Abstract: 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.

Key words: urban river survey, stretch scale, stretch habitat quality index, Taihu Lake Basin