A Portable Laser Spectroscopic System for Measuring Nitrous Oxide Emissions on Fertilized Cropland.

Area of Science:

• Environmental Science
• Agricultural Science
• Analytical Chemistry

Background:

• Nitrous oxide (N₂O) is a potent greenhouse gas with significant agricultural contributions.
• Nitrogen fertilization is a primary driver of agricultural N₂O emissions.
• Accurate, localized N₂O flux measurements are crucial for emission reduction strategies.

Purpose of the Study:

• To develop and validate a compact, portable system for on-site N₂O emission measurement from croplands.
• To enable precise, real-time monitoring of N₂O fluxes using a novel interband cascade laser (ICL) based tunable laser absorption spectroscopy setup.
• To assess the system's capability in detecting fertilization-induced N₂O emissions and their correlation with environmental factors.

Main Methods:

• Development of a portable tunable laser absorption spectroscopy system utilizing an interband cascade laser (ICL).
• Field validation of the system for measuring N₂O concentrations and fluxes with high precision (3.5%) in short durations (10 min).
• Simultaneous recording of soil moisture, air humidity, and air temperature to analyze their influence on N₂O fluxes.

Main Results:

• The portable ICL-based system achieved a precision of 3.5% for N₂O flux measurements within 10 minutes.
• The system successfully detected increased N₂O emissions immediately following field fertilization, with fluxes ranging from 2.9 to 5.3 µL m^-2 min^-1.
• Observed strong correlations between soil moisture and N₂O fluxes, highlighting the importance of hydrological factors in emission dynamics.

Conclusions:

• The developed portable N₂O measurement system offers a robust, low-power, and field-deployable solution for monitoring agricultural emissions.
• This technology facilitates routine screening of N₂O emissions, supporting targeted fertilizer management to mitigate greenhouse gas output.
• The system's performance is comparable to more complex instruments, paving the way for wider adoption in agricultural research and environmental monitoring.