沼液替代化肥对小麦-玉米轮作温室气体排放及温室效应的影响

本文采用密闭箱-气相色谱法研究不同沼液灌溉模式,小麦-玉米轮作条件下温室气体的排放特征,并运用全球增温潜势(GWP)和气体排放强度(GHGI)对小麦-玉米排放的温室效应进行估算。研究表明,在冬小麦-夏玉米轮作周期中,以清/沼比2∶1配比的沼液灌溉,小麦灌3次,玉米灌溉1次的处理(T3)和小麦灌溉4次,玉米灌溉1次的处理(T4)与常规施肥(CF)相比,GWP连续两年没有显著性差异,T3、T4和CF在2016年的GWP为2 990.82±285.00、3 235.48±307.05、3 047.35±315.11;T3、T4和CF在2017年的GWP为2 865.61±296.44、3 069.10±318.44和2 741.70±284.37。但小麦季灌溉1次,玉米灌溉1次处理(T1)和与小麦灌溉2次,玉米灌溉1次的处理(T2)的GWP比CF处理相比显著降低。T1和T2处理在2016年和2017年的GWP分别为2 578.57±279.39、2 586.13±263.01;2 702.59±300.75、2 733.19±260.81,T1和T2处理2016年比CF处理降低了15.38%和11.31%;2017年比CF处理降低了5.67%和0.31%。针对产量进行分析,T2、T3、T4和CF处理连续两年差异性不显著,其中T4处理在2016年产量比CF处理提高了4.12%。T3、T4的温室气体排放强度与常规施肥处理(CF)连续两年差异性不显著,2016年T1和T2处理与CF处理相比显著降低了0.56%,2017年T2处理和CF处理相比差异性不显著。综合考虑GWP与作物产量的因素,T2处理(小麦季2∶1沼液灌溉2次,玉米季2∶1沼液灌溉1次,施氮量为315 kg·hm~(-2))为最优选择,所以T2处理是可以替代化肥且较合理的灌溉模式。

Effects of biogas slurry substituting fertilizer on greenhouse gas emission and greenhouse effect of wheat-corn crop rotation

Greenhouse gas emissions under biogas slurry irrigation from the wheat-maize rotations were measured in situ using the method of static chambers and gas chromatographic techniques, and the greenhouse effects were assessed by using Global Warming Potential (GWP) and Greenhouse Gas Emissions Intensity (GHGI). The results showed that during winter wheat-summer maize rotation period, the GWP of T3 (3 times in wheat season and 1 time in maize season of 2:1 biogas slurry irrigation) and T4 (4 times in wheat season and 1 time in maize season of 2:1 biogas slurry irrigation) for the year 2017 were not significantly different from those for the year 2016 unlike the GWP with conventional fertilization (CF). The GWP of T3, T4 and CF in 2016 were 2 990.82±285.00, 3 235.48±307.05, 3 047.35±315.11, respectively; while, the GWP of T3, T4 and CF in 2017 were 2 865.61±296.44, 3 069.10±318.44, 2 741.70±284.37, respectively. But the GWP was significantly reduced by T1 (1 time in wheat season and 1 time in maize season of 2:1 biogas slurry irrigation) and T2 (2 times in wheat season and 1 time in maize season of 2:1 biogas slurry irrigation) treatments compared with the GWP by CF treatment.The GWP of T1 and T2 in 2016 and 2017 were 2 578.57±279.39 and 2 586.13±263.01; 2 702.59±300.75 and 2 733.19±260.81 respectively. Compared with CF, T1 and T2 treatment reduced GWP by 15.38% and 11.31% in 2016 and by 5.67% and 0.31% in 2017. In terms of yield analysis, T2, T3, T4 and CF treatment did not show significant difference in two consecutive years, the yield of T4 treatment was 4.12% higher than that of CF treatment in 2016.The GHGI of T3, T4 and CF treatments were not significantly different for two consecutive years. Compared with CF treatment, the GHGI by T1 and T2 treatments significantly decreased by 0.56% in 2016, while T2 and CF treatments had shown no significant difference in 2017. Comprehensively, with the consideration of GWP and crop yield factors, the T2 treatment (2 times in wheat season and 1 time in maize season of 2:1 biogas slurry irrigation, and 315 kg·hm^-2) might be the optimal choice. Therefore, T2 treatment is a reasonable irrigation mode instead of the application of chemical fertilizer.