为探讨不同农作措施条件下的农田碳平衡规律,研究农田对大气CO_2的源汇特征,2000年至2003年用钠石灰碱吸收法连续测定不同秸秆还田、灌溉和氮肥施用等农作措施下京郊冬小麦—夏玉米轮作体系作物生长季的土壤呼吸。影响农田土壤CO_2释放的环境因素主要有平均气温和土壤水分含量。土壤CO_2的释放量与同时期平均气温具有很好的相关性,两者可用指数函数拟合(不同处理相关系数范同在0.84~0.87),传统农作措施条件下农田土壤呼吸的Q_(10)为2.32;土壤水分含量与同时期土壤CO_2释放量间没有明显的相关关系,但只有在土壤水分和气温同时改善时,土壤CO_2释放量才有较大的提高,当土壤含水量达到31%时土壤呼吸受到抑制。冬小麦、夏玉米生长季测定得到的最大日平均CO_2释放通量是26.4 g CO_2 m~(-2)d~(-1),35.5 g CO_2 m~(-2)d~(-1)。两种作物生长期间均出现两次释放高峰,第一次来源于前茬作物残留于土壤中根系和秸秆的分解;第二次释放高峰出现在冬小麦灌浆期、夏玉米十叶期。不同农作措施下农田CO_2释放总量的范围是3494~4113 g CO_2 m~(-2)a...
【英文摘要】
Soil respiration and carbon balance in the winter wheat-summer maize system were studied in the suburb of Beijing from 2000 to 2003. The soil respirations under different straw management, irrigation and nitrogen application strategies were measured by soda lime absortion technique. The result showed that, Air temperature and soil moisture were two major environmental factors affecting the soil respiration. The CO2 effluxes from the soil showed exponential responses to the air temperature with si...