Reducing N2O emissions with enhanced efficiency nitrogen fertilizers (EENFs) in a high-yielding spring maize system

Xiaodong Lyu; Ting Wang; Xiaotong Song; Chuanyan Zhao; Robert M Rees; Zhan Liu; Ju Xiaotang; Kadambot H M Siddique

doi:10.1016/j.envpol.2020.116422

Reducing N₂O emissions with enhanced efficiency nitrogen fertilizers (EENFs) in a high-yielding spring maize system

Environ Pollut. 2021 Jan 4:273:116422. doi: 10.1016/j.envpol.2020.116422. Online ahead of print.

Authors

Xiaodong Lyu¹, Ting Wang², Xiaotong Song³, Chuanyan Zhao⁴, Robert M Rees⁵, Zhan Liu⁶, Ju Xiaotang⁷, Kadambot H M Siddique⁸

Affiliations

¹ School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, China; Key Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou Jiaotong University, Lanzhou, 730070, China.
² Institute of Soil, Fertilizer and Water-saving Agriculture, Gansu Academy of Agricultural Sciences, Lanzhou, 730070, China.
³ College of Tropical Crops, Hainan University, Haikou, 570228, China.
⁴ College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730030, China.
⁵ SRUC, West Mains Rd. Edinburgh, EH9 3JG, Scotland, UK.
⁶ Gansu Key Laboratory for Environmental Pollution Prediction and Control, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou, 730030, China.
⁷ College of Tropical Crops, Hainan University, Haikou, 570228, China. Electronic address: juxt@cau.edu.cn.
⁸ The UWA Institute of Agriculture and School of Agriculture & Environment, The University of Western Australia, Perth, WA, 6001, Australia.

PMID: 33445127
DOI: 10.1016/j.envpol.2020.116422

Abstract

Enhanced efficiency nitrogen fertilizers (EENFs), including nitrification inhibitors (NIs) and slow-release fertilizer (SRF), are considered promising approaches for mitigating nitrous oxide (N₂O) emissions while improving crop yield. This study investigated the combined application of EENFs with improved water and fertilizer management in an intensively irrigated spring maize rotation over five years in Northwestern China. High-frequency measurements of N₂O fluxes were made throughout each year (both during crop growth and the fallow season) in five treatments: no N fertilizer as a control (CK), conventional N fertilization and irrigation (Con), optimum N fertilization and irrigation (Opt, 33% reduction in N fertilizer and 25% reduction of irrigation water), optimum N fertilization and irrigation with nitrification inhibitor (Opt + NI), and optimum N fertilization and irrigation with slow-release fertilizer (Opt-SRF). Annual mean cumulative N₂O emissions reached 0.31 ± 0.07, 3.66 ± 0.19, 1.87 ± 0.16, 1.23 ± 0.13, and 1.61 ± 0.16 kg N₂O-N ha^-1 for CK, Con, Opt, Opt + NI, and Opt-SRF, respectively, with annual mean nitrogen use efficiency (NUE) of 36, 54, 61 and 59% for Con, Opt, Opt + NI, and Opt-SRF, respectively. The Opt, Opt + NI and Opt-SRF treatments significantly reduced cumulative N₂O emissions by 49%, 66%, and 56% (P < 0.05), respectively, and increased NUE by 51%, 70%, and 66% (P < 0.05), respectively, relative to Con. However, mean above-ground N uptake (288-309 kg N ha^-1) and mean grain yields (12.7-12.8 Mg ha^-1) did not differ significantly between the Con, Opt, Opt + NI, and Opt-SRF treatments during the five-year study. High N₂O emissions mainly occurred within a few days of fertilization with irrigation, which could have been produced by microbially-mediated nitrifier or nitrifier denitrification processes. The fallow seasons had significantly lower cumulative N₂O emissions, which were mainly attributed to the low temperature, low N inputs of crop residues, and low soil moisture conditions. Our study clearly indicated that the combined application of EENFs with optimum N fertilization and irrigation management can reduce environmental impacts while maintaining high crop yields in dryland regions such as Northwest China.

Keywords: China; Enhanced efficiency nitrogen fertilizers (EENFs); N(2)O emission; Nitrification inhibitors (NIs); Slow-release fertilizer (SRF); Spring maize.