摘要:
采用静态箱 气相色谱法对常规施氮(N2, 525 kg·hm-2)y和减量施氮(N1, 300 kg·hm-2)处理下甘蔗与大豆按行数比1∶1(SB1)和1∶2(SB2)间作、甘蔗单作(MS)、大豆单作(MB)种植模式下蔗田土壤CO2、N2O、CH4排放通量及土地当量比(LER)进行观测和对比分析, 以探讨不同间作模式及施氮水平下甘蔗//大豆间作农田土壤温室气体排放的动态变化规律及对作物产量的影响, 为制定农田温室气体减排措施提供合理的依据。研究结果表明, 减量施氮处理甘蔗//大豆(1∶2)间作模式(SB2-N1)农田土壤CO2排放总量较甘蔗单作(MS)显著降低35.58%, N2O累积排放总量较甘蔗单作降低56.36%, CH4累积排放总量较甘蔗单作升高7.02%; 不同种植模式和施氮处理蔗田土壤均表现为CO2和N2O的排放源, CH4吸收汇, 追施氮肥后土壤对CH4的吸收速率降低, 但CO2和N2O的排放速率增加。MS-N1、SB1-N1、SB2-N1、MS-N2、SB1-N2、SB2-N2和MB处理土壤CO2年累积排放总量(kg·hm-2·a-1)分别为5 096.89、6 422.69、3 283.20、4 103.29、4 475.84、4 775.31和4 780.35, 土壤N2O年累积排放总量(kg·hm-2·a-1)分别为4.61、5.11、2.15、3.13、3.72、5.60和3.11, 土壤CH4年累积排放总量(kg·hm-2·a-1)分别为 13.68、 21.78、 12.72、 5.53、 11.36、 4.77和 9.97。甘蔗//大豆间作系统2009-2012年土地当量比(LER)均大于1, 且减量施氮水平下, 甘蔗//大豆(1∶2)间作模式优势最明显。
Abstract:
This study discussed the effect of different sugarcane intercropping patterns and nitrogen dosages on soils greenhouse gas emission and the related impact on crops yield. The study further strengthened the theoretical basis for measuring agriculture-based greenhouse gas emission. It analyzed emission fluxes of greenhouse gases (CO2, N2O and CH4) in sugarcane//soybean intercropping systems with crops line ratios of 1∶1 (SB1) and 1∶2 (SB2), monocropped sole sugarcane(MS)under two nitrogen levels (N2, 525 kg·hm-2 and N1, 300 kg·hm-2) and monocropped soybean under zero nitrogen supply using the static chamber/gas chromatographic technique during the crop growth season. Results showed that compared to the sugarcane monoculture, cumulative emissions of CO2 and N2O in SB2 under low nitrogen dose (SB2-N1) respectively decreased by 35.58% and 56.36%. Also cumulative CH4 emission increased by 7.02%. Soils in different cropping patterns and nitrogen dosages served as sources of CO2 and N2O, sink of CH4 during crop growth season. After nitrogen application, CH4 absorption rate decreased while CO2 and N2O flux rates increased. CO2 emissions (kg·hm-2·a-1) under MS-N1, SB1-N1, SB2-N1, MS-N2, SB1-N2, SB2-N2 and MB treatments were 5 096.89, 6 422.69, 3 283.20, 4 103.29, 4 475.84, 4 775.31 and 4 780.35, respectively. Cumulative N2O emissions (kg·hm-2·a-1) under MS-N1, SB1-N1, SB2-N1, MS-N2, SB1-N2, SB2-N2 and MB treatments were 4.61, 5.11, 2.15, 3.13, 3.72, 5.60 and 3.11, respectively. Also cumulative CH4 emissions (kg·hm-2·a-1) under MS-N1, SB1-N1, SB2-N1, MS-N2, SB1-N2, SB2-N2 and MB treatments were 13.68, 21.78, 12.72, 5.53, 11.36, 4.77 and 9.97, respectively. Land equivalent ratio (LER) values in sugarcane//soybean intercropping systems exceeded 1.0 during 2009 and 2012. The study showed that SB2 cropping system was the best one under low nitrogen conditions.
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