S. K. Guru
1.11 Barriers and opportunities/implementation issues
The contribution of agriculture to global GHG emissions ranges from 5.1 to 6.1 Gt CO2-eq. The global potential of ara- ble and permanent cropping systems to sequester is 200 kg C ha−1 year−1 and pasture systems is 100 kg ha−1 year−1; the world’s carbon sequestration will amount to 2.4 Gt CO2-eq. year−1 (Lal, 2004a; Niggli et al., 2009). This minimum scenario for a con- version to organic farming would mitigate 40% of the world’s agriculture GHG emissions (Niggli et al., 2009). The sequestra- tion rate on arable land adopting organic farming with reduced tillage techniques will be 500 kg C ha−1 year−1, which will contribute 65% mitigation of the agricultural GHG and, thus, total global organic mitigation would be 4 Gt CO2-eq. year−1. This indicates that application of sustainable management tech- niques to build up soil organic matter have the potential to bal- ance a large part of the agricultural emissions although their effect over time may be reduced as soils are built up (Foereid and Høgh-Jensen, 2004). By a conversion to organic farming, another approximately 20% of the agricultural GHG could be reduced by abandoning industrially produced nitrogen fertilis- ers as is practiced by organic farms. This encouraging figure strongly supports the reality of low GHG agriculture and the possibility of climate neutral farming.
1.10 Agricultural GhG mitigation
financial resources and technical assistance, as well as the avail- ability of other inputs, such as water and fertiliser. Uncertainty about the timing and rate of climate change also limits adaptation and, if expectations are incorrect, could contribute to the costs associated with transition and disequilibrium. The barriers to adoption of carbon sequestration activities on agricultural lands following Smith et al. (2007a) are discussed below.
Carbon sequestration in soils or terrestrial biomass is a rapid and cheap available option that needs 15–60 years to reach a maximum capacity for the ecosystem, depending on manage- ment practice, management history and the system (West and Post, 2002; Caldeira et al., 2004; Sands and McCarl, 2005).
Mostly, agricultural mitigation options are reversible and a change in management can reverse the gains in carbon seques- tration. Reduction in N2O and CH4 emissions, avoiding emis- sions as a result of agricultural energy efficiency gains and the substitution of fossil fuels by bioenergy are non-reversible (Smith et al., 2007a).
The GHG net emission reduction is assessed relative to a base- line, but selecting an appropriate baseline is a problem (Smith et al., 2007a).
Complex biological and ecological processes involved in GHG emissions and carbon storage is complex and less understood (mechanism uncertainty). This makes investors shy away from the agricultural mitigation options. Moreover, agricultural sys- tems exhibit substantial variability between seasons and loca- tions, creating high variability in offset quantities at the farm level (measurement uncertainty), which can be reduced by increasing the geographical extent and duration of the account- ing unit (Kim and McCarl, 2005).
Adopting certain agricultural mitigation practices may reduce production within implementing regions. However, this ben- efit may be offset by increased production outside the project region unconstrained by GHG mitigation objectives reducing the net emission. ‘Wall-to-wall’ accounting can detect this and crediting correction factors may need to be employed (Murray et al., 2004; Anonymous, 2005b).
Under an incentive-based system such as a carbon market, the amount of money farmers receive is not the market price but Maxi mum
storage
Revers ibility
Baseline
Uncer tainty
Displace ment of emissions
trans action costs
the market price, less brokerage cost. This may be substantial and is an increasing fraction as the amount of carbon involved diminishes, creating a serious entry barrier for smallholders.
In developing countries, this could involve many thousands of farmers (Smith et al., 2007a).
Such costs can be either minimal (Mooney et al., 2004) or large (Smith, 2004c). In general, measurement costs per carbon- credit sold decrease as the quantity of carbon sequestered and area sampled increase. Methodological advances in measur- ing soil carbon may reduce costs and increase the sensitivity of change detection. However, improved methods to account for changes in soil bulk density remain a hindrance to quanti- fication of changes in soil carbon stocks (Izaurralde and Rice, 2006). With the development of remote sensing, new spectral techniques to measure soil carbon and modelling offer oppor- tunities to reduce costs, but will require evaluation (Ogle and Paustian, 2005; Brown et al., 2006; Izaurralde and Rice, 2006;
Gehl and Rice, 2007).
Property rights, landholdings and the lack of a clear single- party land ownership in certain areas may inhibit implementa- tion of management changes (Smith et al., 2007a).
The other possible barriers to implementation include the avail- ability of capital, the rate of capital stock turnover, the rate of technological development, risk attitudes, need for research and outreach, consistency with traditional practices, pressure for competing uses of agricultural land and water, demand for agricultural products, high costs for certain enabling technolo- gies and ease of compliance (e.g. straw burning is quicker than residue removal and can also control some weeds and diseases, so farmers favour straw burning) (Smith et al., 2007a).
Considering the growing concern of elevated atmospheric GHGs, the complex economics and availability of fossil fuels and the deterioration of the environment and health conditions with a shift away from intense reliance on heavy chemical inputs to an intense biologically-based agriculture and food system is possible today (Niggli et al., 2009). Sustainable and organic agriculture offers multiple opportunities to reduce GHGs and counteract global warming. Organic agriculture reduces energy requirements for production systems by 25–50% compared to conventional chemical-based agriculture. Reducing GHGs through their sequestration in soil has even greater potential to mitigate climate change. Soil improvement is essential for Measure ment
and monitoring costs
property rights
Other barriers
agriculture in developing countries where crop inputs (chemical fertilisers and pesticides) are costly and unavailable. Further, this requires special equipment and knowhow for their proper application which is not widespread.
Productive and ecologically sustainable agriculture is cru- cial to reduce trade-offs among food security, climate change and ecosystem degradation. Organic agriculture therefore rep- resents a multi-targeted and multi-functional strategy. It offers a proven alternative concept that is being implemented quite successfully by a growing number of farms and food chains.
Currently, 1.2 million farmers practice organic agriculture on 32.2 million ha of land (Willer and Kilcher, 2009). Many com- ponents of organic agriculture can be implemented within other sustainable farming systems. The system-oriented and partici- pative concept of organic agriculture combined with new sus- tainable technologies (such as no tillage) offer greatly needed solutions in the face of climate change (Niggli et al., 2009).