Division of Crop Production, Central Rice Research Institute, Cuttack, 753006, Odisha, India.
Sci Total Environ. 2013 Sep 1;461-462:601-11. doi: 10.1016/j.scitotenv.2013.05.035. Epub 2013 Jun 10.
A field experiment was carried out to investigate the impact of elevated carbon dioxide (CO2) (CEC, 550 μmol mol(-1)) and elevated CO2+elevated air temperature (CECT, 550 μmol mol(-1) and 2°C more than control chamber (CC)) on soil labile carbon (C) and nitrogen (N) pools, microbial populations and enzymatic activities in relation to emissions of methane (CH4) and nitrous oxide (N2O) in a flooded alluvial soil planted with rice cv. Naveen in open top chambers (OTCs). The labile soil C pools, namely microbial biomass C, readily mineralizable C, water soluble carbohydrate C and potassium permanganate oxidizable C were increased by 27, 23, 38 and 37% respectively under CEC than CC (ambient CO2, 394 μmol mol(-1)). The total organic carbon (TOC) in root exudates was 28.9% higher under CEC than CC. The labile N fractions were also increased significantly (29%) in CEC than CC. Methanogens and denitrifier populations in rhizosphere were higher under CEC and CECT. As a result, CH4 and N2O-N emissions were enhanced by 26 and 24.6% respectively, under CEC in comparison to open field (UC, ambient CO2, 394 μmol mol(-1)) on seasonal basis. The global warming potential (GWP) was increased by 25% under CEC than CC. However, emissions per unit of grain yield under elevated CO2 and temperature were similar to those observed at ambient CO2. The stimulatory effect on CH4 and N2O emissions under CEC was linked with the increased amount of soil labile C, C rich root exudates, lowered Eh, higher Fe(+2) concentration and increased activities of methanogens and extracellular enzymes.
一项田间试验研究了大气二氧化碳浓度升高（CEC，550 μmol mol(-1)）和二氧化碳浓度升高加空气温度升高（CECT，550 μmol mol(-1)，比对照室高 2°C）对淹水冲积土中种植的水稻品种 Naveen 土壤中易变碳（C）和氮（N）库、微生物种群和酶活性的影响，以及与排放的甲烷（CH4）和氧化亚氮（N2O）的关系。在开放顶罩室（OTC）中，CEC 条件下土壤易变碳库（即微生物生物量 C、易矿化 C、水溶性碳水化合物 C 和重铬酸钾氧化 C）分别比 CC（大气 CO2，394 μmol mol(-1)）增加了 27%、23%、38%和 37%。CEC 条件下根分泌物中的总有机碳（TOC）比 CC 高 28.9%。CEC 条件下易变 N 分数也比 CC 显著增加（29%）。根际甲烷菌和反硝化菌的数量在 CEC 和 CECT 条件下较高。因此，CEC 条件下 CH4 和 N2O-N 的排放分别比 OC 增加了 26%和 24.6%。CEC 条件下的全球变暖潜势（GWP）比 CC 增加了 25%。然而，在升高的 CO2 和温度下，每单位谷物产量的排放量与在大气 CO2 下观察到的排放量相似。CEC 条件下对 CH4 和 N2O 排放的刺激作用与土壤易变 C、富含 C 的根分泌物、降低的 Eh、较高的 Fe(+2)浓度和增加的甲烷菌和胞外酶活性有关。
