The Special Report on Land use, Land-use Change, and Forestry (IPCC, 2000a) estimated a significant potential for increasing carbon stocks in the agricultural sector. Improved management of cropland and grazing-lands, agroforestry, and rice paddies have the potential to sequester 398 MtC annually, and the conversion of cropland to agroforestry practices and grasslands can sequester an additional 428 MtC annually by 2010. These estimates are highly uncertain, however, and do not include the impact on the net emissions of methane (CH₄) or nitrous oxide (N₂O) from agricultural practices or wetlands and/or permafrost management.

CH₄ emissions from agriculture produce about eight per cent of the radiative forcing of all GHGs (Watson et al., 1996). CH₄ from manure can be captured and used for fuel; emissions from ruminants can be reduced with better diets, feed additives, and breeding; and emissions from rice paddies can be mitigated by nutrient management, water management, altered tillage practices, cultivar selection, and other practices (Mosier et al., 1998).

Many of the mitigation options to address these opportunities may provide multiple benefits to the farmer and society at large. Improving soil management for crop production, for instance, can also improve water relations, nutrient retention, and nutrient cycling capacity (Paustian et al., 1998). Retiring surplus agricultural lands can result in improved water quality, reduced soil erosion, and increased wildlife habitat. As Izac (1997) points out, however, farmers, who will be the ultimate decision makers about which mitigation option to adopt, have shorter planning horizons than national or international beneficiaries, and many mitigation options ask them to bear costs up front while the benefits are longer term and to the society at large.

Furthermore, in order to realize these opportunities a very large proportion of farmers who pursue diverse agricultural practices will have to be convinced to adopt mitigation options. Economic, cultural, and institutional barriers exist which restrict the rate of adoption of such practices. Farmers who are accustomed to traditional practices may be reluctant to adopt new production systems. Crop price supports, scarcity of investment capital, and lack of economic incentives for addressing environmental externalities are some of the economic barriers. Limited applicability of mitigation options to different types of agriculture, negative effects on yield and soil fertility for rice production, and the increased skilled labour requirements are some of the other constraints. Among these barriers the especially critical ones are highlighted here.

Farm-level Adoption Constraints
Several generic constraints characterize the adoption of most new agricultural technology. These include small farm size, credit constraints, risk aversion, lack of access to information and human capital, inadequate rural infrastructure and tenurial arrangements, and unreliable supply of complementary inputs. Participatory arrangements that fully engage all the involved actors may help to overcome many of these barriers.

Government Subsidies
Subsidies for critical inputs to agriculture, such as fertilizers, water supply, and electricity and fuels, and to outputs in order to maintain stable agricultural systems and an equitable distribution of wealth can distort markets for these products. These types of subsidies prevail in both developed and developing countries. Low electricity prices in India, for example, provide a disincentive for the use of efficient pump sets, and encourage increased use of ground water, which depletes the water reservoirs. In the OECD, for example, high levels of farm subsidies have also contributed to the intensification of farm practices and often provide incentives to increase fertilizer use, livestock density, etc. (Storey, 1997).

Lack of National Human and Institutional Capacity and Information in the Developing Countries
Several of the Consultative Group on International Agricultural Research (CGIAR) systems are experiencing difficulty as their funding slows. The systems have not transferred capacity to national centres in the developing countries that they are expected to serve. The national centres also lack access to information, and are not aware of technologies that suit their local conditions (IPCC, 2000b).

Intellectual Property Rights
To some extent the reduced public funding on new technologies has been replaced by the private sector’s contribution. Private sector funding offers one approach to increasing investment for mitigation projects worldwide. Private plant breeding research has more than quadrupled in the USA in real terms between 1970 and 1990. Its international role is, however, controversial. Protection of intellectual property rights is weak, especially for commercially developed seed varieties (Deardorff, 1993; Frisvold and Condon, 1995, 1998; Knudson, 1998). On the other hand, hybridization will help to stimulate more investment from the private sector at the risk of increasing the farmers’ dependency on the annual purchase of new seeds. There are also concerns that genetic resources that have not been considered as privately-owned intellectual property may get patented worldwide by private investors.

Several measures may be pursued to address the above barriers. These include

• The expansion of internationally supported credit and savings schemes, and price support, to assist rural people to manage the increased variability in their environment (Izac, 1997);
• Shifts in the allocation of international agricultural research for the semi-arid tropics towards water-use efficiency, irrigation design, irrigation management, and salinity, and the effect of increased CO₂ levels on tropical crops (Tiessen et al., 1998);
• The improvement of food security and disaster early warning systems, through satellite imaging and analysis, national and regional buffer stocks, improved international responses to disasters, and linking disaster food-for-work schemes to adaptation projects (e.g., flood barricades);
• The development of institutional linkage between countries with high standards in certain technologies, for example flood control; and
• The rationalization of input and output prices of agricultural commodities taking DES issues into consideration which would lead to more efficient use of input resources.
  

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