为了解农田土壤一氧化氮(NO)周年排放特征,对高原气候区青藏高原东缘种植饲草(燕麦)农田NO排放通量和主要环境因子进行了周年连续定量研究,施肥(F)和不施肥处理(UF)周年累积排放量分别为0.80±0.06 kg N·hm^(-2)?a-1和0.18...为了解农田土壤一氧化氮(NO)周年排放特征,对高原气候区青藏高原东缘种植饲草(燕麦)农田NO排放通量和主要环境因子进行了周年连续定量研究,施肥(F)和不施肥处理(UF)周年累积排放量分别为0.80±0.06 kg N·hm^(-2)?a-1和0.18±0.04 kg N·hm^(-2)?a-1,翻耕施肥期和冻融期NO排放显著贡献了全年累积排放量(F和UF分别为85%和65%)。土壤温度、湿度、无机氮和水浸提有机碳含量显著影响NO排放通量的季节变化,采用土壤湿度、铵态氮、硝态氮和水浸提有机碳含量作为指前因子的指数方程拟合这些土壤变量对NO通量的影响,决定系数高达92%,能够很好地表征碳氮底物有效性、微生物活性和氧气有效性(土壤温度和湿度)对NO排放的协同效应,由此得到NO排放通量对表层(5 cm)土壤温度的敏感性指数(Q10)值为2.4(F)和2.5(UF),这意味着全球增温对NO排放的促进效应将远低于施肥量增加对NO排放的促进作用。该燕麦农田NO直接排放因子为0.93%±0.10%,有别于其他区域、全国和全球的平均状况,因此不宜采用缺省排放因子计算高原气候区粗放管理方式下农田NO排放清单。考虑到青藏高原地区降水量存在巨大的年际变幅,未来应加强典型农田NO排放的多年际连续观测研究。展开更多
Nitric oxide(NO)emissions from alpine ecosystems conventionally being long-term cultivated with feed crops are not well quantified.The authors attempted to address this knowledge gap by performing a year-round experim...Nitric oxide(NO)emissions from alpine ecosystems conventionally being long-term cultivated with feed crops are not well quantified.The authors attempted to address this knowledge gap by performing a year-round experimental campaign in the northeastern Tibetan Plateau.Fertilized(F)and unfertilized(UF)treatments were established within a flat calcareous-soil site for the long-term cultivation of feed oats.NO fluxes and five soil variables were simultaneously measured.A single plow tillage accounted for approximately 54%–73%of the NO releases during the cropping period(CP);and the non-cropping period(NCP)contributed to 51%–58%of the annual emissions.The direct NO emissions factor(EFd)was 0.021%±0.021%.Significantly lower Q10 values(p<0.01)occurred in the F treatment during the CP(approximately 3.6)compared to those during the other period or in the other treatment(approximately 4.9?5.1),indicating a fertilizer-induced reduction in the temperature sensitivity.The selected soil variables jointly accounted for up to 72%(p<0.01)of the variance for all the fluxes across both treatments.This finding suggests that temporally and/or spatially distributed fluxes from alpine calcareous-soil ecosystems for feed crop production may be easily predicted if data on these soil variables are available.Further studies are needed to test the hypothesis that the EFd is larger in alpine feed-oat fields than those in this study if the soil moisture content is higher during the period following the basal application of ammoniumor urea-based fertilizer.展开更多
文摘为了解农田土壤一氧化氮(NO)周年排放特征,对高原气候区青藏高原东缘种植饲草(燕麦)农田NO排放通量和主要环境因子进行了周年连续定量研究,施肥(F)和不施肥处理(UF)周年累积排放量分别为0.80±0.06 kg N·hm^(-2)?a-1和0.18±0.04 kg N·hm^(-2)?a-1,翻耕施肥期和冻融期NO排放显著贡献了全年累积排放量(F和UF分别为85%和65%)。土壤温度、湿度、无机氮和水浸提有机碳含量显著影响NO排放通量的季节变化,采用土壤湿度、铵态氮、硝态氮和水浸提有机碳含量作为指前因子的指数方程拟合这些土壤变量对NO通量的影响,决定系数高达92%,能够很好地表征碳氮底物有效性、微生物活性和氧气有效性(土壤温度和湿度)对NO排放的协同效应,由此得到NO排放通量对表层(5 cm)土壤温度的敏感性指数(Q10)值为2.4(F)和2.5(UF),这意味着全球增温对NO排放的促进效应将远低于施肥量增加对NO排放的促进作用。该燕麦农田NO直接排放因子为0.93%±0.10%,有别于其他区域、全国和全球的平均状况,因此不宜采用缺省排放因子计算高原气候区粗放管理方式下农田NO排放清单。考虑到青藏高原地区降水量存在巨大的年际变幅,未来应加强典型农田NO排放的多年际连续观测研究。
基金jointly financed by the Ministry of Science and Technology of China(Grant No.2016YFA0602303)the National Natural Science Foundation of China(Grant Nos.41775141,41375152,and 41603075)
文摘Nitric oxide(NO)emissions from alpine ecosystems conventionally being long-term cultivated with feed crops are not well quantified.The authors attempted to address this knowledge gap by performing a year-round experimental campaign in the northeastern Tibetan Plateau.Fertilized(F)and unfertilized(UF)treatments were established within a flat calcareous-soil site for the long-term cultivation of feed oats.NO fluxes and five soil variables were simultaneously measured.A single plow tillage accounted for approximately 54%–73%of the NO releases during the cropping period(CP);and the non-cropping period(NCP)contributed to 51%–58%of the annual emissions.The direct NO emissions factor(EFd)was 0.021%±0.021%.Significantly lower Q10 values(p<0.01)occurred in the F treatment during the CP(approximately 3.6)compared to those during the other period or in the other treatment(approximately 4.9?5.1),indicating a fertilizer-induced reduction in the temperature sensitivity.The selected soil variables jointly accounted for up to 72%(p<0.01)of the variance for all the fluxes across both treatments.This finding suggests that temporally and/or spatially distributed fluxes from alpine calcareous-soil ecosystems for feed crop production may be easily predicted if data on these soil variables are available.Further studies are needed to test the hypothesis that the EFd is larger in alpine feed-oat fields than those in this study if the soil moisture content is higher during the period following the basal application of ammoniumor urea-based fertilizer.
