Nitrous Oxide Emissions From Bioenergy Feedstocks.

The sustainability of any cellulosic bioenergy feedstock production system is in part a function of its ability to decrease net greenhouse gas emissions into the atmosphere compared to the combustion of fossil fuels.  Nitrous oxide emissions can be a significant component of the total greenhouse gas budget for a bioenergy feedstock production system.  Few studies have evaluated N₂O emissions from forage sorghum grown for cellulosic bioenergy and no research has been conducted to evaluate this important component of the production system in Oklahoma.  The objective of this study was to evaluate the response in N₂O emissions to a range of N rates applied to forage sorghum, switchgrass and mixed grasses.  This study was initiated at Stillwater, Oklahoma in spring 2010, when forage sorghum (ES 5200, Ceres Inc), switchgrass and mixed native grasses were planted.  Nitrous oxide emissions were measured using a vented chamber technique. These measurements were collected weekly until side-dress fertilizer application.  Emissions were then measured daily after fertilization for 5 days and then every other day for an additional 5 days at which time sample frequency became weekly for the duration of the growing season.  This data will be useful in developing a greenhouse gas lifecycle analysis for forage sorghum, switchgrass and mixed grasses in the Central Great Plains.