Reducing CO2 Flux by Decreasing Tillage in Ohio: Overcoming Conjecture with Data

Eash

Zahn

et al. 2019

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Industrial biotechnology waste as a soil amendment approximates farmer practice yields. Applying waste amendments significantly increased soil organic C compared with farmer practice. Using waste nutrients for agriculture and soil organic matter improves sustainability. Reuse of industrial biotechnology by‐products has become an important component of circular bio‐economies whereby nutrient‐rich wastes are returned to agricultural land to improve soil fertility and crop productivity. Heat‐inactivated spent microbial biomass (SMB) from the production of 1,3‐propanediol is an industrial fermentation by‐product with nutrients that could replace or supplement conventional fertilizers. Our objectives were to determine if SMB utilization as a soil amendment in agriculture could generate environmental benefits while meeting farmer yield expectations and assess the impact of SMB application on CO2 emissions. This study examined the replacement of typical farmer fertilizer practices with the application of SMB. In addition to yellow dent maize (Zea mays L. var. indentata) grain yield and aboveground biomass, soil organic carbon (SOC) was measured. The eddy covariance (EC) micrometeorological method was used to measure CO2 flux. Overall maize yields were positively correlated with increasing application rates of SMB. After two SMB applications, SOC increased by 45% on the SMB plot as compared with an increase of 11% on the farmer practice plot. The SMB‐treated plot also emitted more CO2 (794 g CO2 m−2 yr−1) compared with the farmer practice treatment (274 g CO2 m−2 yr−1). Results from this study provide information on the efficacy of waste product nutrient cycling in the soil–plant ecosystem that could improve productivity and sustainability.

Section: Resultsmentioning

confidence: 99%

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

Eash

Zahn

et al. 2019

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“…Five‐second measurements were averaged over successive 5‐min intervals by the BREB systems and used to calculate 30‐min mean CO 2 flux according to BREB system theory (Bowen, 1926; Dugas, 1993; Kanemasu et al, 1979; Tanner, 1960; Webb et al, 1980) using the approach as reported by O'Dell et al (2018). Five‐minute water vapor pressure and temperature differences were averaged over 30‐min intervals to calculate the Bowen ratio, which was then used to calculate latent energy and sensible heat fluxes.…”

Section: Methodsmentioning

confidence: 99%

“…Carbon dioxide flux was calculated according to methods described in O'Dell et al (2018) as the product of the turbulent diffusivity for CO 2 flux (assumed to be equal to K H ) and the average difference of CO 2 density between the two measurement heights. The flux was corrected for vapor pressure and temperature differences at the two measurement heights according to Webb et al (1980).…”

Section: Methodsmentioning

confidence: 99%

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

Eash

Hicks³

et al. 2019

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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.

“…Figure 2 shows the layout of the field site of the Ohio study of 2015 (O'Dell et al., 2018). Above each of two test plots, measurements were made of the concentration of CO 2 in air, the air temperature and vapor pressure at two levels close to the surface, wind speed, and the surface temperature as reported by downward looking infrared thermometers.…”

Section: The Ohio Co2 Studymentioning

confidence: 99%

A statistical approach to surface renewal: The virtual chamber concept

Hicks

Lichiheb

et al. 2021

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In the stable conditions prevailing at night, concentrations of emitted gases (e.g., radon [Rn], carbon dioxide [CO2], methane [CH4], ammonia [NH3], and nitrous oxide [N2O]) build up at the surface, with intermittent interruptions due to the passage of packets of turbulence. The applicability of conventional experimental methods is then questionable. Here, a statistical approach is proposed, in which micrometeorological field data are used to replicate the likely characteristics of a chamber experiment, yielding estimates of surface fluxes at the surface itself with reduced requirement for adequate fetch. Application of the virtual chamber methodology to two recent field studies is explored: (a) a study of nocturnal CO2 emission from a farmland area in Ohio in 2015; and (b) an investigation of NH3 effluxes from a crop previously treated with urea ammonium nitrate (UAN) in Illinois in 2014. For both datasets, the virtual chamber approach yields results in general agreement with eddy covariance (EC) data.