3. CH₄ Emissions from Rice Cultivation

Anaerobic decomposition of organic material in flooded rice fields produces CH₄, which escapes to the atmosphere primarily by diffusive transport through the rice plants during the growing season.  However, during land preparation and initial growth of rice, ebullition (bubbles) is the major release mechanism.  Diffusion loss of CH₄ across the water surface is the least significant process (in terms of the volume of emissions).  Upland rice fields, which are not flooded, do not produce significant quantities of CH₄.

• The amount of CH₄ emitted varies from one site to another due to various conditions, such as climatic conditions, number and duration of crops grown, soil type and texture, ecosystem type and water management practices (flooding pattern), and the use of fertilizers (sulphate containing amendments) and other organic and inorganic amendments.  These affect important factors that determine emissions such as the redox potential of the soil, soil temperature, and the carbon substrate and nutrient availability.