土壤温室气体排放对C/N的响应  

Soil greenhouse gases emission in response to the C/N

作　　者：李彬彬[1] 武兰芳[1] LI Bin-bin;WU Lan-fang(Key Laboratory of Ecosystem Network Observation and Modeling,Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China)

机构地区：[1]中国科学院地理科学与资源研究所生态网络观测与模拟重点实验室,北京100101

出　　处：《农业环境科学学报》2018年第9期2067-2078,共12页Journal of Agro-Environment Science

基　　金：国家自然科学基金项目(31271675);国家科技支撑计划课题(2013BAD05B03)~~

摘　　要：土壤碳氮比(C/N)是影响微生物活动导致土壤温室气体排放和养分有效性变化的关键因素,秸秆还田配施氮肥则是调节农田土壤C/N的重要措施。为了探讨土壤C/N对温室气体排放的影响,通过在土壤中添加等量秸秆配以不同数量N素,在室内培养条件下测定分析了土壤不同起始C/N条件下土壤温室气体排放和活性碳氮的变化动态。研究发现:不同C/N条件下,土壤温室气体排放和溶解性有机碳(DOC)、溶解性有机氮(DON)的变化趋势基本一致。土壤CO_2排放速率和DOC含量均表现为随培养时间的延长逐渐降低,培养前30 d下降幅度较大,30~75 d降低缓慢,75 d后基本平稳;土壤N_2O的排放速率和DON含量则表现为先升高后降低,N_2O的排放速率在第7 d达到最大后逐渐降低直至平稳,土壤DON含量在第14 d达到最高后逐渐降低。土壤起始C/N越低,有机碳矿化率和净氮硝化速率越高,CO_2和N_2O排放量越多;土壤CO_2和N_2O的排放速率及累积排放量不但与土壤DOC和DON含量显著相关,而且与土壤DOC/DON比值显著相关。土壤硝态氮的含量变化表现为与土壤起始C/N相关,当土壤起始C/N在20~30时,硝态氮先升高后降低;土壤起始C/N大于40时,硝态氮先降低后升高。结果表明:在实际生产中,秸秆还田后合理配施氮肥调节土壤C/N是减少温室气体排放、提高作物氮肥利用效率的重要措施,为了掌握适宜的配施量和施用时期,有必要针对不同作物农田系统继续进行田间试验研究。The soil C/N is a key factor affecting the emission of greenhouse gases(GHGs)from soil and the nutrient availability,resulting from the microbial activity in soil.The retention of crop residues in soil,combined with the application of N fertilizer,is an important way to adjust the soil C/N.To investigate the effect of the soil C/N on GHGs emission,a batch of incubation experiments with 5 different treatments of C/N were conducted,that ground mature maize stalks and leaves along with urea N were mixed into the pre-incubated soil.The changing trends of soil GHG emissions,the dissolved organic carbon(DOC),and the dissolved organic nitrogen(DON)were observed during the 180 days of incubation.The soil CO2 efflux and the DOC content decreased throughout the incubation period and could be differentiated into 3 phases,the fast decreasing phase before the 30th day,the slow decreasing phase from the 30th to the 75th day,and tended towards a stable phase after the 75th day.Meanwhile,both the soil N2O efflux and DON content had a tendency to increase at first and then decline until keep stable;their peaks were observed on day 7 and day 14,respectively.The lower the soil C/N,the faster was the rate of soil organic C mineralization and N nitrification,consequently increasing CO2 and N2O emissions.The correlation analyses showed that the CO2 and N2O emissions of the soil were not only significantly related with the DOC and DON content,but were also related with the DOC/DON ratio in soils.The nitrate(N)content in the soil was related to the initial soil C/N.However,the changes in the nitrate(N)content in soils with different C/N were different;the changes increased at first and then decreased at low C/N,but the changes were just the opposite when the soil C/N was greater than 40.The results indicate that by adjusting the soil C/N with the correct application of N fertilizer,after crop residue retention in the soil,is a fundamental approach to mitigate GHGs emission and improve soil N availability in farming practices.As for the

关 键 词：C/N 温室气体排放 可溶性有机碳 可溶性有机氮 

分 类 号：X511[环境科学与工程—环境工程]