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In the long term, mitigating climate change will be critical to avoiding future breakdowns in food and livelihood systems and sharp increases in the number of food-insecure people worldwide. Food systems also have enormous potential to mitigate climate change, however, particularly at the production end of the food chain. Moreover, many of the most effective mitigation measures also represent highly effective adaptation strategies, especially for commercial agriculture.
Good options exist for reducing the current level of agriculture-related emissions and, in the process, introducing more sustainable farming practices that strengthen ecosystem resilience and provide more security for agriculture-based livelihoods in the face of increased climatic variability. These are several the cases study in term of reducing agricultural emissions of Green House Gas
Reducing methane emissions from ruminant livestock
Methane emissions per animal and per unit of livestock product are high when the animals’ diet is poor (EPA Online). Range-fed beef cows are the most important source of methane from enteric fermentation because they are very large animals, even compared with dairy cows; their diets, consisting mainly of forages of varying quality, are generally poorer than those in the dairy or feedlot sectors; the level of management is usually not as good; and the beef cow population is very large. Better grazing management and dietary supplementation have been identified as the most effective ways of reducing emissions from this sector because they improve animal nutrition and reproductive efficiency.
Reducing methane emissions from rice
At between 50 and 100 million tons of methane a year, rice agriculture is a large source of atmospheric methane, possibly the greatest of the human-incurred methane sources. (GHG Online b) As the world population increases, reducing rice agriculture remains largely untenable as a strategy for reducing methane emissions from paddy rice fields. Many rice varieties can be grown under much drier conditions than those traditionally employed, with large reductions in methane emission without any loss in yield. Applying the principles of conservation agriculture to crops such as irrigated rice would provide chances for reducing the water consumption of this cropping system and, by changing the soil environment from mostly anaerobic to aerobic, could also make it easier to fine-tune the irrigation pattern to reduce the emission of methane. There is also great potential for improved varieties of rice that can produce much larger crops per area of rice paddy, thereby allowing for reduced areas of rice paddies without reducing production. The addition of compounds that favour the activity of other microbial groups over that of the methanogens, such as ammonium sulphate, has proved successful under some conditions.
Reducing methane emissions from manure
Although manure is the residue from animals’ digestive processes – so is a waste product – it contains important amounts of nitrogen, phosphates and potassium that provide valuable soil nutrients when applied to farmers’ fields. Poor manure management can increase the loss of pollutants to the environment, however. Nitrogen in manures can be lost as nitrate, nitrous oxide (a greenhouse gas) or ammonia (a constituent of acid rain and a cause of terrestrial eutrophication). There are options for managing manure in ways that do not contribute to greenhouse gas accumulation such as composting and drying, slurry tanks or covered lagoons for trapping the methane released by livestock manure, and other structures for liquid storage.
- PROTECTING FOOD SECURITY THROUGH MITIGATION OF CLIMATE CHANGE (http://www.fao.org/forestry/15538-079b31d45081fe9c3dbc6ff34de4807e4.pdf)