Nitrous oxide emissions from different land uses affected by managements on the Qinghai-Tibetan Plateau

•Cultivating alpine grassland significantly stimulates N2O emissions.•Sheep manure causes lower N2O emission than N fertilizer in alpine grassland.•No-tillage can mitigate increased N2O emissions caused by grassland cultivation.

We evaluated the N2O emissions from four land use types (a native alpine meadow with winter grazing (NAM), an abandoned pasture (APL), a perennial Elymus nutans Griseb. pasture (PEN) and an annual Avena sativa L. pasture (AAS)) with and without three management practices (nitrogen (N) fertilizer, sheep manure and no tillage (NT)) in a Gelic Cambisol soil underlying an alpine meadow on the Qinghai-Tibetan Plateau in 2009 and 2010. Our results show that, compared with NAM, APL had significantly higher cumulative-average seasonal N2O emissions. Converting unmanaged APL to PEN or AAS significantly increased cumulative-average seasonal N2O emissions by 35% and 75%, respectively. Sheep manure and N fertilizer application significantly increased N2O emissions due to increased soil inorganic N concentration. The effect of sheep manure addition on N2O emissions was lower than that of N fertilizer. For AAS, tillage significantly decreased the effect of sheep manure application on N2O emissions. Compared with tillage, NT significantly decreased N2O emissions from AAS. Therefore, our results suggest that cultivating natural grassland would increase N2O emissions, and fertilizer application would amplify the magnitude of emissions, whereas NT could mitigate the fertilizer impact on N2O emission. Furthermore, the structural equation analysis revealed that land use change affected N2O emissions directly by influencing the number of plant species and soil characteristics. There were two different underlying mechanisms regulating N2O emissions in response to N fertilizer and sheep manure addition.