At the Kyoto Conference held in 1997, many nations of the world agreed to reduce greenhouse gas emissions. Most developed countries committed themselves to reduce emissions to an average of five per cent below 1990 levels by the period 2008 to 2012.

Greenhouse gases (GHGs) are atmospheric compounds that store energy, thus influencing the climate. Each of the GHGs has a different global warming potential that takes into account the effectiveness of each gas in trapping heat radiation and its longevity in the atmosphere. For instance, one kilogram of methane (CH₄) is estimated to have the same warming potential as 21 kilograms of carbon dioxide (CO₂), and one kilogram of nitrous oxide (N₂O) has an equivalent impact to approximately 310 kilograms of CO₂.

According to the Organization for Economic Cooperation and Development (OECD), CO₂, CH₄ and N₂O emissions in agriculture at global level are estimated to account for 14 per cent of the total emission of GHGs. However, estimates of both absorption and emission of these three gases are subject to significant uncertainties.

Fertilizers and Gas Emissions

The use of phosphate and potash fertilizers does not contribute directly to GHG emissions, but all forms of nitrogen fertilizers may lead to N₂O emissions.

Since there is no significant uptake mechanism for N₂O in agricultural systems, mitigation focuses on emission reduction. In general, agricultural practices that increase nutrient use efficiency and diminish nitrogen leaching are also appropriate for minimizing N₂O emissions. Best management practices, which match the nitrogen supply to crop requirements and integrate animal manure and crop residue management into crop production, result in a net reduction in N₂O emissions. The proper balance of nutrients optimizes the efficiency of applied and residual soil nitrogen. Other agricultural practices that minimize nitrogen losses include the adoption of reduced tillage practices, the prevention of water-logging through improved drainage and the treatment of sodic soils.

IFA has issued and distributes product-specific codes of best agricultural practice to maximize product efficiency and plant nutrient uptake, while minimizing possible adverse effects to the environment. One example is the code on urea, prepared jointly with the European Fertilizer Manufacturers Association (EFMA).

Whether in organic or inorganic form, excess nitrogen can eventually lead to enhanced N₂O emissions. Globally, nitrogen fixation by leguminous crops adds as much nitrogen to the soil as does commercial fertilizer; thus, they contribute as much to nitrogen emissions as do fertilizers. Organic sources release available nitrogen at a slow rate determined by temperature and moisture, and may continue to release nitrates (NO₃^-) after crop uptake of nitrogen has ceased. This excess NO₃^- is a potential source of additional N₂O emissions.

Biofuels

Agriculture can be a source of clean energy since it has the potential to counterbalance CO₂ emissions from energy use by other sectors, such as transportation. The use of crops for biofuels such as ethanol reduces net GHG emissions, since the carbon (C) in biofuels originates from the CO₂ in the air. In comparison to conventional fuels, fuels containing ten per cent ethanol can reduce net GHG emissions by up to two per cent, while those containing 85 per cent ethanol may reduce emissions by as much as 27 per cent.

Carbon Sequestration

In the UN Framework Convention on Climate Change, the signatory countries of the Kyoto Protocol agreed to include carbon sequestration (agricultural sinks) as an option for mitigating GHGs. Agriculture both absorbs and emits large amounts of carbon dioxide (CO₂). Fertilizer applications increase the amount of dry matter produced by a crop and, thus, increase the net carbon fixed in soils as organic matter when crop residues are returned to the soil. Nitrogen helps to stabilize carbon in soil organic matter: a kilogram of nitrogen is required for every 10 to 12 kilograms of carbon sequestered. The building-up of soil organic matter stocks, and the subsequent increase in soil carbon, can be enhanced using advanced farming practices such as conservation tillage (reduced tillage or no-till), cover crops and improved crop rotations.

IFA's Position

IFA encourages the development of new fertilizers, improvement of fertilizer formulations and a more efficient use of nitrogen fertilizers, through further research, extension activities and training programs aimed at limiting emissions of nitrous oxide and nitrogen oxides.

The fertilizer industry is involved in researching feasible carbon sequestration practices, and IFA urges farmers to adopt best management practices to maximize agriculture's contribution to carbon sequestration.

IFA is committed to work with other stakeholders to achieve these goals.

December 2002