不同留茬高度秸秆还田冬小麦田甲烷吸收及影响因素

    CH4 uptake and its affecting factors in winter wheat field under different stubble height of straw returning

    • 摘要: 为了探讨不同留茬高度的玉米秸秆还田下冬麦田甲烷(CH4)的吸收规律,为评估该地区温室气体排放量与发展循环农业提供依据,该研究基于连续10 a的不同耕作措施进行定位试验,采用静态箱—气相色谱法研究了4种不同玉米秸秆留茬高度还田对冬麦田CH4吸收通量的影响。结果表明:随着秸秆留茬高度即秸秆还田量的增加,麦田CH4吸收通量逐渐减少,表现为秸秆不还田(AS)≈秸秆留茬0.5 m还田(S-0.5)>秸秆留茬1 m 还田(S-1)≈秸秆全量还田(PS),常规耕作不还田处理(AC)和免耕不还田处理(AZ)分别比常规耕作全量还田(PC)和免耕全量还田处理(PZ)高18.3%和15.1%;CH4的吸收通量在小麦整个生育期呈高低相间的三峰曲线,并且与地表温度呈显著的正相关性,与20 cm土层的土壤有机碳含量显著性负相关,与土壤水分相关性不明显;在CH4吸收通量的日变化中,常规和免耕的秸秆全量还田处理白天(6:00-18:00)分别比夜间(18:00-6:00)高18.2%和17.7%,CH4吸收通量与气温、地表温度和20 cm地温有显著的正相关关系。试验表明,常规耕作麦田的CH4吸收通量比免耕要高8.65%。从CH4的吸收和秸秆合理利用的角度来看,常规耕作0.5 m的秸秆留茬高度还田是较合理的还田方式,值得今后推广和应用。

       

      Abstract: Although the straw returning of maize is a main way of straw utilization, the problem of the ecological cycling agriculture and the maize straw comprehensive utilization was faced. The excessively returning of straw not only affected to the afterreap crop growth but also disadvantaged to protect the ecological environment of farmland. The objective of present study was to estimate the flux of CH4 under the different height stubble of straw returning in the North China Plain and determined the optimization height of stubble to balance of CH4 flux and straw returning. The study based on 10 years of tillage and straw management systems with split-plot design, by used the Static Chamber-Gas Chromatographic method, in which included two tillage methods of zero-tillage (ZT) and conventional tillage (CT), and four treatments of stubble returning were total straw returning (PS), 1 m height stubble returning (S-1), 0.5 m height stubble returning (S-0.5) and no straw returning (AS ). The results showed that, the absorption of CH4 decreased with the increase of straw returning, which was the order of AS≈S-0.5>S-1≈PS. The modes of tillage have influence on the absorption of CH4 , the flux of CH4 uptake under AC and AZ were higher 18.3% and 15.1% than PC and PZ respectively. The dynamic changes of CH4 absorption were showed three peaks curve in the whole growth period of wheat, it was lowest in over-winter stage, and highest in anthesis stage. The flux in different growth periods of wheat were related with the surface temperature of soil, and the both had a significant positive correlation, but there had a negative correlation with the content of soil organic carbon at a depth of 20 cm in this study. There was no significant correlation between CH4 uptake and soil moisture content. In diurnal variation of CH4 uptake, the fluxes in daytime under PC and PZ were higher 18.2% and 17.7% than in night, and they significant related with the air temperature, soil surface temperature and soil temperature at a depth of 20 cm. CH4 uptake flux under CT was higher 8.65% than ZT. The treatment of 0.5 m stubble height of straw returning under conventional tillage had higher uptake flux of CH4, and the remaining straw was used for other ways, it is a reasonable straw utilization treatment for global warming potential mitigating and straw comprehensive utilization. Therefore, and we suggest that this treatment be developed in this region.

       

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