冬小麦夏玉米农田土壤呼吸与碳平衡的研究

为探讨不同农作措施下的农田碳平衡规律,研究农田对大气CO2的“源”、“汇”特征,2000年至2003年连续测定了不同秸秆管理、灌溉和氮肥施用等种植措施下华北冬小麦、夏玉米生长季的土壤呼吸。结果表明,农田CO2释放主要受气温、土壤水分状况和有机物投入量等因素的影响。秸秆还田与优化灌溉增加了土壤呼吸的强度,不同农作措施间土壤呼吸的差异主要发生在冬小麦生长季。对农田碳平衡研究的计算结果显示,农田系统在常规种植措施下表现为大气CO2的“汇”。在传统农作措施下,华北冬小麦、夏玉米生长季植物碳净固定量(NPP)与土壤碳排放量(Rm)的比值分别为1.16、1.21。

Soil Respiration and Carbon Balance in Winter Wheat and Summer Maize Fields

CO2 evolution of soil in winter wheat-summer maize rotation system was measured in North China plain, and the measuring time for winter wheat was from 2000 to 2002, for summer maize was in 2001 and 2003. The effects of different straw management, irrigation and nitrogen application strategies on soil CO2 efflux were analyzed. The results showed that air temperature, soil water content and the amount of organic materiel that was returned to soil were the three main factors affecting the soil CO2 efflux. Straw returning to the soil after harvest and optimized irrigation method could increase the soil CO2 emission. The differences in soil CO2 evolution among different treatments existed mainly in winter wheat. The carbon budgets in the field showed that the plant-soil systems of winter wheat and summer maize were the "pool" of the atmosphere CO2 under normal planting strategies. Under traditional planting strategies in North China plain, the ratio of net plant sequestrated carbon and soil efflux carbon (NPP/Rh) for winter wheat and summer maize were 1.16, 1.21 respectively.