Research Highlights: Intensive nitrogen (N) application for agricultural purposes has substantially increased soil nitrous oxide (N₂O) emissions. Agricultural soil has great potential in the reduction of N₂O emissions, and applications of biochar and nitrification inhibitors may be useful for mitigating agricultural soil N₂O emissions. Background and Objectives: Camellia oleifera Abel. is an important woody oil plant in China. However, intensive N input in C. oleifera silviculture has increased the risk of soil N₂O emissions. As an important greenhouse gas, N₂O is characterized by a global warming potential at a 100-year scale that is 265 times that of carbon dioxide. Thus, mitigation of soil N₂O emissions, especially fertilized soils, will be crucial for reducing climate change. Materials and Methods: Here, we conducted an in situ study over 12 months to examine the effects of C. oleifera fruit shell-derived biochar and dicyandiamide (DCD) on soil N₂O emissions from a C. oleifera field with intensive N application. Results: A three-fold increase of cumulative soil N₂O emissions was observed following N application. Cumulative N₂O emissions from the field with N fertilization were reduced by 36% and 44% with biochar and DCD, respectively. While N₂O emissions were slightly deceased by biochar, the decrease was comparable to that by DCD. Conclusions: Results indicated that biochar may mitigate soil N₂O emissions substantially and similarly to DCD under specific conditions. This result should be examined by prolonged and multi-site studies before it can be generalized to broader scales.

Under the macroenvironmental background of global warming, all countries are working to limit climate change. Internationally, biofuel plants are considered to have great potential in carbon neutralization. Several countries have begun using biofuel crops as energy sources to neutralize carbon emissions. Switchgrass (Panicum virgatum) is considered a resource-efficient low-input crop that produces bioenergy. In this paper, we reviewed the effects of switchgrass cultivation on carbon sequestration and greenhouse gas (GHG) emissions. Moreover, the future application and research of switchgrass are discussed and prospected. Switchgrass has huge aboveground and underground biomass, manifesting its huge carbon sequestration potential. The net change of soil surface 30 cm soil organic carbon in 15 years is predicted to be 6.49 Mg ha⁻¹, significantly higher than that of other crops. In addition, its net ecosystem CO₂ exchange is about −485 to −118 g C m⁻² yr⁻¹, which greatly affects the annual CO₂ flux of the cultivation environment. Nitrogen (N) fertilizer is the main source of N₂O emission in the switchgrass field. Nitrogen addition increases the yield of switchgrass and also increases the N₂O flux of switchgrass soil. It is necessary to formulate the most appropriate N fertilizer application strategy. CH₄ emissions are also an important indicator of carbon debt. The effects of switchgrass cultivation on CH₄ emissions may be significant but are often ignored. Future studies on GHG emissions by switchgrass should also focus on CH₄. In conclusion, as a biofuel crop, switchgrass can well balance the effects of climate change. It is necessary to conduct studies of switchgrass globally with the long-term dimension of climate change effects.