Modeled and measured ecosystem respiration in maize–soybean systems over 10 years

Crop residue is an abundant resource for the potential production of biofuels, but a better understanding of its use on net carbon emissions must be developed to mitigate climate change. This analysis combines two established crop growth models (Hybrid-Maize and Soysim) with a simple soil and crop residue respiration model to estimate daily ecosystem respiration (ERe) from maize and soybean; ERe was estimated to be the sum of CO2 emissions from the oxidation of the growing crop, crop residue, and soil organic carbon (SOC). Model-estimated CO2 fluxes from irrigated continuous maize and irrigated maize-soybean cropping systems in eastern Nebraska were compared with tower eddy covariance measurements of CO2 fluxes from 2001 to 2010 from those fields. Modeled C emissions closely estimated measured seasonal patterns of CO2 dynamics and measured daily ERe (R2: 0.87, 0.84). Measured and modeled annual ERe values were also compared and better agreement was found in maize compared to soybean. As...

作物残体（Crop residue）是极具开发潜力的生物质燃料生产原料，但为减缓气候变化，仍需更深入理解其使用对净碳排放的影响。本研究将两款成熟的作物生长模型——Hybrid-Maize与Soysim——与简易土壤-作物残体呼吸模型相结合，以估算玉米与大豆的单日生态系统呼吸（Ecosystem Respiration, ERe）；ERe为生长作物、作物残体与土壤有机碳（Soil Organic Carbon, SOC）氧化过程产生的二氧化碳排放量之和。本研究将内布拉斯加州东部灌溉连作玉米田与灌溉玉米-大豆轮作田的模型估算二氧化碳通量，与2001至2010年上述地块通过塔架涡度协方差法测得的二氧化碳通量实测数据进行对比。模拟碳排放量精准匹配了实测的二氧化碳动态季节变化格局与单日生态系统呼吸量（决定系数R²分别为0.87、0.84）。研究同时对比了实测与模拟的年度生态系统呼吸量，结果显示玉米种植系统的模拟结果与实测值吻合度优于大豆系统。As...