保护性耕作条件下小麦田甲烷吸收及影响因素

采用静态箱-气相色谱法对保护性耕作和常规耕作小麦田的CH₄排放进行了原位测量，同时测量了土壤温度、水分、无机氮等相关影响因子，以研究保护性耕作农田CH₄排放通量及相关因素的影响.结果表明：保护性耕作及常规耕作麦田CH₄的排放具有明显的季节性变化规律，且变化趋势一致；保护性耕作与常规耕作各处理的CH₄平均吸收通量、季节吸收量差异显著（P<0.05）.在小麦生长季内，各处理农田均表现为CH₄的吸收汇.各处理CH₄季节吸收通量表现为：常规耕作无秸秆还田>常规耕作秸秆还田>深松秸秆还田>耙耕秸秆还田>旋耕秸秆还田>免耕秸秆还田，与常规耕作相比，保护性耕作CH₄吸收通量减少.保护性耕作CH₄吸收通量与温度呈正相关，与水分呈负相关，常规耕作CH₄吸收通量与两因子相关不显著；各处理CH₄吸收通量与NH₄⁺-N含量呈显著负相关.

CH4 absorption and its affecting factors in a wheat field with conservation tillage.

In order to understand the relationships between CH₄ fluxes and its affecting factors in a wheat field with conservation tillage, the CH₄ fluxes in two wheat fields, one with conservation tillage and the another with conventional tillage, were measured in situ by static chamber-GC method, with soil temperature and soil moisture and inorganic nitrogen contents determined at the same time. The results showed that these two fields had an obvious and similar seasonal variation pattern of CH₄ fluxes, but the average and seasonal CH₄ absorption fluxes differed significantly. In the growth period of wheat, the fields were the sink of CH₄, and the CH₄ absorption fluxes was in the order of conventional tillage with no straw returning (CN)>conventional tillage with straw returning (CS)>subsoiling with straw returning (PS)>harrowing with straw returning (HS)>rotary tillage with straw returning (RS)>no tillage with straw covered (NS). Comparing with conventional tillage, conservation tillage reduced the CH₄ absorption fluxes. In conservation tillage, the CH₄ absorption fluxes was positively correlated with soil temperature but negatively correlated with soil moisture content; while in conventional tillage, the CH₄ absorption fluxes had no significant correlations with the two factors. In all treatments, there was a significant negative correlation between CH₄ absorption fluxes and soil NH₄⁺-N content.