Increasing atmospheric CO2 concentration impacts the terrestrial carbon(C) cycle by affecting plant photosynthesis, the flow of photosynthetically fixed C belowground, and soil C pool turnover. For managed agroecosyst...Increasing atmospheric CO2 concentration impacts the terrestrial carbon(C) cycle by affecting plant photosynthesis, the flow of photosynthetically fixed C belowground, and soil C pool turnover. For managed agroecosystems, how and to what extent the interactions between elevated CO2 and N fertilization levels influence the accumulation of photosynthesized C in crops and the incorporation of photosynthesized C into arable soil are in urgent need of exploration.We conducted an experiment simulating elevated CO2 with spring wheat(Triticum aestivum L.) planted in growth chambers.13C-enriched CO2 with an identical 13C abundance was continuously supplied at ambient and elevated CO2 concentrations(350 and 600 μmol mol-1, respectively) until wheat harvest.Three levels of N fertilizer application(equivalent to 80, 120, and 180 kg N ha-1 soil) were supplied for wheat growth at both CO2 concentrations. During the continuous 62-d 13CO2 labeling period, elevated CO2 and increased N fertilizer application increased photosynthesized C accumulation in wheat by 14%–24% and 11%–20%, respectively, as indicated by increased biomass production, whereas the C/N ratio in the roots increased under elevated CO2 but declined with increasing N fertilizer application levels. Wheat root deposition induced 1%–2.5% renewal of soil C after 62 d of 13CO2 labeling. Compared to ambient CO2, elevated CO2 increased the amount of photosynthesized C incorporated into soil by 20%–44%. However, higher application rates of N fertilizer reduced the net input of root-derived C in soil by approximately 8% under elevated CO2. For the wheat-soil system, elevated CO2 and increased N fertilizer application levels synergistically increased the amount of photosynthesized C. The pivotal role of plants in photosynthesized C accumulation under elevated CO2 was thereby enhanced in the short term by the increased N application. Therefore, robust N management could mediate C cycling and sequestration by influencing the interactions between plants and soil in agroecosystems under elevated CO2.展开更多
Potted rice seedlings independently treated with N,P,and NP were continuously^(13)CO_(2) labeled to investigated the influence of N and P application on the contribution of photosynthesized C to the rhizosphere versus...Potted rice seedlings independently treated with N,P,and NP were continuously^(13)CO_(2) labeled to investigated the influence of N and P application on the contribution of photosynthesized C to the rhizosphere versus bulk soil and particulate organic matter(POM)versus mineral fraction(MIN).N and NP enhanced net assimilated^(13)C on day 14(D14),with maximum C assimilation occurring on day 22(D22)under NP.Aboveground biomass retained more^(13)C than belowground biomass for all treatments.^(13)C incorporation into the rhizosphere exceeded that in bulk soil,with the maximum(6-10%)found under N addition.Newly assimilated^(13)incorporated into POM increased in the rhizosphere under N and NP conditions,whereas MIN remained largely unaffected.^(13)C-MBC proportion in the total microbial biomass C(MBC)pool revealed that N and NP stimulated microbial activity to a greater degree than P.The main portion of^(13)C in the rhizosphere and bulk soil was found in POM on D14,which decreased over time due to microbial utilization.Contrastingly,root-derived ^(13)C in the MIN remained unchanged between sampling days,which indicates that the stabilization of rhizodeposits in this fraction might be the potential mechanism underlying SOM sequestration in paddy soils.展开更多
基金supported by the National Natural Science Foundation of China (No. 41630862)the National Key Research and Development Program (No. 2017YFD0200100)the “China Soil Microbiome Initiative: Function and Regulation of Soil—Microbial Systems” of the Chinese Academy of Sciences (No. XDB15040200)。
文摘Increasing atmospheric CO2 concentration impacts the terrestrial carbon(C) cycle by affecting plant photosynthesis, the flow of photosynthetically fixed C belowground, and soil C pool turnover. For managed agroecosystems, how and to what extent the interactions between elevated CO2 and N fertilization levels influence the accumulation of photosynthesized C in crops and the incorporation of photosynthesized C into arable soil are in urgent need of exploration.We conducted an experiment simulating elevated CO2 with spring wheat(Triticum aestivum L.) planted in growth chambers.13C-enriched CO2 with an identical 13C abundance was continuously supplied at ambient and elevated CO2 concentrations(350 and 600 μmol mol-1, respectively) until wheat harvest.Three levels of N fertilizer application(equivalent to 80, 120, and 180 kg N ha-1 soil) were supplied for wheat growth at both CO2 concentrations. During the continuous 62-d 13CO2 labeling period, elevated CO2 and increased N fertilizer application increased photosynthesized C accumulation in wheat by 14%–24% and 11%–20%, respectively, as indicated by increased biomass production, whereas the C/N ratio in the roots increased under elevated CO2 but declined with increasing N fertilizer application levels. Wheat root deposition induced 1%–2.5% renewal of soil C after 62 d of 13CO2 labeling. Compared to ambient CO2, elevated CO2 increased the amount of photosynthesized C incorporated into soil by 20%–44%. However, higher application rates of N fertilizer reduced the net input of root-derived C in soil by approximately 8% under elevated CO2. For the wheat-soil system, elevated CO2 and increased N fertilizer application levels synergistically increased the amount of photosynthesized C. The pivotal role of plants in photosynthesized C accumulation under elevated CO2 was thereby enhanced in the short term by the increased N application. Therefore, robust N management could mediate C cycling and sequestration by influencing the interactions between plants and soil in agroecosystems under elevated CO2.
基金This work was funded by the National Natural Science Foundation of China[41877104,41950410565,41811540031]Hunan Province Base for Scientific and Technological Innovation Cooperation[2018WK4012]+6 种基金Natural Science Foundation of Hunan Province[2019JJ10003,2019JJ30028]the Youth Innovation Team Project of the Institute of Subtropical Agriculture,Chinese Academy of Sciences[2017QNCXTD_GTD]Talented Young Scientist Program(TYSP)supported by China Science and Technology Exchange Center(CSTEC)the Chinese Academy of Sciences President’s International Fellowship Initiative awarded to Anna Gunina[2019VCC0003]Tin Mar Lynn[2018PC0078]China National Key R&D Program[2019YFC0605004]Jiangxi Province Scienc and Technology Planned Project[20202BBG73007,20203BBG73068].
文摘Potted rice seedlings independently treated with N,P,and NP were continuously^(13)CO_(2) labeled to investigated the influence of N and P application on the contribution of photosynthesized C to the rhizosphere versus bulk soil and particulate organic matter(POM)versus mineral fraction(MIN).N and NP enhanced net assimilated^(13)C on day 14(D14),with maximum C assimilation occurring on day 22(D22)under NP.Aboveground biomass retained more^(13)C than belowground biomass for all treatments.^(13)C incorporation into the rhizosphere exceeded that in bulk soil,with the maximum(6-10%)found under N addition.Newly assimilated^(13)incorporated into POM increased in the rhizosphere under N and NP conditions,whereas MIN remained largely unaffected.^(13)C-MBC proportion in the total microbial biomass C(MBC)pool revealed that N and NP stimulated microbial activity to a greater degree than P.The main portion of^(13)C in the rhizosphere and bulk soil was found in POM on D14,which decreased over time due to microbial utilization.Contrastingly,root-derived ^(13)C in the MIN remained unchanged between sampling days,which indicates that the stabilization of rhizodeposits in this fraction might be the potential mechanism underlying SOM sequestration in paddy soils.
