­linity, destroyed land, and displaced farmers. Pesticide use on wheat is limited so there has been little negative impact of pesticides.   Green revolution wheat varieties reduced prices of wheat, which increased consumption of wheat by the poor improving their health. The high yielding wheat varieties during the green revolution period in South Asia increased demand for labor and thus the incomes of the poor (Lipton, 2001). An example of research that has posi­tive effects on economically sustainable development, but a negative impact on other development goals is research to increase the productivity of intensive livestock produc­tion. It has high RORs but major negative environmental effects through water and air pollution, and negative health impacts through E. coli and other public health crises (see 8.2.5 and 8.2.6). At the same time it can have positive health impacts through dramatic declines in the price of meat and poultry, which in turn facilitates access for more people to animal protein and other essential nutrients.

8.4.2.1 Options for societies aiming to give major support to environmental sustainability
For these societies investment in AKST can have three dif­ferent, but complementary, alternatives: reducing the nega­tive environmental impacts of farming systems, enhancing existing agricultural systems that have been shown to be environmentally sustainable, and developing new agricul­tural systems. They will have to focus on providing eco­system services such as reduced greenhouse gas emissions, absorption of the carbon dioxide, reduced water pollution and slowing the loss of biodiversity.
         We have made judgments about the most important negative impacts of agricultural technologies on the envi­ronment (see 8.2.5); unfortunately, data is not available to know which of the impacts are most important or which negative impacts could be mitigated most effectively through investments in AKST. This gap suggests that the first impor­tant need for AKST investment is for social and ecological scientists working with other scientists to develop method­ologies and to quantify the externalities of high and low external input farming systems from a monetary perspec­tive as well as from other perspectives such as the concept of energy flows used in "emergy" evaluations. Evidence on these externalities' potential implications on food security also needs to be analysed.
        There are three other types of AKST investments in which countries can invest. First is research to develop man­agement practices, technologies, and policies that reduce the ecological footprint of agriculture, such as reducing agricul­ture's use of fossil fuels, pesticides and fertilizers. This would include AKST investments to develop management practices such as: no-tillage systems to reduce use of fossil fuels for till­age, integrated pest management strategies to avoid overuse of inorganic pesticides, integrated soil management technol­ogies to reduce the need for inorganic fertilizer, rotational

grazing and support of mixed farming systems to improve the nutrient cycling within agriculture and livestock produc­tion. In this area, investments on sustainable and low-input farming practices would also be recommended. AKST in­vestments can also increase agriculture's role as a carbon sink. The greatest dividends would come from conversion from grain crops to agroforestry as there is a benefit from both increased soil organic matter and the accumulation of above-ground woody biomass. Thus agroforestry can play a major role in the two key dimensions of climate change: mitigation of greenhouse gas emissions and adaptation to changing environmental conditions (Garrity, 2004). Other management strategies such as including grasslands within rotations, zero-tillage (or no-till) farming, green manures, and high amendments of straw and manures, would also lead to substantial carbon sequestration (Pretty and Ball, 2001).         A second type of AKST activity would be the develop­ment of biological substitutes for industrial chemicals or fossil fuels. These would include new biopesticides, im­provements in biological nitrogen fixation, and search for alternative sources of energy that do not compete with food production and do not induce deforestation. There is some evidence that research in this area can provide a good eco­nomic ROR, and the RORs are likely to rise as more gov­ernments put policies in place that reward farmers for the provision of these services.
         Third, research to support traditional knowledge on effective ways of using and conserving available resources such as soils, water, and biodiversity to improve rural liveli­hoods will be required. This knowledge has been neglected but research and management systems based on this knowl­edge have been shown to have positive ecological and eco­nomical impacts in all areas of agriculture (crops, livestock, aquaculture and agroforestry). New nonconventional crops and breeds may play a vital role in the future for conserving local and indigenous knowledge systems and culture, as they have a high local knowledge base which is being promoted through participatory domestication processes (Leakey et al., 2005; World Agroforestry Centre, 2005; Garrity, 2006; Tchoundjeu et al., 2006).
          This may be an area of AKST that had lower returns to public investments research than some other types of re­search historically. This is due in part to the difficulty of measuring the impact of research in this area and the lack of studies of the impact of these types of research. It is also partly due to the fact that the complementary policies and institutions needed to implement solutions developed by AKST are often not in place. Considering that agriculture and land use contribute to 32% of global emissions, more research is needed to analyse the potential contribution of new and existing but ignored agricultural technologies and practices that could contribute to decreasing global warm­ing and climate change. Another important type of research investment needed is social science research which develops recommendations for policy and institutional changes that reward farmers for reducing the negative externalities, en­hancing the multiple functions of agriculture, and for the provision of ecosystem services. Investments in incentives for private sector to develop technologies that assist farmers to provide ecosystems services are also needed.