Effects of long-term conservation tillage on N2 and N2O emission rates and N2O emission microbial pathways in Mollisols

Jinxi Zhao; Yanyu Hu; Wanjing Gao; Huaihai Chen; Miaoyin Yang; Zhi Quan; Yunting Fang; Xin Chen; Hongtu Xie; Hongbo He; Xudong Zhang; Caiyan Lu

doi:10.1016/j.scitotenv.2023.168440

Effects of long-term conservation tillage on N₂ and N₂O emission rates and N₂O emission microbial pathways in Mollisols

Sci Total Environ. 2024 Jan 15:908:168440. doi: 10.1016/j.scitotenv.2023.168440. Epub 2023 Nov 11.

Authors

Jinxi Zhao¹, Yanyu Hu², Wanjing Gao³, Huaihai Chen⁴, Miaoyin Yang¹, Zhi Quan⁵, Yunting Fang⁵, Xin Chen⁶, Hongtu Xie⁶, Hongbo He⁶, Xudong Zhang⁶, Caiyan Lu⁷

Affiliations

¹ Key Laboratory of Pollution Ecology and Environment Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; University of Chinese Academy of Sciences, Beijing 100039, China.
² Key Laboratory of Pollution Ecology and Environment Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
³ University of Chinese Academy of Sciences, Beijing 100039, China.
⁴ State Key Laboratory of Biocontrol, School of Ecology, Sun Yat-sen University, Guangzhou 510006, China. Electronic address: chenhh68@mail.sysu.edu.cn.
⁵ Key Laboratory of Stable Isotope Techniques and Applications, Liaoning 110016, China.
⁶ Key Laboratory of Pollution Ecology and Environment Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; Key Laboratory of Conservation Tillage and Ecological Agriculture, Liaoning 110016, China.
⁷ Key Laboratory of Pollution Ecology and Environment Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; Key Laboratory of Terrestrial Ecosystem Carbon Neutrality, Liaoning 110016, China; Key Laboratory of Stable Isotope Techniques and Applications, Liaoning 110016, China. Electronic address: microyan76@126.com.

PMID: 37952674
DOI: 10.1016/j.scitotenv.2023.168440

Abstract

Conservation tillage is widely used in farmland management for soil carbon sequestration, but it can also lead to potential emissions of nitrous oxide (N₂O). Therefore, our study is aimed to investigate the effects of 15 years of no-tillage combined with four straw mulching levels of 0 % (NT0), 33 % (NT33), 67 % (NT67), and 100 % (NT100) compared to ridge tillage (RT) on the rates of N₂O and N₂ emissions and the respective contributions of four microbial pathways to N₂O emissions. The incubation experiments were conducted at two different moisture levels (55 % and 100 % WFPS) by using dicyandiamide inhibition and ¹⁵N-labeling techniques. Soil samples were collected from the 0-20 cm and 20-40 cm soil depths across three maize growth stages: seedling, jointing, and maturity. Our results showed that conservation tillage significantly decreased the N₂O + N₂ emission at 55 % WFPS, but it has a reverse influence in N₂O + N₂ emission at 100 % WFPS. The proportion of N₂O in gaseous N loss were higher at 100 % WFPS than at 55 % WFPS. Among the four microbial pathways for N₂O emissions, autotrophic nitrification was the dominant pathway 55 %WFPS. The contribution of autotrophic nitrification remarkably decreased, co-denitrification and denitrification increased at 100 %WFPS. Overall, at 100 % WFPS, N₂O emissions from all major microbial pathways were positively correlated with GWC, temperature, TC, TN, NH₄⁺-N, and NO₃^--N, but negatively correlated with soil pH and C/N ratios. Our results suggest that long-term conservation tillage increases N₂O and N₂ emissions from the soil under water-saturated conditions by regulating soil nutrient levels, soil moisture, and microbial pathways. Therefore, we should consider the impact of conservation tillage on N₂O emission risk when we attach importance to the role of conservation tillage in improving soil quality and increasing crop yields.

Keywords: (15)N labeling; Conservation tillage; Gaseous nitrogen loss; Microbial pathways; Nitrous oxide emissions.

MeSH terms

Agriculture / methods
Farms
Fertilizers / analysis
Nitrification*
Nitrous Oxide / analysis
Soil*
Water

Substances

Soil
Nitrous Oxide
Water
Fertilizers