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Gaseous emissions from an intensive vegetable farm measured with slant-path FTIR technique

Bai, Mei, Suter, Helen, Lam, Shu Kee, Davies, Rohan, Flesch, Thomas K., Chen, Deli
Agricultural and forest meteorology 2018 v.258 pp. 50-55
Fourier transform infrared spectroscopy, ammonia, carbon, carbon dioxide, celery, emissions factor, farms, fertilizer application, gases, greenhouse gas emissions, manure spreading, methane, nitrogen, nitrous oxide, nitrous oxide production, poultry manure, soil, Australia
A recently developed slant-path flux gradient (FG) technique, combined with open-path Fourier transform infrared (OP-FTIR) spectroscopy, was deployed to concurrently measure gas emissions of ammonia (NH3), nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) from an intensive vegetable farm in Australia. Gas fluxes were continuously measured for three weeks following chicken manure application to a celery crop, followed by intermittent measurements for three days a week for another three weeks. The average flux measured over the 41 day measurement period for NH3 and N2O, was 5.2 and 2.9 mg N m−2 h−1, respectively, CH4 was 1.1 mg C m−2 h−1, and CO2 was 0.7 C g m−2 h−1. Manure and fertilizer application substantially increased the emissions of these gases, by providing carbon (C) and nitrogen (N) substrates to the soil. The cumulative N losses as NH3 and N2O following fertilizer application were 6.7% and 3.7% of total N applied, respectively. Using this FG/OP-FTIR technique, we demonstrated that the N2O emission factor for this vegetable farm is much higher than the IPCC default emission factor for manure applied to managed lands. These results highlight the need for large-scale measurements to quantify multiple gas losses from intensive agricultural systems.