TVace gas exchange in rice cultivation

Rice cultivation constitutes a source of numerous atmospheric trace gases including CH4, N20, and reduced sulfur compounds. Sufficient information to estimate the source strength of rice cultivation on a global scale is only available for CH4. Though these estimates still have a high degree of uncertainty, rice cultivation has been identified as one of the most important individual sources of atmospheric CH4. Trace gas emission in rice cultivation is the net result of interconnected microbial processes and plant-microbial interactions. This review summarizes the present knowledge on production, consumption, and transport of atmospheric trace gases in rice paddies. The available field data on the diurnal and seasonal variations, regional differences, and the effect of agricultural practices are discussed on the basis of the biological and physico-chemical processes involved.