Source partitioning and emission factor of nitrous oxide during warm and cold cropping seasons from an upland soil in South Korea

Muhammad Ashraful Alam; Muhammad Israr Khan; Song Rae Cho; Ji Yeon Lim; Hyun Ji Song; Pil Joo Kim; Suvendu Das

doi:10.1016/j.scitotenv.2019.01.249

Source partitioning and emission factor of nitrous oxide during warm and cold cropping seasons from an upland soil in South Korea

Sci Total Environ. 2019 Apr 20:662:591-599. doi: 10.1016/j.scitotenv.2019.01.249. Epub 2019 Jan 22.

Authors

Muhammad Ashraful Alam¹, Muhammad Israr Khan², Song Rae Cho¹, Ji Yeon Lim¹, Hyun Ji Song¹, Pil Joo Kim³, Suvendu Das⁴

Affiliations

¹ Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, South Korea.
² Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju 660-701, South Korea.
³ Division of Applied Life Science, Gyeongsang National University, Jinju 660-701, South Korea; Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju 660-701, South Korea. Electronic address: pjkim@gnu.ac.kr.
⁴ Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju 660-701, South Korea. Electronic address: suvendu.bls@gmail.com.

PMID: 30699379
DOI: 10.1016/j.scitotenv.2019.01.249

Abstract

Nitrous oxide (N₂O) is a major greenhouse gas (GHG) with high global warming potential. A majority of the N₂O flux comes from agricultural sources, mainly due to nitrogen (N) fertilization. The soil N₂O flux, induced by N fertilization, mainly originated from two different sources, i.e., fertilizer and soil organic nitrogen (SON). It is essential to know the individual contribution of these two different sources in total N₂O flux for planning necessary mitigation strategies. It is also indispensable to know the seasonal difference of emission factors (EF) for having more accurate N₂O inventory. Therefore, an experiment was conducted in a South Korean upland soil during summer and winter seasons using ¹⁵N labeled urea as an artificial N source and source specific N₂O emissions were distinguished under different environmental conditions. To characterize the N₂O emissions from urea, 0, 50, 100 and 200% of the Korean N recommendation rate was selected for specified crops. The Korean N recommendation rate for red pepper (Capsicum annuum) and garlic (Allium sativum) was 190 and 250 kg N ha^-1, respectively. Direct emissions from urea were estimated from the difference of ¹⁵N₂O flux emitted from ¹⁵N-urea treated soil and the natural abundance of ¹⁵N₂O. From total N₂O fluxes, urea originated N₂O flux was 0.87% and 0.13% of the applied N in warm and cold seasons, respectively and the rest comes from SON. Nitrous oxide EF in the warm season was 2.69% of applied N and in the cold season that was 0.25%. Nitrous oxide fluxes showed a significant exponential relationship with soil temperature. The results show the necessity of considering the different N₂O EF for warm and cold cropping seasons to reduce uncertainty in N₂O inventory. The findings of this research may help better understand N₂O source partitioning and the emission budget from warm and cold cropping seasons.

Keywords: (15)N labeled urea; Natural abundance; Nitrous oxide; Soil organic nitrogen.