Nutrient Source and Tillage Effects on Maize: I. Micrometeorological Methods for Measuring Carbon Dioxide Emissions

Abstract

Core Ideas Aerodynamic methods can be used to gap‐fill Bowen ratio energy balance micrometeorological measurements. Eddy covariance and Bowen ratio energy balance methods agree during turbulent daytime conditions. Measuring nighttime net ecosystem exchange is challenging using turbulence‐based micrometeorology. There is a need to understand the potential benefits of using the biotechnology waste by‐product from manufacturing as a fertilizer replacement in agriculture, by quantifying the economic value for the farmer and measuring the environmental impact. Measuring CO2 emissions can be used to assess environmental impact, including three widely used micrometeorological methodologies: (i) the Bowen Ratio Energy Balance (BREB), (ii) aerodynamic flux‐gradient theory, and (iii) eddy covariance (EC). As a first step in quantifying benefits of applying biotechnology waste in agriculture, a detailed examination of these three methods was conducted to understand their effectiveness in quantifying CO2 emissions for this specific circumstance. The study measured micrometeorological properties over a field planted to maize (Zea mays L. var. indentata), one plot treated with biotechnology waste applied as a nutrient amendment, and one plot treated with a typical farmer fertilizer practice. Carbon dioxide flux measurements took place over 1 yr, using both BREB and EC systems. The aerodynamic method was used to gap‐fill BREB system measurements, and those flux estimates were compared with estimates produced separately by the aerodynamic and EC methods. All methods found greater emissions over the biotechnology waste application. The aerodynamic method CO2 flux estimates were considerably greater than both the EC and a combined BREB‐aerodynamic approach. During the day, the EC and BREB methods agree. At night, the aerodynamic approach detects and accounts for buildup of CO2 at the surface during stable periods. The BREB systems combined with aerodynamic approaches provide alternate methods to EC in examining micrometeorological properties near the surface.

Nutrient Source and Tillage Effects on Maize: II. Yield, Soil Carbon, and Carbon Dioxide Emissions

“…Both eddy covariance (EC) and Bowen ratio energy balance systems were used to measure micrometeorological and soil properties between 1 Oct. 2016 and 30 Sept. 2017 as described in Part 1 of this series (O'Dell et al, 2019). For the purposes of this study, the EC method was selected for comparing the CO 2 emission between the two treatments, though more information describing specific differences observed between these two micrometeorological approaches can be found in O'Dell et al (2019). Eddy covariance stations were located near the center of each plot with the instrument on the FP plot positioned 155 m from the southern edge of the field and 60 m S of the edge of the SMB plot.…”

Applications and prospect of the flux-gradient method in measuring the greenhouse gases and isotope fluxes

“…势是可以进行原位无干扰的连续观测, 而且在单点 上观测的通量信号是通量贡献区内不同位置地面通 量的加权平均 (Baldocchi et al, 1988) (Baldocchi et al, 2001;Baldocchi, 2014 (Simpson et al, 1995(Simpson et al, , 1998Miyata et al, 2000;Griffis et al, 2004;Pattey et al, 2006;Santos et al, 2012;Xiao et al, 2014;Laubach et al, 2016;Karlsson, 2017;O'Dell et al, 2019;Zhao et al, 2019) 的观测研究中。此外, 通量梯度法也被用于其他痕 量气体的通量观测, 如森林内外的H 2 通量 (Meredith et al, 2014)、草地气态汞通量 (Fritsche et al, 2008) 和大气汞循环研究 (Angot et al, 2016 (Baldocchi et al, 1988;Lee, 2018), 在近地边界层内对质量守恒的连 续方程进行一阶闭合假设, 可以得到湍流协方差项, 即湍流通量项等于物质浓度梯度与湍流扩散系数的 乘积 (Baldocchi et al, 1988;Lee, 2018), (Griffis et al, 2004), (Businger, 1986;Meyers et al, 1996), 计算公式为: Businger, 1986;Meyers et al, 1996) (Meyers et al, 1996;Xiao et al, 2014;Zhao et al, 2019)…”