Page 38 - FAO-IPCC Expert meeting on climate change

Greenhouse gas fluxes from agriculture and land systems: a scoping of mitigation options
highly but relate only to small land areas. Other practices are able to cover broad strips of land, although the gain in carbon sequestration is relatively small.32
To develop reliable metrics that allow for the quantification and verification of emission reductions and SCS is a major challenge. The difficulty in terms of land use is that the sources and sinks of soil produce a non-point source emission, and are spatially and temporally variable. Moreover, it is essential that these metrics be applied by decision-makers, including not only scientists, but also farmers and land managers. While the current knowledge base is extensive, particularly in developed countries, gathering information and establishing monitoring networks are essential to identify and measure soil carbon alterations. The technical capacity by way of remote sensing and soil mapping is
much broader; however, the sources of relevant data should be centralized, together with improved scientific and technological models. Engagement with land users is critical to develop support systems that enable policy intervention, create carbon offset markets and manage supply chains.
3.4 Mitigation options in agriculture and land-based ecosystems
3.4.1 Rice production33
Rice is a crop that is flooded for much of the season, creating anaerobic conditions that lead to substantial methane emissions. GHG emissions can be reduced by: changing the water regime; reducing flooding periods; and a shorter season rice (i.e. 90−100 days compared with 140−160 days) that reduces the time flooring, resulting in fewer GHG emissions. Rice research at IRRI focuses on improved irrigation techniques that will reduce emissions, such as alternate wetting and drying. IRRI researchers are analysing ways in which to scale up alternate wetting and drying techniques and convince farmers of their benefits. While the technology is simple, its adoption has not been straightforward. The major challenge lies in the policy and institutional environment as well as market conditions, rather than in the technology. The absence of economic incentives for farmers to adopt a labour-intensive activity that requires pumping water, when water is available for free in many places, makes it difficult. Were there a cost for the water used in production, farmers would then have a reason to save it by embracing the technique of alternate wetting and drying. For now, the benefit of mitigation alone does not justify the practice enough for farmers to adopt it.
Another technology with potential mitigation advantages is the use of site-specific nutrient management to reduce the application of fertilizer in rice. IRRI has developed a mobile phone application, the Rice Crop Manager Advisory Service, which provides farmers with a personalized crop and nutrient management guidelines, including the type of nutrients to use, field preparation, crop establishment and pest management. The app has a module that estimates GHG emissions and offers a climate forecaster and certain warning systems on salinity in coastal zones.
Post-harvest techniques include mechanized alternatives to incorporating burnt straw into the soil to reduce methane and nitrous oxide emissions. Straw can act as fire fuel in cooking stoves, forming a biochar by-product that can be used to fertilize the soil and reduce methane gas the following season. Cooking stove technology, however, is under development and the uptake has not yet been wide.
IRRI is also exploring the gelatinization temperature of rice – this determines the cooking time for any particular variety. Rice varieties that take less time and energy emit fewer GHG. Creating such opportunities for abatement on the consumer side will expand the options for mitigation along the food supply chain.
3.4.2 Livestock and rangeland
Emissions from livestock are of two types: enteric methane (40 percent of total livestock emissions on average) and manure management (nitrous oxide and methane). Both sources are natural processes that are difficult to control and are expected to increase as a result of population growth and diets changing in favour of animal protein. In many developing countries, food security, poverty alleviation, climate change adaptation and general improvements in
32 It is estimated that between 4 petagrams and 8 petagrams of CO2 equivalent per annum over approximately a 20−25 year period would be feasible as a total technical potential (i.e. equivalent to 20 percent of current global emissions in terms of carbon dioxide). The case for achieving this was published by P. Smith and colleagues in the 2007 Fourth Assessment Report.
33 Mitigation options from agricultural soils linked to crops other than rice are equally important but were not discussed in detail at the EM because of the limited time assigned to mitigation. However, the supplemental citation list in the Appendix includes a section on NO2 emissions from fertilizer use in other crops.
FAO-IPCC Expert meeting on climate change, land use and food security