Urea-based nitrogen fertilization in agriculture: a key source of N₂O emissions and recent development in mitigating strategies

ABSTRACT

Agricultural land occupies nearly half of the earth’s surface, and farming activities account for nearly 60% of total anthropogenic N₂O emissions. The manufactured nitrogen (N) fertilizers applied to soils are major sources of N₂O emissions from agricultural systems. Among the synthetic N fertilizers, urea has the highest nitrogen content of all solid nitrogenous fertilizers and accounts for 66% of global synthetic N fertilizer use. Hence, efficient urea-N management is imperative for global N₂O abatement. This review provides an update on advances in N₂O-generating pathways, microbial mechanisms, abiotic and biotic regulating factors, and mitigation strategies. Nitrification inhibitors have been extensively studied as strategies to mitigate soil N₂O emissions by decreasing nitrification and denitrification processes. Controlled/slow-release fertilizer formulations have been used widely to enhance fertilizer N use efficiency by regulating the release rates of N from fertilizer. Additionally, biochar, microbial inoculation with arbuscular mycorrhizal fungi (AMF), biological nitrification inhibitors (BNIs) and biological denitrification inhibitors (BDIs) may enable the development of novel and environment‐friendly strategies for practicable N₂O mitigation in future.

KEYWORDS:

• Agricultural soils
• urea
• N₂o emissions
• biological techniques

Acknowledgements

This work was supported by the [National Natural Science Foundation of China] under Grant [Numbers 41525002, 41877051, 41761134085]; [National Key R & D Program of China] under Grant [Number 2017YFD0200102], and [Ningbo Municipal Science and Technology Bureau] under Grant [Number 202002N3079].

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the fundingNational Natural Science Foundation of China;Ningbo Municipal Bureau of Science and Technology;the National Key R & D Program of China;