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为评价土壤呼吸对施氮的响应,于2008年3月~2009年3月,监测了黄土旱塬区长期不同施氮水平条件下小麦连作系统中土壤呼吸日变化、季节变化以及不同生育期土壤可溶性碳(dissolved organic C,DOC)、微生物量碳(soil microbial biomassC,MBC)、土壤有机碳(soil organic C,SOC)和土壤全氮(soil total N,STN)的含量变化.研究涉及5个施氮水平(以N计)0(N0)、45(N45)、90(N90)、135(N135)和180(N180)kg/hm2.结果表明,施氮量为0~90 kg/hm2时,土壤呼吸速率随施氮量的增加而显著升高;90~135 kg/hm2时,土壤呼吸速率随施氮量的增加略有增加;135~180 kg/hm2时,随着施氮量的增加土壤呼吸呈降低趋势.在一年监测期间,N0、N45、N90、N135、N180波动范围(以CO2计)分别为0.27~2.01、0.36~2.26、0.58~2.56、0.65~2.94和0.58~2.6μmol/(m2.s).在季节变化尺度上,土壤呼吸具有显著的活跃期(3~10月)和微弱期(11月~次年2月).施氮显著影响DOC、MBC含量变化.土壤呼吸速率与DOC、MBC呈显著正相关,而与土壤碳氮比(C/N)呈显著负相关关系.
In order to evaluate the response of soil respiration to nitrogen application, the diurnal changes of soil respiration, seasons and the growth of soil at different growth stages under continuous nitrogen fertilization in the Loess Plateau were monitored from March 2008 to March 2009. The contents of dissolved organic carbon (DOC), soil microbial biomass C (MBC), soil organic carbon (SOC) and total soil total nitrogen (NOS) N application rates were 0 (N0), 45 (N45), 90 (N90), 135 (N135) and 180 (N180) kg / hm2, respectively.The results showed that nitrogen application rate was 0 ~ 90 kg / hm2 , And the soil respiration rate increased significantly with the increase of nitrogen application rate. At 90 ~ 135 kg / hm2, the soil respiration rate increased slightly with the increase of nitrogen application rate. With the increase of nitrogen application rate of 135 ~ 180 kg / hm2, During the monitoring period of one year, the fluctuation range of N0, N45, N90, N135 and N180 (calculated by CO2) were 0.27 ~ 2.01,0.36 ~ 2.26,0.58 ~ 2.56,0.65 ~ 2.94 and 0.58 ~ 2.6 μmol / (m2.s) .In the seasonal variation scale, soil respiration had a significant active period (March to October) and a weak period (November to February) .Nitrogen application significantly affected the contents of DOC and MBC. Soil respiration rate DOC, MBC was a significant positive correlation was soil carbon and nitrogen ratio (C / N) with a significant negative correlation.