[Influence of Biochar Amendment on Soil Denitrifying Microorganisms in Double Rice Cropping System]

Jie-Yun Liu; Hu-Sen Qiu; Cong Wang; Jian-Lin Shen; Jin-Shui Wu

doi:10.13227/j.hjkx.201810182

[Influence of Biochar Amendment on Soil Denitrifying Microorganisms in Double Rice Cropping System]

Huan Jing Ke Xue. 2019 May 8;40(5):2394-2403. doi: 10.13227/j.hjkx.201810182.

[Article in Chinese]

Authors

Jie-Yun Liu^{1

2}, Hu-Sen Qiu^{1

2}, Cong Wang^{2

3}, Jian-Lin Shen², Jin-Shui Wu²

Affiliations

¹ Key Laboratory of Water-Saving Irrigation Engineering, Ministry of Agriculture and Rural Affairs, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China.
² Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
³ Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science and Technology, Guangzhou 510650, China.

PMID: 31087881
DOI: 10.13227/j.hjkx.201810182

Abstract

At present, it is not explicit how biochar regulates the microbial process of denitrification in paddy fields. Therefore, a field experiment was carried out in a double rice cropping system with three wheat straw biochar treatments:no biochar treatment (CK), added 24 t·hm^-2 biochar (LC), and added 48 t·hm^-2 biochar (HC). Real time PCR (qPCR) and terminal-restricted fragment length polymorphism (T-RFLP) technology were adopted to analyze the abundances and microbial community structures of denitrification functional genes (narG, nirK and nosZ) in the fallow season and rice season. Due to its alkalinity, biochar amendment increased soil pH by 0.2-0.8. Biochar amendment also increased soil NH₄⁺-N and NO₃^--N contents by 21.1%-32.5% and 63.0%-176.0% in the fallow season due to the presence of soluble N. Nevertheless, it reduced NH₄⁺-N content by 48.8%-60.1% in the rice season due to the adsorption of biochar. The amendment increased soil MBN content in the fallow season, which may be a result of the large surface of biochar supplying nutrients and a suitable survival environment for the microorganisms. In the fallow season, compared to CK treatment, the increased soil NH₄⁺-N and NO₃^--N with biochar amendment promoted the conversion of NH₄⁺-N to NO₃^--N, and thus increased the abundances of narG and nosZ (P<0.05). The higher soil pH with biochar addition increased the abundances of nosZ and altered the community structures of narG and nosZ in the fallow season. Biochar amendment altered the denitrification process, but it did not change N₂O emissions in the fallow season, which might reduce NO₃^--N leaching losses. In the rice season, biochar amendment increased nosZ abundance (P<0.05). HC increased the nirK gene abundance, which contributed to increased N₂O emission in the rice season (P<0.05). Biochar converted the community structures of nirK and nosZ by decreasing the NH₄⁺-N content in the rice season. The changes of the narG community structure with HC treatment contributed to the increased N₂O emission. In conclusion, biochar amendment can influence the microbes involved in soil denitrification by changing the soil properties, and thus impact the N₂O emissions and NO₃^--N leaching.

Keywords: N2O emission; biochar; denitrification microbe; double rice cropping system; soil properties.

MeSH terms

Charcoal*
Denitrification*
Genes, Bacterial
Hydrogen-Ion Concentration
Nitrous Oxide
Oryza / growth & development*
Soil / chemistry
Soil Microbiology*

Substances

Soil
biochar
Charcoal
Nitrous Oxide