Acta Agriculturae Zhejiangensis ›› 2025, Vol. 37 ›› Issue (10): 2150-2164.DOI: 10.3969/j.issn.1004-1524.20240828

• Environmental Science • Previous Articles     Next Articles

Interactions of soil carbon and nitrogen distribution with nitrogen fixing and denitrifying bacteria community under straw returning

WANG Yunlong(), JIA Shengqiang, CUI Lingyu, LYU Haohao, SHEN Alin, SU Yao()   

  1. Institute of Environment, Resource, Soil and Fertilizer, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
  • Received:2024-09-20 Online:2025-10-25 Published:2025-11-13

Abstract:

Based on a 5-year positioning test, the distribution of organic carbon and nitrogen components in soil from 0 to 100 cm depth after straw returning was studied, as well as the changes of soil biological nitrogen fixation and denitrification potential, abundance, diversity and community composition of main microorganisms involved in nitrogen fixation and denitrification, by taking the soil without straw returning as the control (CK). The results showed that straw returning significantly (p<0.05) increased soil organic carbon (OC) and particulate organic carbon (POC) content in 0-60 cm soil layer by 13.1%-243.8% and 36.4%-143.8%, respectively, and mineral-incorporated organic carbon (MOC) content in>20-60 cm soil layer by 89.4%-272.9% than those of CK, yet it significantly decreased soil dissolved organic carbon (DOC) content in 0-60 cm soil layer by 40.6%-75.9%. Under straw returning, the total nitrogen (TN) content in 0-80 cm soil layer was significantly increased by 14.3%-90.3% than that of CK, but the alkali-hydrolyzable nitrogen (AN) and nitrate nitrogen ($\mathrm{NO}_{3}^{-}-\mathrm{N}$) contents in 0-60 cm soil layer were decreased significantly by 16.9%-64.8% and 12.9%-61.9%, respectively; the ammonium nitrogen ($\mathrm{NH}_{4}^{+}-\mathrm{N}$) content was significantly decreased by 11.6%-24.8% in the 0-40 cm layer, yet it was increased to the 1.4 times of the CK in the>40-60 cm layer. Compared with the CK, the biological nitrogen fixation potential in 0-20 cm soil layer was significantly enhanced by 25.2% with straw returning, but the denitrification potential in 0-40 cm soil layer was weakened by 7.8%-82.0%. The copy number of functional genes of nifH, nirS, nirK and nosZ was significantly increased with straw returning than that of CK, which indicated that the growth of nitrogen fixing and denitrifying bacteria was enhanced. The results of structural equation model analysis showed that the changes of soil DOC content, soil nitrogen fixing and denitrifying bacteria abundance had direct influence on the content and distribution of soil $\mathrm{NO}_{3}^{-}-\mathrm{N}$ and $\mathrm{NH}_{4}^{+}-\mathrm{N}$ after straw returning, and the abundance of nitrogen fixing bacteria had the largest direct effect value on the content and distribution of soil $\mathrm{NO}_{3}^{-}-\mathrm{N}$ and $\mathrm{NH}_{4}^{+}-\mathrm{N}$, which was 71.9% and -60.8%, respectively.

Key words: straw returning, soil organic carbon, soil mineral nitrogen, nitrogen-fixing bacteria, denitrifying bacteria

CLC Number: