Direct and Indirect Nitrous Oxide Emissions: Contrasting Effects of Nitrogen Management Practices in Their Mitigation Efforts.

Nitrous oxide (N2O) is a major greenhouse gas and also the single most important ozone-depleting emission. Soil-to-atmosphere direct emission of N2O from agricultural land is measured right on field using static chamber method or covariance flux tower. Other forms of environmental nitrogen (N) losses such as nitrate leaching, ammonia volatilization, or nitric oxide emission from agricultural fields can also contribute to indirect N2O emission in downstream ecosystems, which in some cases can be significant. These indirect N2O emissions are difficult to measure. IPCC has published emission factors based on a limited published work to account for indirect N2O due to N losses other than direct N2O emission. This paper compiles published work that report on direct N2O emission along with other forms of N losses. Majority of those published work suggest contrasting effects of N management practices in mitigation of direct versus indirect N2O emissions. This paper highlights a greater complexity of already challenging nature of the problem at hand.