太行山前平原夏玉米-冬小麦轮作生态系统碳截存及其气体调节价值

应用静态明箱-气相色谱法对4个施氮肥水平NO（0kgN·hm^-2），N200（200kgN·hm^-2），N400（400kgN·hm^-2），N600（600kgN·hm^-2）的夏玉米-冬小麦季CH4、N2O排放进行了研究，同时估算了其年季净固碳量及其O2气体调节价值，计算了年综合气体调节价值。结果表明，夏玉米-冬小麦农田生态系统为CH4吸收汇和N2O排放源，随着氮肥施入量的增加，其对CH4吸收能力减弱，其N2O排放量增加。夏玉米季N400和N600的CH4平均排放速率显著高于N0和N200（P〈0．05）；冬小麦季N0处理CH4平均排放速率显著低于N600处理（P〈0．05），冬小麦季N600的N2O平均排放速率显著高于NO处理（P〈0．05）。夏玉米-冬小麦轮作农田生态系统N0、N200、N400和N600处理CH4排放总量分别为-2．55、-1．99、-0．94和0．47kg·hm^-2·a^-1；其N2O排放总量分别为1．05、1．45、1．67和2．22kg·hm^-2·a^-1。随着氮肥施用量的增加，夏玉米季和冬小麦季转化为NPP的碳量和净固碳量均增加；夏玉米-冬小麦轮作农田生态系统N0、N200，N400和N600处理年季净固碳量分别为6224．29，13885．05，14554．35和14521．10kg·hm^2·a^-1；其中N200，N400和N600分别比N0处理增加了123．08％、133．83％和133．30％。夏玉米-冬小麦轮作农田生态系统N0，N200，N400和N600处理综合气体调节价值分别为10560．19、23602．64、24727．78和24634．24yuan·hm^2·a^-1；N200、N400和N600分别比N0处理增加了123．51％、134．16％和133，27％，以N400处理年固碳量最高。

Carbon Sequestrations and Gas Regulations in Summer-Maize and Winter-Wheat Rotation Ecosystem Affected by Nitrogen Fertilization in the Piedmont Plain of Taihang Mountains,China

Nitrous oxide and methane emissions from a rotation ecosystem of summer-maize and winter-wheat were studied by static transparent chamber and gas chromatography technique from July in 2007 to June in 2008. The nitrogen fertilizer application rates were 0（N0）, 200 （N200）, 400（N400） and 600 kg N·hm^-2（N600）, respectively. Simultaneously, the net carbon sequestration, the O2 emission quantity and the economic values of gas regulations per year were calculated. The results showed： summer-maize and winter-wheat cropland ecosystems were the sink of CH4 and source of N2O, respectively. With the increase of nitrogen application, the CHa consumption decreased and the N2O emission increased. The CH4 average flux rates of N400 and N600 were greater than those of NO and N200 during the summer-maize growth period （P〈0.05）. During the winter-wheat growth period, the CH4 and N2O average flux rates of NO all decreased significantly compared with that of N600（P〈0.05 ）. The cumulative CH4 emissions in treatments N0, N200, N400 and N600 were -2.55, -1.99, -0.94 and -0.47 kg·hm^-2·a^-1, respectively; And their cumulative N20 emissions were 1.05, 1.45, 1.67 and 2.22 kg·hm^-2·a^-1, respectively. With increase of nitrogen application, the carbon content of NPP （net primary productivity） and the net carbon sequestration all increased in summer-maize and winter-wheat rotation ecosystem. The net carbon sequestration quantities per year of N0, N200, N400 and N600 were 6 224.29, 13 885.05, 14 554.35 and 14 521.10 kg·hm^-2·a^-1, respectively; And the net carbon sequestrations per year of N200, N400 and N600 increased 123.08%,133.83and 133.30% compared with that of NO, respectively. The economic values of integrated gas regulations per year of N0, N200, N400 and N600 were 10 560.2, 23 602.6, 24 727.8 and 24 634.2 yuan·hm^-2·a^-1, respectively; and compared with the corresponding values of N0, the economic values of integrated gas regulations of N200, N400 and N600 increased 123.51%, 134.16% and 133.2