秸秆覆盖对冀北山区夏玉米土壤呼吸的影响

摘要

【目的】揭示北方山区秸秆覆盖对旱作玉米田土壤呼吸的影响。【方法】以北方山区夏玉米田为研究对象，采用Li-8100土壤碳通量系统测定了无秸秆覆盖和秸秆覆盖2种条件下土壤呼吸速率的生长季变化特征，分析土壤呼吸速率与水热因子的关系。【结果】在玉米生长季内，土壤呼吸速率呈单峰型变化趋势；秸秆覆盖和无秸秆覆盖的土壤呼吸速率变化范围分别为0.88~2.80μmol/（m2·s）和0.71~1.78μmol/（m2·s），秸秆覆盖土壤呼吸速率显著高于无秸秆覆盖；土壤呼吸与10 cm深处的土壤温度呈显著的指数相关，秸秆覆盖和无秸秆覆盖的土壤温度可以分别解释土壤呼吸变化的82.5%和69.5%；基于土壤温度计算的敏感性指数Q10值为秸秆覆盖（2.94）>无秸秆覆盖（2.18）；土壤呼吸对土壤水分的响应符合一元二次函数模型，无秸秆覆盖和秸秆覆盖的土壤含水率可以解释土壤呼吸变化的88.8%和84.6%；水热双因子模型的拟合结果比单因子模型较差。【结论】秸秆覆盖显著增加了土壤CO2排放，土壤含水率能更好地解释土壤呼吸速率的变化，水热双因子的协同影响机制有待进一步研究。%Objective]The aim of the present study was to explore the effects of straw mulching on soil respiration of maize (Zea mays) cropland in the mountain area in North China.[Method]Soil respira-tion of two treatments (with straw incorporation,TSI and tillage with no straw return,TNS) was measured with Li-8100 carbon efflux system. In addition, the relationships between soil respiration and water and temperature were analyzed.[Results]Changes in soil respiration rates exhibited a single-peaked curve in the two treatments. Soil respiration rates under TSI and TNS were 0.88~2.80 μmol/(m2·s) and 0.71~1.78 μmol/(m2·s),respectively. The pairwise t test showed that soil respiration in the TSI was significantly higher than that in the TNS. Based on exponential function,soil temperature ex plained 82.5% and 69.5% variations of soil respiration in the TSI and in the TNS,respectively. The Q10 of TSI (2.94) was greater than that of TNS (2.18). Soil moisture was related to soil respiration, explaining 88.8% in the TNS and 84.6% in the TSI,respectively.[Conclusion]Straw incorporation increased soil respiration significantly. Quadratic model could well simulate the relationship between soil respiration and soil moisture content. Compared with single-factor equation,two-factor equations (soil tempera-ture and soil moisture) did not improve the explanation of soil respiration to soil temperature and soil moisture content.