Effects Of Simulated Nitrogen Deposition And Biochar Addition On Dissolved Organic Carbon And Nitrogen In Moso Bamboo Platation

Dissolved organic matter?DOM?is one of the most reactive and mobile components in terrestrial ecosystems,and plays a significant role in carbon and nitrogen?N?cycling of terrestrial ecosystem.Frequent loss of DOM leads to negative effects on the surrounding environment.N deposition may affect DOM leaching,but it remains unclear whether biochar amendment can affect the loss of soil dissolved organic carbon?DOC?or dissolved organic nitrogen?DON?induced by N deposition in Moso bamboo plantation.In this study,we observed the effects of biochar amendments?BC0: 0 t biochar ha-1,BC20: 20 t biochar ha-1,and BC40: 40 t biochar ha-1?on the leaching of soil DOC and DON in Moso bamboo plantations that have received simulated N deposition(N30: 30 kg N ha^-1·yr^–1,N60: 60 kg N ha^-1·yr^–1,N90: 90 kg N ha^-1·yr^–1,and N-free)with two management practices?conventional management?CM?and intensive management?IM??.The study results showed:?1?The concentrations and loss rates of DOC and DON showed marked seasonal variation: DOC and DON concentrations were the highest in summer and the lowest in winter.The loss rate of DOC was the lowest in spring and the highest in summer.?2?N deposition decreased the DOC and DON concentrations in spring and summer?P < 0.05?,but not in winter.On the whole,N deposition increased the leaching loss rates of DOC and DON,except in spring.?3?IM significantly reduced DOC and DON concentrations in spring and DOC concentration in summer.However,the interaction of IM and N deposition increased the DOC and DON concentrations in spring and winter?P < 0.05?.?4?Biochar amendments significantly reduced the loss rates of DOC in spring,autumn and winter,however,there was no significant effect on DON.?5?Biochar amendments may mitigate DOC and DON losses induced by N deposition,but the mitigating effects on DOC and DON was different.Our results demonstrated that N deposition significantly increased the losses of soil DOC and DON in Moso bamboo plantations to some extent.However,management practices and biochar amendments could mitigate the negative effcets induced by N deposition.In addition,the soil DOC and DON losses showed marked seasonal variation.Therefore,management practices and seasonal variation should be considered when estimating the effects of N deposition on soil DOC and DON in Moso bamboo plantation ecosystems using ecological models,and biochar application is a potential approach to mitigate the DOC and DON leaching loss induced by increasing atmospheric N deposition.