The State Key Laboratory of Grassland Agro-Ecosystems, Lanzhou University, Lanzhou 730020, China.
College of Pastoral Agri-Culture Science and Technology, Lanzhou University, Lanzhou 730020, China.
Int J Environ Res Public Health. 2022 Jun 24;19(13):7789. doi: 10.3390/ijerph19137789.
Nitrous oxide (NO) is a potent greenhouse gas. Assessing the NO emission from lucerne grasslands with nitrogen addition will aid in estimating the annual NO emissions of such agriculture areas, particularly following summer rainfall events in light of precipitation variation associated with global change. Here, we measured soil NO emissions, soil temperature and water content of lucerne grasslands with four levels of nitrogen addition over 25 days, which included 10 rainfall events. Results showed that nitrogen addition was observed to increase soil NO-N content, but not significantly improve dry matter yield, height or leaf area index. Nitrogen addition and rainfall significantly affected NO emissions, while the response of NO emissions to increasing nitrogen input was not linear. Relative soil gas diffusivity (D/D) and water-filled pore space (WFPS) were good indicators of NO diurnal dynamics, and D/D was able to explain slightly more of the variation in NO emissions than WFPS. Collectively, nitrogen addition did not affect lucerne dry matter yield in a short term, while it induced soil NO emissions when rainfall events alter soil water content, and D/D could be a better proxy for predicting NO emissions in rainfed lucerne grasslands.
一氧化二氮（NO）是一种强效温室气体。评估添加氮后卢瑟恩草原的一氧化二氮排放，将有助于估算此类农业区的年一氧化二氮排放量，特别是在考虑到与全球变化相关的降水变化的情况下，夏季雨后事件。在这里，我们在 25 天内测量了添加氮的 4 个水平的卢瑟恩草原的土壤一氧化二氮排放、土壤温度和含水量，其中包括 10 次降雨事件。结果表明，氮添加被观察到增加土壤 NO-N 含量，但对干物质产量、高度或叶面积指数没有显著提高。氮添加和降雨显著影响了一氧化二氮的排放，而一氧化二氮排放对增加氮输入的响应不是线性的。相对土壤气体扩散率（D/D）和水填充孔隙空间（WFPS）是一氧化二氮日动态的良好指标，D/D 能够比 WFPS 更好地解释一氧化二氮排放的变化。总的来说，氮添加在短期内不会影响卢瑟恩的干物质产量，而当降雨事件改变土壤水分含量时，氮添加会诱导土壤一氧化二氮排放，D/D 可以作为预测雨养卢瑟恩草原一氧化二氮排放的更好替代指标。
