CO2 from urea fertilizer applications
Methods 5.0
Introduction
The carbon dioxide (CO2) emissions from urea fertilizers are directly proportional to the amount of urea applied (\(M\)) and are modulated by the emission factor (\(EF\)) based on the proportion of carbon in urea. Estimating this source of emissions is an addition to version 5 of the Fieldprint Platform.
Methods
Based on Ogle et al. (2024), this method requires data on the amount and type of urea fertilizer applied to soils.
The following equation is used to estimate the total CO2 emissions from urea based fertilizers.
\[ M = \sum_i^n (FR_i \times A \times U^{prop}_i) \]
\[ [CO_2\text{e}]^{total} = M \times EF \times [CO_2\text{e}]^{mw} \]
where
\(FR\) = the annual applied rate of fertilizer ith (kg ha-1)
\(A\) = the area of the field (ha)
\(U^{prop}\) = the proportion of Urea in fertilizer ith [kg urea (kg fertilizer-1)]
\([CO_2\text{e}]^{total}\) = the annual total CO2 emissions (kg CO2e)
\(M\) = the annual Urea application (kg urea)
\(EF\) = the emission factor, based on the proportion of carbon in urea (kg tons CO2-C [kg tons urea]-1)
\([CO_2\text{e}]^{mw}\) = ratio of molecular weight of CO2 to carbon (kg CO2-C [kg C]-1)
Example
The following is a sample of the outputs produced by the method. For illustration purposes, the scenario considered has the following characteristics:
- Setting: Corn field from Story (IA) under conventional tillage
- Field area: 40.5 ha
- Yield: 11,298 kg corn / ha
- Application: 150 kg/ha of Urea and 50 kg/ha of DAP
| System Boundary | kg CO2e | kg CO2e / ha | kg CO2e / kg corn |
|---|---|---|---|
| On-Farm Non-Mechanical Sources and Sinks | 4452 | 110 | 0.01 |