作 者 ：陈雪双 刘娟 姜培坤 周国模 李永夫 吴家森
期 刊 ：植物营养与肥料学报 2014年 20卷 5期 页码：1263-1271
关键词：山核桃；N2O排放；施肥；水溶性有机碳；微生物量碳；
Keywords:Carya cathayensis, N2O flux, fertilization, water soluble organic carbon, microbial biomass carbon,
摘 要 ：【目的】N2O是重要的温室气体，其增温潜势是CO2的298倍，而且破坏臭氧层。森林生态系统是陆地生态系统的重要组成部分，占全球陆地面积的33%，森林土壤N2O排放对全球气候变化有重大的影响。山核桃（Carya cathayensis）是非常重要的经济林，是山核桃主产区农民的主要经济来源。近年来，农民采取施用无机肥和有机肥等措施来提高山核桃产量，但施肥对山核桃林地土壤N2O排放的影响尚不清楚，本文以不施肥作为对照（CK），研究单施有机肥(Organic fertilizer, OF)、单施化肥(Inorgnaic fertilizer, IF)、 有机无机肥配施(Organic fertilizer and Inorgnaic fertilizer, OIF)对山核桃林地土壤N2O气体排放的影响。【方法】 利用静态箱-气相色谱法对山核桃林地土壤N2O排放通量进行了为期1年的测定。采样箱为组合式，即由底座、顶箱组成，均用PVC板做成，面积为30 cm×30 cm，高度为30 cm。气体样品采集频率基本为每月1次，采集气体时，将采集箱插入底座凹槽（凹槽内径和深度均为5 cm）中，用蒸馏水密封，分别于关箱后0、 10、 20、 30 min采集，用注射器抽样60 mL置于气袋，带回实验室用岛津GC-2014气相色谱仪进行测定，检测器为电子捕获检测器（ECD），检测器温度为250℃。【结果】 山核桃林地不同施肥土壤N2O排放通量均呈现明显的季节性变化，以夏季最高、冬季最低。土壤N2O的排放通量在N -0.021 ~ 0.161 mg/(m2 ·h)之间变化，不同处理土壤N2O年累积排放量依次为单施有机肥>单施化肥>有机无机肥配施>对照，对应值分别为N 2.17、 2.01、 1.94和0.94 kg/（hm2·a）。与对照相比，施肥处理显著增加N2O的排放（P<0.05），但是各施肥处理N2O排放量之间的差异不显著。单施有机肥和有机无机肥配施处理土壤N2O排放通量与土壤水溶性有机碳含量和微生物量碳呈显著相关关系（P<0.05），而单施化肥和对照则无显著相关性。土壤N2O排放通量与地下5 cm处土壤温度均显著相关（P<0.05），而土壤N2O排放与土壤含水量间没有显著相关性。【结论】 施肥显著促进了山核桃林地土壤N2O排放，不同施肥处理之间山核桃林地土壤N2O排放无显著差异。添加有机肥引起土壤水溶性有机碳和微生物碳的增加可能是有机肥增加山核桃林地土壤N2O排放速率的主要原因之一。
Abstract:N2O fluxes from soil under the Carya cathayensi forest were measured for one year using closed static chamber technique and gas chromatography method. Seasonal variations in N2O flux from managed forestland are related to fertilization and weather conditions. Four different fertilizer treatments with four replicates were set in the field，results showed that N2O fluxes from soil under different fertilization treatments exhibited a strong seasonal pattern, with the maximum values being observed during the summer while the minimum values were observed during the winter. N2O emissions were between -0.021~0.161 mg N/( m2 ·h), the calculated annual emissions of N2O were OF > IF > OIF > CK , 2.17 kg N /（ha·a）>2.01 kg N /（ha·a）>1.94 kg N /（ha·a）>0.94 kg N /（ha·a）. It was interesting to note that fertilization treatments increased significantly the emissions of soil N2O (P <0.05) compared with the control. However no significant difference was observed between the others. Additionally, the content of the WSOC and MBC from the OIF and OF treatment had a significantly correlation with the emissions of the soil N2O (P<0.05), but there was no significantly correlation between the content of the WSOC and MBC from the IF and CK treatment with the emission of the soil N2O. There was a significant positive relationship between soil N2O emission and the soil temperature at 5cm depth. No significant correlation was found between soil N2O flux and soil moisture. In conclusion， the increase of WSOC caused by organic fertilization was probably one of the important reasons for the increase in N2O emission in the soil of Chinese Carya cathayensis stands induced by fertilization.
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