Carbon and nitrogen fractions control soil N2O emissions and related functional genes under land-use change in the tropics

Qilin Zhu; Lijun Liu; Chengzhi Wang; Yunxing Wan; Ruoyan Yang; Jinxia Mou; Juan Liu; Yanzheng Wu; Shuirong Tang; Tongbin Zhu; Lei Meng; Jinbo Zhang; Ahmed S Elrys

doi:10.1016/j.envpol.2023.122370

Carbon and nitrogen fractions control soil N₂O emissions and related functional genes under land-use change in the tropics

Environ Pollut. 2023 Oct 15:335:122370. doi: 10.1016/j.envpol.2023.122370. Epub 2023 Aug 14.

Authors

Qilin Zhu¹, Lijun Liu¹, Chengzhi Wang¹, Yunxing Wan¹, Ruoyan Yang¹, Jinxia Mou¹, Juan Liu², Yanzheng Wu¹, Shuirong Tang¹, Tongbin Zhu³, Lei Meng⁴, Jinbo Zhang¹, Ahmed S Elrys⁵

Affiliations

¹ College of Tropical Crops, Hainan University, Haikou, 570228, China.
² College of Resource and Environment Science, Yunnan Agricultural University, Kunming, 650201, China.
³ Institute of Karst Geology, Chinese Academy of Geological Sciences, Karst Dynamics Laboratory, MLR and Guangxi, Guilin, 541004, China.
⁴ College of Tropical Crops, Hainan University, Haikou, 570228, China. Electronic address: menglei@hainanu.edu.cn.
⁵ College of Tropical Crops, Hainan University, Haikou, 570228, China; Soil Science Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt; Liebig Centre for Agroecology and Climate Impact Research, Justus Liebig University, Giessen, Germany.

PMID: 37586684
DOI: 10.1016/j.envpol.2023.122370

Abstract

Converting natural forests to managed ecosystems generally increases soil nitrous oxide (N₂O) emission. However, the pattern and underlying mechanisms of N₂O emissions after converting tropical forests to managed plantations remain elusive. Hence, a laboratory incubation study was investigated to determine soil N₂O emissions of four land uses including forest, eucalyptus, rubber, and paddy field plantations in a tropical region of China. The effect of soil carbon (C) and nitrogen (N) fractions on soil N₂O emissions and related functional genes was also estimated. We found that the conversion of natural forests to managed forests significantly decreased soil N₂O emissions, but the conversion to paddy field had no effect. Soil N₂O emissions were controlled by both nitrifying and denitrifying genes in tropical natural forest, but only by nitrifying genes in managed forests and by denitrifying genes in paddy field. Soil total N, extractable nitrate, particulate organic C (POC), and hydrolyzable ammonium N showed positive relationship with soil N₂O emission. The easily oxidizable organic C (EOC), POC, and light fraction organic C (LFOC) had positive linear correlation with the abundance of AOA-amoA, AOB-amoA, nirK, and nirS genes. The ratios of dissolved organic C, EOC, POC, and LFOC to total N rather than soil C/N ratio control soil N₂O emissions with a quadratic function relationship, and the local maximum values were 0.16, 0.22, 1.5, and 0.55, respectively. Our results provided a new evidence of the role of soil C and N fractions and their ratios in controlling soil N₂O emissions and nitrifying and denitrifying genes in tropical soils.

Keywords: N cycle pattern; Soil C and N fractions; Soil C/N ratio; Soil N(2)O emission; Tropical region.

MeSH terms

Carbon*
Ecosystem
Nitrogen
Nitrous Oxide / analysis
Soil Microbiology
Soil*

Substances

Soil
Carbon
Nitrogen
Nitrous Oxide